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Ian Mackenzie
07-21-2005, 08:12 AM
This thread is dedicated to discussion, (questions, feedback, opinions) of all aspect of the project involving the project design and description thread.

Ian Mackenzie
08-16-2005, 08:56 AM
This thread is now open for discussion.

Lancer
08-16-2005, 10:44 AM
With respect to the photo above - What a mess! :rotfl:

Common guys, I know you all can come up with a better baffle layout than that!

Apply everything we've gone over on this forum the past five years and build something killer.

I look forward to seeing what you guys come up with.

Zilch
08-16-2005, 10:49 AM
Hi, Ian.

Can you start out with a basic description of the two systems, please, and why one might want to upgrade?

I don't know a 4344 from a hole in the ground.

[OR a 4343 from either, for that matter.... :o: ]

Lancer
08-16-2005, 10:59 AM
Hi, Ian.

Can you start out with a basic description of the two systems, please?

I don't know a 4344 from a hole in the ground.... :o:We've gone over it numerous times... what a waste of my time THAT obviously ended up being... :applaud:

Zilch
08-16-2005, 12:00 PM
We've gone over it numerous times... what a waste of my time THAT obviously ended up being... :applaud:Naw, so much the easier, then: Ian can LINK us there! :bouncy:

[An introductory overview would be helpful, is all....]

Regis
08-16-2005, 12:53 PM
With respect to the photo above - What a mess! :rotfl:

Common guys, I know you all can come up with a better baffle layout than that!

Apply everything we've gone over on this forum the past five years and build something killer.

I look forward to seeing what you guys come up with.

Definitely food for thought. I wonder why the 077's are so stinking close to the lenses. You'd think that there might be some interaction between the two, giving the 110 degree dispersion. I might have spaced it out at least a few inches or better yet, put it on top like the L-300.

Robh3606
08-16-2005, 01:52 PM
Here's my idea of an improved layout. Ports in back, drivers in line and offset on the panel mirror imaged. No equal spacing between a driver and a sidewalls. No protruding edges where the grill would mount. The 077 and Lense were kept side by side. The serpentine lense has the same patern for less depth and is low enough that I don't think it interferes with the 077. I think it's look better too:D.

Rob:)

JBLnsince1959
08-16-2005, 02:12 PM
We've gone over it numerous times... what a waste of my time THAT obviously ended up being... :applaud:

:rotfl:


!
Apply everything we've gone over on this forum the past five years and build something killer.

I look forward to seeing what you guys come up with.

maybe we should look at something like this idea instead... :D

Guido
08-16-2005, 02:49 PM
Ian, I hope you keep the 2121 in place. Ripping out nice cones and replace with 2122 kits is not everyones thing.

Tom Loizeaux
08-16-2005, 02:54 PM
I think we should remember that the 4343 was designed for mixdown studios and, though it could be used vertically, was primarily made to hang horizontally above the board! The baffle layout was made rotatable to allow these orientation options and was probably compromised slightly due to this. The 4344 didn't have these requirements. Also, the 4344 came a bit after the 4343, so any new technical understanding could have influenced the subtle changes (or refinements). Some of these new understandings were seen in driver and crossover improvements.
Though I don't hear any significant defficiencies in my 4343s, I have thought about how I might improve things if I were to build an updated pair.
I think I would basically go for the 4344, but would have to consider other questions...like the idea of using a pair of woofers in each cabinet to improve and tighten the low end. I suspect the 2123H would be a stronger mid driver. Maybe a wood horn, or even going to a 1.5 or 2" throat and a 4" diaphragmed driver... maybe even the TAD 4001...? (I suspect the 2405s would stay though)
Ah, see how it all grows?
Maybe simply rebuilding my crossovers for the mid/high/UHF sections in my 4343s would really be enough. ?

This is why I look forward to the development of this thread!

Tom

Ian Mackenzie
08-16-2005, 04:19 PM
With respect to the photo above - What a mess! :rotfl:

Common guys, I know you all can come up with a better baffle layout than that!

Apply everything we've gone over on this forum the past five years and build something killer.

I look forward to seeing what you guys come up with.

I see you are the one who desires the modifications thread.....

That picture was sent some time ago to me by Rob.....yes he is responsible...Lol

Ian Mackenzie
08-16-2005, 04:32 PM
Hi, Ian.

Can you start out with a basic description of the two systems, please, and why one might want to upgrade?

I don't know a 4344 from a hole in the ground.

[OR a 4343 from either, for that matter.... :o: ]

Okay,

I suppose we are appealing to existing owners, or those who have traded their 4343 and after reading the forthcoming wish they hadn't.

The Library has ample information on the 4343, and the JBL system guide has details of the drivers of the respective systems. We will compare the two systems and then discuss the various upgrade steps.

I have not literally had a 4343 and 4344 side by side, but I can say the updates not all of which have been made public yet in a "condensed engineering format" do impart refinement and improvement over the 4343.

In the development of the project we also discovered that despite popular opinion bi amping will not necessarily provide improved Hi Fidelity.
What we do here will be the icing on the Cake among other special fgoodies that will be rolled out in the project.

A system only works as well as the sum of its parts and we will discuss how a total system can perform beyond your wildest dreams!

Ian

Ian Mackenzie
08-16-2005, 04:40 PM
Definitely food for thought. I wonder why the 077's are so stinking close to the lenses. You'd think that there might be some interaction between the two, giving the 110 degree dispersion. I might have spaced it out at least a few inches or better yet, put it on top like the L-300.

Interesting observation.

While measuring the system I found the lense has a dispersion of around 80 degrees, the published polar pattern illustrates this. Looking at the system with correct orientation there is a clear line of site to the slot opening. I will publish if you like measurements of the slot with/without the lense.

I tend to think the two devices work well together "when" adjusted correctly.
The mirror imagine pairs with the slot on the outside does have a significant impact on the imaging. At the crossover wavelength both should be as close together as possible.

Ian

Ian Mackenzie
08-16-2005, 04:47 PM
Here's my idea of an improved layout. Ports in back, drivers in line and offset on the panel mirror imaged. No equal spacing between a driver and a sidewalls. No protruding edges where the grill would mount. The 077 and Lense were kept side by side. The serpentine lense has the same patern for less depth and is low enough that I don't think it interferes with the 077. I think it's look better too:D.

Rob:)

Rob your being a show off but I like it...I know you can take that as a joke.

Well we will talk about a new upper baffle, all the stuff's got to fit somewhere.

The important thing is the offset and non equidistant path lengths.

We had not considering re building new enclosures but I suppose that would fall within scope if those daring enough saw fit to rebuild their 4343 or clone a 4344.

So this will become a real hands on project where members can apply their skills and share ideas., not a chat session.

Ian

Ian

Ian Mackenzie
08-16-2005, 04:56 PM
Ian, I hope you keep the 2121 in place. Ripping out nice cones and replace with 2122 kits is not everyones thing.

Good point.

While out upgrade steps will be clear, concise and distinct.

he individul can of course decide on the degree of enhancement to his/her 4343 system

Be aware however that it will not be a 4344 (spec) and some juggling of the crossover will be necessary if you mix some of the drivers and not others.

Part 9 of the upgrade will also discuss use of modern drivers!

Ian

Ian Mackenzie
08-16-2005, 04:58 PM
Here is the Project Framework.

We spent a while listing all the possible combinations and then rationalised it into these steps.

While not set in stone, the scope of any project has to be clearing defined from the outset, but in any case I think we have most of the bases covered here.

By the way porschedpm wrote the script, no doubt he will come in soon.

Feel free to comment.

Ian

Ian Mackenzie
08-16-2005, 05:11 PM
With respect to the photo above - What a mess! :rotfl:

Common guys, I know you all can come up with a better baffle layout than that!

Apply everything we've gone over on this forum the past five years and build something killer.

I look forward to seeing what you guys come up with.

Hey that's what was intended on a previous attempt to out do JBL, lets please not have an open ended situation...we all know where that can end up..:rotfl:

Lancer you've just been promoted to Head of Special Projects

- Part 9 Discussion on upgrading to modern drivers

yggdrasil
08-16-2005, 07:01 PM
I really look forward to the development here.


Maybe get some ideas to improving my DIY's.

Robh3606
08-16-2005, 07:18 PM
A couple of photo's to compare the baffle layouts. It looks like the 4343 top baffle and bottom baffle could be redone to change the layout. Just set them up off center so the spacing is not the same edge to edge. Take a look at this pirated photo from another thread. Not to sure about the recess for the 2420?? If there is a plate it could be repositioned. Looks to me like the hardest part would be finding someone to mix the JBL Blue. At least with this method you would not have to rebuild the cabinets for a layout change. Just food for thought.

Rob:)

Ian Mackenzie
08-16-2005, 09:57 PM
Ah ,

Bo's in charge on The JBL Blue Paint Mixing and Jean is The Sand Man.

Ian

Ian Mackenzie
08-16-2005, 10:00 PM
Seriously i don't think it would be that difficult to make a new upper baffle, with accurate dimensions and a router jig it could be done.

The entire baffle would need to be re painted.

Heck, why don't we mass produce new baffles....The Widget...where are you!

Ian

porschedpm
08-17-2005, 12:28 PM
IMHO it should be relatively straightforward constructing a new top baffle and deserves to be added as one of the modifications. Blue paint should not be a problem thanks to Bo's successful quest for the correct mix and his community outreach program for teenage paint store employees. I think one of the bigger challenges, though, would be getting a 4344 vertical foilcal produced. Unless your willing to go nude in this respect.

I'd be inclined to leave the bottom baffle as-is since it's permanently affixed to the cabinet and the risk of damaging the cabinet outweighs the benefit that might be gained. IMHO anyway. One of the parameters Ian and I set forth in our framework for this project was that any modifications could be easily un-done or reversed to bring a modded 4343's back to original spec or at least original appearance, due to the relative rarity and rising values of original condition 43xx monitors. Not that any of us are willing to part with our babies, but being these large format monitors are an integral part of the JBL heritage, I feel it is somewhat our responsibility to promote keeping these close to original. I think we're all looking for that next tweak that will bring us closer to musical nirvana but I also think when you're hot rodding a pair of 30+ yr old speakers you can reach a point of diminishing returns where it may be better to start with clean sheet of paper.

saeman
08-17-2005, 01:09 PM
Hi Ian: If you need someone to make a pair of modified upper 4343 baffles, let me know. I have some left over 1" P.B. from my recent 4351 project. Send me a layout with desired dimensions. Would also need the dimensions of the mid-base box. Regards - Rick

saeman
08-17-2005, 09:13 PM
Hello Ian: Thanx for getting this thread started - I'll be following it closely and will contribute what I can to your effort however I have no experience with the 4344. I do have a few questions.

Does anyone have the factory dimensions for the 4344 cabinet??? The 4343 cabinet is 41 3/8" H x 25" W x 15 1/8" D w/o grille. The 4344 MKII is the same. Can I assume that the 4344 is the same too? Is the mid base box for the 2122 the same volume as that for the 2121? What is the diameter of the two ports and the duct tube length? Those are easy questions, right !!

I started to cut wood for a pair of 4344's some time back but then put the project on hold. I was planning on starting up again and got a bad report on the factory baffle layout from Giskard. I have since layed out a new baffle resembling the one posted by Ian in an earlier thread, with 2235H non-equadistant to the cabinet sides. I'll hopefully build the cabinets this fall.

I'll be able to follow this discussion thread during my cabinet construction and throughout my hunt for components. I will no doubt end up with a better pair of 4344's as a result.

http://audioheritage.org/vbulletin/images/smilies/smile.gif Rick

Ian Mackenzie
08-17-2005, 09:55 PM
Hi Ian: If you need someone to make a pair of modified upper 4343 baffles, let me know. I have some left over 1" P.B. from my recent 4351 project. Send me a layout with desired dimensions. Would also need the dimensions of the mid-base box. Regards - Rick

Thanks,

That will be great!

Ian

Ian Mackenzie
08-17-2005, 09:58 PM
Hello Ian: Thanx for getting this thread started - I'll be following it closely and will contribute what I can to your effort however I have no experience with the 4344. I do have a few questions.

Does anyone have the factory dimensions for the 4344 cabinet??? The 4343 cabinet is 41 3/8" H x 25" W x 15 1/8" D w/o grille. The 4344 MKII is the same. Can I assume that the 4344 is the same too? Is the mid base box for the 2122 the same volume as that for the 2121? What is the diameter of the two ports and the duct tube length? Those are easy questions, right !!

Hi ,

We will need to check that out, let me come back to you, I think the mid enclosure is identical VB

I started to cut wood for a pair of 4344's some time back but then put the project on hold. I was planning on starting up again and got a bad report on the factory baffle layout from Giskard. I have since layed out a new baffle resembling the one posted by Ian in an earlier thread, with 2235H non-equadistant to the cabinet sides. I'll hopefully build the cabinets this fall.

Yes, good idea

I'll be able to follow this discussion thread during my cabinet construction and throughout my hunt for components. I will no doubt end up with a better pair of 4344's as a result.

Absolutely

http://audioheritage.org/vbulletin/images/smilies/smile.gif Rick

Lets just look into this fine detail,

Thanks for your input and enthusiasm

regards

Ian

Ian Mackenzie
08-18-2005, 02:08 AM
We also plan to look at the whole biamping scene.

There are pros and cons for both conventional passive and bi amping.

In fact I intend to subjectively compare the JBL 5235 very shortly to a hi quality discrete class A crossover and conventional passive mode.

Ed will also describe no doubt his intitial impressions of a full passive crossover after using an Ashly active crossover in his system.

Ian

Lancer
08-18-2005, 06:42 AM
In fact I intend to subjectively compare the JBL 5235 very shortly to a hi quality discrete class A crossover and conventional passive mode.Ouch!
We've discussed the 5234A and 5235 before along with how to improve them. One can easily hear why JBL used passive high pass filters in the BX63 and DX-1 once they hear a 5234A or 5235. ;)

Akira
08-18-2005, 09:46 AM
this is a good thread because, having no experience with this monitor, (except lusting after a pair) i have imagined how i would line up various combinations of drivers and positioning. i would go totally in line, perfectly symetrical if space allows. i always imagined a 2441 in place of the 1". the great thing about JBL, that i'm sure you can all relate to, is that each series of driver has an identifiable aural signature with a common heritage...they share similar acoustic properties that can be molded into a musical instrument...a work of art really. the wife is having a hard time with the 'art' part. i look forward to following this thread.

p.s. for the sake of new members who are starting to discover this site, it would help if those of you who have been around for a while not spoil it for us with comments like, "we've discussed this so many times before." it's dissappointing when a thread is prematurely ended...it's all new to me.

norealtalent
08-18-2005, 01:44 PM
[QUOTE=porschedpm] I think one of the bigger challenges, though, would be getting a 4344 vertical foilcal produced. Unless your willing to go nude in this respect.

I can get foil cals done in .022 stock without serial #'s for about $50 a pair when ordering 10. I had some done for 4343's. Of course an original is required to make a copy.
Edit: Nudity should be reserved strictly for the use of "buttcheeks." Whether they be small, medium or large is by personal preference. I prefer them all... nude, of course.:bouncy:

Ian Mackenzie
08-18-2005, 02:13 PM
Ouch!
We've discussed the 5234A and 5235 before along with how to improve them. One can easily hear why JBL used passive high pass filters in the BX63 and DX-1 once they hear a 5234A or 5235. ;)

Yep,

Well as stated in post 13 by adopting a system this approach ensures the system bring the some of all components does infact add, not subtract to total performance improvement.

I tend to think this in many ways is what implementing and getting the best out (not designing per say) a hi performance speaker is about.

It is easy to modify and go the minimalist route but not end up with the right specification.

But if engineered correctly one can extract the right level of performance.

I bought yesterday some 0.018, 0.12. , 0.33 , .033 polystyrene capacitors to build an 18 db unity gain crossover. These are very large values of this kind of capacitor. I also intend to try charge-coupling the small signal electronics.

These parts will also be used in the 5235 cards to assess improvements to the 5235 crossover. I am sure there are members out there who will desire a better way of bi amping

I want avoid using the term tweak in the project. It conjures up the impression or interpretation of modification or change in the specifications and is too general. Tweaking is often a change to ones liking (not to be confused with taste but rather wanking) rather than a technically desireable improvement.

Of course one can individualise what steps will be taken to update to 4343 per the project framework.

Ian

Below is a distortion graph of a new prototype active crossover. The 4344 crossver will be less is more (better again) and built for the purpose.

Ian Mackenzie
08-18-2005, 02:23 PM
[QUOTE=porschedpm] I think one of the bigger challenges, though, would be getting a 4344 vertical foilcal produced. Unless your willing to go nude in this respect.

I can get foil cals done in .022 stock without serial #'s for about $50 a pair when ordering 10. I had some done for 4343's. Of course an original is required to make a copy.
Edit: Nudity should be reserved strictly for the use of "buttcheeks." Whether they be small, medium or large is by personal preference. I prefer them all... nude, of course.:bouncy:

Very good, we will have to keep you in mind.

Ian

Ian Mackenzie
08-18-2005, 02:31 PM
I think we should remember that the 4343 was designed for mixdown studios and, though it could be used vertically, was primarily made to hang horizontally above the board! The baffle layout was made rotatable to allow these orientation options and was probably compromised slightly due to this. The 4344 didn't have these requirements. Also, the 4344 came a bit after the 4343, so any new technical understanding could have influenced the subtle changes (or refinements). Some of these new understandings were seen in driver and crossover improvements.
Though I don't hear any significant defficiencies in my 4343s, I have thought about how I might improve things if I were to build an updated pair.
I think I would basically go for the 4344, but would have to consider other questions...like the idea of using a pair of woofers in each cabinet to improve and tighten the low end. I suspect the 2123H would be a stronger mid driver. Maybe a wood horn, or even going to a 1.5 or 2" throat and a 4" diaphragmed driver... maybe even the TAD 4001...? (I suspect the 2405s would stay though)
Ah, see how it all grows?
Maybe simply rebuilding my crossovers for the mid/high/UHF sections in my 4343s would really be enough. ?

This is why I look forward to the development of this thread!

Tom

Welcome Tom,

Don may be able to confirm this but the 4344 was sold largely in Japan for the domestic audiophiles over there. A sub like the 1500 may be a worth option..Lancer may have input on the as things pan out.

About the steps to improvement, I don't think we need to take extreme measures. Of course a rebuild of the enclosure would be an option if you prefer to keep your original 4343 as is.


Ian

Ian Mackenzie
08-18-2005, 04:26 PM
Documentation with references to both the 4343 and 4344 is an important part of the project.

If someone can post some links (ie the library and key threads & posts, jblpro.com, 4343 reviews) we will have a means of accessing important data.

I know myself I have previously posted some drawings and other also, so we need to locate and review these posts.

Thsi information once verified can be posted into the design thread. will start on this over the weekend. I suggest we all have a look around and come back with some links.




Ian

saeman
08-19-2005, 03:42 PM
Hello Ian: Please take a look at the enclosure cutaway that I am planning for my hybrid 4344's. It's to approximate scale but just a sketch. My plan is to provide a recessed area at the upper rear of the cabinet to house all of the electronics related to the crossovers. All components, with the exception of the baffle mounted pots, will be outside of the pressure hull. I may leave this area open or possible provide a removable cover. To make up for the loss of internal volume I increased the cabinet depth 2". The resulting internal volume is near identical to the stock 4344. From the front it's height and width will look identical to the factory 4344. My question is "To all of the custom x-over guys out there" - Is there enough room in this area to house the necessary x-over components - coils, caps, gadgets, dugans, etc. ??? Assuming replies to the positive, I want to push on cutting wood and making the cabinets. Thanx in advance - Rick

http://audioheritage.org/vbulletin/images/smilies/bouncy.gif

Regis
08-19-2005, 03:50 PM
Very interesting Rick and mounting the crossover outside would make it easier to do mods on the X-overs, plus you'd have unlimited room out the back. I'm curious as to how you'd run the wiring from the external to the internal and whether or not it would have to be sealed or would you use connectors (like we do in areospace) through the 'bulkhead'? Secondly, if externally mounted, would you go with some kind of wire cage to protect the passives from any thing falling into them? Hoping a little forward thinking before cutting would help (even with my limited experience).

saeman
08-19-2005, 04:02 PM
I'm curious as to how you'd run the wiring from the external to the internal and whether or not it would have to be sealed or would you use connectors (like we do in areospace) through the 'bulkhead'? Secondly, if externally mounted, would you go with some kind of wire cage to protect the passives from any thing falling into them?


Thanx for the thoughts. For the wiring to the three pots I would use a single Beldon type multi conductor cable, like JBL uses, and a single penetration into the cabinet using a compression type connector. For the wiring to the four components themselves I thought an array of threaded copper studs thru the back might be a good thing. Arrange them 2 wide x 4 high, a pair for each component. They could easily be sealed at their point of penetration and nuts/ring connectors would ensure a good low resistance connection. Just my thoughts at this time. Keep in mind that I don't know diddly about custom x-overs.

Ian Mackenzie
08-19-2005, 04:26 PM
Interesting idea Rick,

Your design criteria has many of the ingrediance that "we" discussed when evolving the reference system for Ed.

When we thought it through it became clear that a new 3145 network would best be external to the crossover The reason is where would the network go in inside the enclosure and we wanted to leave the original crossover/wiring/L pad entact per Ed's comments above? That is the changes should be reversable(the Pads would have to be replaced for the 3145 network)

Secondly, how to organise the wiring to ensure a neat air tight seal and avoid the phase errors that can easily occurr with a 4 way system. What I came up with was a nice 8 pole speakon sock and plug . This plug accepts up to 13 gauge wire.

The solution was an external crossover about the size of a PL mini tower with the L pads on the front of it.

I like your idea but it will require a re build of the enclosure. There would appear enough surface area.

Are you making your from baffle removeable or the rear panel?

Ian

saeman
08-19-2005, 04:35 PM
Are you making your from baffle removeable or the rear panel?

Ian: Neither the baffle nor the rear panel are removable. They are glued solid into the sides, top and bottom. Why do you ask ?

Ian Mackenzie
08-19-2005, 04:38 PM
Rick,

I will post these drawing at least temporarily for you to down load.

Please check the dimensions for accuracy before cutting.

Ian

Ian Mackenzie
08-19-2005, 04:46 PM
The other drawings are here.

Ian

saeman
08-19-2005, 04:58 PM
Ian: Thanx for the drawings. I think I downloaded most of them from one of your earlier threads, however I just downloaded them again. On these details I do not see the depth of the mid-base box or the diameter of the two baffle ports. Is this info listed elsewhere?? Thanx - Rick

Ian Mackenzie
08-19-2005, 06:19 PM
Here it is.

I am not sure about the port length....I amsure its around in one of the many threads earlier on

Ian

Ian Mackenzie
08-19-2005, 07:19 PM
Ian: Neither the baffle nor the rear panel are removable. They are glued solid into the sides, top and bottom. Why do you ask ?

Well some how you will need access to the compression driver and slot otherwise it will be almost impossible to remove the driver if it requires servicing.
The same applies to the 2405.

I don't know about the 4344, but the 4343 had a removeable front baffle and the 4345 has a removeable rear panel for this reason.

Ian

saeman
08-19-2005, 08:48 PM
Well some how you will need access to the compression driver and slot otherwise it will be almost impossible to remove the driver if it requires servicing. The same applies to the 2405.

Ian: I've never been a fan of a screwed down baffle. The two pairs of 4343's I've owned had their upper baffle sections removed some unknown number of times. The screw holes were deeply recessed into the wood and after a while the screw threads get stripped out. Removable rear panels remind me of most of Altec's cabinets, not made near as well as JBL's. The enclosure integrity is always at stake. Sealing tape is required and it just seems like a hassle.

Consider this option - My baffle is very similar to the one you posted in this and other threads on the 4344. Between the compression driver and the woofer cutout there sits the big obstacle of the mid-base box. You can however take the driver/horn in hand and reach around the mid-base box. If one lacks the arm strength to lift/hold it into place until the screws are installed there's another little trick I learned from other projects. With one hand put the horn in position and using the other hand reach thru the cutout and stand it up under the hole. Take two pieces if 1/4-20 threaded rod with an "L" bent on one end and insert them thru two of the 4 mounting holes in the baffle and screw them into the horn. Then use the rods to pull the assembly up into place. Put the two opposite screws in, remove the rods and install the other two screws. The 2405 presents no problems with your baffle layout.

Is all of this anal - maybe to some. Building a box with all panels glued and screwed solid and doing business thru the baffle cutouts is always a better choice. Looking at everything JBL made I'm sure that this method was their first choice. If you don't have strong kids with long arms to help you can always bend up a couple pieces of threaded rod and do it by yourself. Coz the kids aren't always home I have rods too.

Take a close look at my 4351 baffle layout and see if you can figure out how I can get the 2440 and 2405 in and out of the cabinet, based on where they are located relative to the mid-base box and the duct tubes.

Not trying to be a smart ass but if there's anyway you can get around building an enclosure with removable panels - you should do it. My 4351's were a challenge in this arena. Rick

Ian Mackenzie
08-19-2005, 10:48 PM
I suppose that would work.

In the drawings I posted there is a rear panel bracing.

I used this in my own 4345 clone and there are no issues with integrity of the enclosure. I use furniture grade flat head bolts with captive screw-in inserts in the hardwood frame to pull the removeabe baffle hard down on the medium density rubber gasket.

The removable baffle is about 12 inches high x the width of the enclosure. In fact I would say with this particular arrangement where there are two vertical 1x 3 inch braces and a 2 x 3 inch cross brace and also 2 front to rear braces adjoining the Dog Box and the rear panel make it more inert than a single large baffle......but whatever......

Ian

saeman
08-20-2005, 09:26 AM
Hello Ian: I finished looking over your drawings and have extracted the info I need. Will try to start cutting some wood here soon. Although I'm not fond of having the rear panel removable, I do like the thought of a removable panel section and the framing necessary to provide it does beef up the rear panel. My 4341's have an upper removable panel to allow access to the mid and hi drivers. It is tastefully done and the cabinet rear is still good and solid. I'll chug along with the project and see where I end up. The cabinets are the easy part. Still need to locate some of the components (the 2122's should be easy to find, growing on trees I hear - ah, um, blah, ???, etc.) and will also try to work with someone more knowledgable than I am to get the x-overs built. I suspect this will be an on going and long term effort. I appreciate your comments and will keep you posted as I progress. Thanx - Rick

Ian Mackenzie
08-20-2005, 10:10 AM
Rick,

At this early stage we are merely gathering opinions, data and resources, pop in and say hello as you please.

As each stage or step in the frame work is completed in the bhow to guide permanent data will be posted to the design thread.

Obviously members will pick up the project as you have done at a particular point and we wll do our best to accommodate you needs. We plan to progress through the steps as previously advised as this is the most logical approach.

Ian

Ian Mackenzie
08-20-2005, 08:21 PM
One of the things I am mindful of is the question "what can I expect from these changes" particularly in reference to steps 5, 6 and 7. And not everyone one will be keen to starting making updates without some knowledge of the gains or improvements.

This has not been an easy issue to provide specific answers on so we been doing some very interesting tests and comparisons.

First off, we need to look at the 4343 in terms of its have's and have not's and in order to see what is going on in the system this means operating it at its basic level. This means full passive mode.

So Ed and have been doing some listening comparisons to arrive at some conclusions and applying the results to the technical side.

Step 4 has not been fully explored however working on the premise that good terminations are vital any unnecessary switches should be removed from the signal path.

To test this I placed a heavy duty jumper lead with crocodile clips in series with the positive input to the crossover network and did some blind test comparisons.

The cable was pure OFC and terminated to a Cardas hi quality binding post.
Inserting the jumper lead in series with the crossover and the amps caused a loss of low level information and the sound stage collapsed and sounded flat and planar.

So, while cables are often the flavour of the month in audiophile chat rooms please be aware that it's the terminations that are the final arbitrator of conductivity. Hence, a switch or other brass contact, oxidised or otherwise will downgrade the purity of the signal. Think of the amp as your car battery and the speaker as the starter motor.....its a good analogy.

Good terminations...we will discuss this in more detail in step 4.

Step 5. Upgrading the stock crossovers. This is the most popular issue and also the most expensive and controversial update for anyone contemplating a speaker restoration or a new design.

Again, we have organised some comparisons and have come to some conclusions. Some of these comparisons were conducted with the 4343 system and others simulated using the reference system the 4345.

Specifically in the 4343 the 3143 crossover has the midrange, horn and slot signal routed via a 52 uf capacitor in the midrange bandpass filter.

This was done according to JBL to improve the protection to the compression driver and slot from amplifier turn on/off transients. In the early days this was a problem but with modern amplifiers it is far less of an issue.

In a recent comparison with the reference system I was able to determine that the arrangement of this capacitor does cause a loss on information to the compression driver and slot. Specifically a loss of ambience and very fine details....much like a more polite but otherwise muted sound that lacked snap and dynamics. The series capacitor was a Solen polypropolyne metalised film foil bypassed with a 0.1 Solen film and foil capacitor (not charge coupled). The amplifier used was a Passlabs Aleph design.

By removing the capacitor entirely and putting the system in bi amp mode using a very special, and hi quality active crossover we also observed marked improvements in midrange clarity, transparency and improved purity. This was very noticeable on vocal harmonies where individual voices could more easily be identified. The active crossover used in this comparison is a discrete class A unit with a Passlabs Aleph amplifier on the highs and a PSS 600 amplifier on the lows.

We also observed that the 4343 in full passive mode can perform better than in active mode and the determining factor here is the performance of the active crossover and the amplifiers. Again a loss of information lead to less realistic results in biamp mode while the bass was more detailed ahd more authority in bi amp mode. The crossover used in this comparison was the Ashly analogue unit using a Passlabs X 250 amplifier on the lows and Mac amplifier on the highs. A Passlabs X 250 amplifer used in full passive mode.

So we can see that by reviewing the crossover network, the manner in which it is arranged and the use of a hi quality active crossover will yield a net improvement in musical performance.

Details of various upgrades will be discussed in step 5.

Step 6 Biamping Pros and Cons

Refer to step 5. The pros are improved bass clarity and authority. The cons are loss of transparency, imaging and information. The extent of the later will depend on the active crossover in use. Analogue active crossovers a deemed better and more affordable for home use than pro audio digital active crossovers. However budget prices will only buy budget performance in both cases.

Crossovers available on the Market.

Well there are dozens from entry level units like the Ashly, the JBL 5235, the Bryston and the Passlabs. The last 2 are premium grade but aren't cheap. Please note 4343-4343 does however require a specific crossover characteristic in order that the system works correctly.

I may be enticed to assist with providing a customised crossover with appropriate performance to interested parties. Pm me for details.

Step 1, 2 and 6

Surprisingly drivers to deteriorate with age,particularly the compression driver diaphram. Have it check by an authorised JBL agent/reconer.

There in an improve driver/diaphragm used in the 4344...the 2425J and there is rare aluminium versions of the diaphram seen on Ebay.

While is had previously built a cloned 4343 its on on sight for direct comparison with updated driver. The 2425J is a superior a driver and the aluminium variant of the diaphragm sort after.

Many have trouble taming the horn in the 4343, I think this is one of the biggest issues with the 4343. The solution is a mix of driver, crossover upgrade and careful setup.

I have used both the 2231A and the 2231H and 2235H. There are differences in power handling and subtle differences in performance. The 2121 and the 2122H are different beasts. I have not A/B'd them so I can't comment. The 2122H does however require a different passive crossover.

We will discuss this in more detail later and perhaps other members can post there experiences with driver updates.

Summary

As mentioned in an earlier post it is important to view the loudspeaker as a system. That is the sum of all the parts of the system come together to create the desired level of performance.

In order to obtain the maximum potential from the loudspeaker we must therefore look critically at each part of the system and decide what updates are required and "how" to implement those updates.

From our investigations we have identified the 4343 system in its raw state is far from capable of producing the maximum potential of its performance. Care needs to be taken when introducing ancilary equipment like active crossovers or graphic equalisers, as they could well be hindering rather than providing a net gain to attaining the maximum potential performance from the system.

The purpose of this post was to give some degree of indication on the net effect of these updates.

Ian

Tom Loizeaux
08-23-2005, 04:48 PM
p.s. for the sake of new members who are starting to discover this site, it would help if those of you who have been around for a while not spoil it for us with comments like, "we've discussed this so many times before." it's dissappointing when a thread is prematurely ended...it's all new to me.[/QUOTE]

I agree that, though some things seem obvious or have been discussed to where we think it's "common knowledge", we should try to make these "4343 to 4344 Upgrades" postings as thorough as possible.
I, for one, plan on printing out the succinct pages for a file on this subject...for studying later!

Thanks again, Ian and others, for getting this thread going.

Tom

Ian Mackenzie
08-23-2005, 05:01 PM
Tom,

I think that has been rectified.

Ian

saeman
08-26-2005, 07:53 PM
Ian: Took a crack at cutting one of my 4344 baffles - 1" P.B. with the mid-base box out of 3/4" P.B. The component layout is similar to the design you posted, with drivers in vertical alignment and non-equadistant to any of the cabinet walls. I moved the ducts down a bit to allow access to the upper internal area for installation of the mid range driver thru the woofer cutout. The other one will be a mirror image of this one. Before I cut the next one - your comments please. Duct tube length is still evading me. Combed thru many many posts and am finding nuttin.

http://audioheritage.org/vbulletin/images/smilies/smile.gif

Ian Mackenzie
08-26-2005, 08:19 PM
Looks good Rick

The main thing is to make sure everything fill fit together.

ie the drivers, dog box etc will clear any internal aspects on the main enclosure.

Remember there is a brace for the horn driver.

If you plan to make te front baffle permanent why not use the side wall as the enclosure wall for the Dog box!

Ian

saeman
08-26-2005, 08:41 PM
Remember there is a brace for the horn driver.

BRACE FOR THE HORN DRIVER ????? What brace ?? I was not aware of this. Is it something like that used to support the weight of the 2440 in the 4350 ?? Or is it a cradle that holds the end of the motor like that used in the 4331/4333 ???


If you plan to make te front baffle permanent why not use the side wall as the enclosure wall for the Dog box!
Ian

I had planned to use two 1 1/2" x 2 1/2" braces, front to back on each side panel. Moving the dog box full right, with it's own side panel, will take the place of the two side braces on one side of each cabinet. After assembling the cabinet I'll go in thru the mid-base cutout and screw the dog box wall to the cabinet side (glue between the two).

Thanks for chiming in. Rick

Ian Mackenzie
08-26-2005, 08:56 PM
BRACE FOR THE HORN DRIVER ????? What brace ?? I was not aware of this. Or is it a cradle that holds the end of the motor like that used in the 4331/4333 ???

YES



I had planned to use two 1 1/2" x 2 1/2" braces, front to back on each side panel. Moving the dog box full right, with it's own side panel, will take the place of the two side braces on one side of each cabinet. After assembling the cabinet I'll go in thru the mid-base cutout and screw the dog box wall to the cabinet side (glue between the two).

Thanks for chiming in. Rick

Okay

Ian

saeman
08-26-2005, 09:10 PM
Ian: Tell me about this brace that supports the mid driver. Does it attach to the driver? Is it a cradle to support weight?? I didn't see anything in your drawings. There isn't anything in the 4343's. Was this new to the 4344?

Tom Loizeaux
08-26-2005, 09:37 PM
... Duct tube length is still evading me. Combed thru many many posts and am finding nuttin.
http://audioheritage.org/vbulletin/images/smilies/smile.gif

The duct length on the stock 4343s is 8 1/4" for each tube.

I think your work is great! You've come up with a subtle, but definite improvement.
If it were me, though, I think I'd place the 2405 slot directly above the 2420... making a slightly taller cabinet. I like the high end to be up to head level when ever possible.
Great work!

Tom

saeman
08-26-2005, 10:14 PM
The duct length on the stock 4343s is 8 1/4" for each tube.

I think your work is great! You've come up with a subtle, but definite improvement.
If it were me, though, I think I'd place the 2405 slot directly above the 2420... making a slightly taller cabinet. I like the high end to be up to head level when ever possible.
Great work!

Tom

Hi Tom: Thanx much for your comments. I agree with you on having the 2405 on top and I struggled with the idea and decided not to do it. I have in the past, built tall towers for the express purpose of getting the components up off the floor and projecting into the listening area better. Since I'm calling these 4344's I'm gunna make them look exactly like those built by our buddy James. One exception - since they're never going to be hung or layed on their side, I'm going to mount them on a base and I'm thinking of angling the base so that they tilt back 3-5 degrees. For my intended listening area this should help to better disperse the highs. We'll see. Regards - Rick

Ian Mackenzie
08-26-2005, 11:47 PM
With the slot on top the dilema is its the narrow vertical polar pattern.

With the slots on the side/outer the action of the crossover polar geomtry is to angle the 8K frequencies and above towards the listening in the middle.

Ian

Ian Mackenzie
08-27-2005, 12:06 AM
More experiments.....

Been listening to the stock JBL 5325 crossover today with 4345 cards that just arrived from Santa Rosa CA....thankyou SpeakerDave.:applaud:

Well its been very interesting.

The good news is it's very clean sounding.

The bad news is the 5235 crossover makes every recording sound the same .......:blink: .

A . By this I am referring to the presentation......there is a very strong sense of presence in the midrange, lots of drive.

If your JBLs sound in your face then this is why.....and ultimately fatiguing.:blink:

I think this is another long held characterisation and a false one at that of JBL's in particular the 4343 that is going to be sorted out in this project.

Basically the speakers are a hi end system and it these sort of issues that ear mark hifi from hi end.

B. I compared it to my own crossover and it by comparison sounds perhaps reserved, not in your face. Once I played different stuff the skill of the recording engineer becomes obvious. The music has soul and natural energy.

Removing the active crossover gives the same result as B with some loss of bass detail.

I will attempt the null dc offsets the discrete opamps and bypass the coupling capacitors (B) and see what happens.

I decided to completely bypass (short out) the audio coupling capacitors in a key area just to see what might happen.......

Well let me say its going to stay that way......

I will refer to this as the Earl revision to the design.

The very fine detail and nuance at frequency extremes has opened up while the mids now a sheer clarity that is difficult to describe. Individual tracks appear to take longer to play while at the same time I now feel compelled to focus on the characteristics of specific instruments.

This perhaps is a sign of one being at ease and accepting the sound as correct.... I think so.

I now propose to charge couple the polystyrene capacitors in the actual crossover filters. This will be referred to as the Giskard revision to the design.

What amazes me is that one easily can pick and hear all these refinements up on a 20+ year old loudspeaker design.

Ian

Tom Loizeaux
08-27-2005, 08:13 AM
...With the slots on the side/outer the action of the crossover polar geomtry is to angle the 8K frequencies and above towards the listening in the middle.

Ian

I've always set up my 4333s & 4343s with the slots on the inside, feeling that having a direct line-of-sight to the 2405 slot is better then having some of the slant plate fins in the way. Am I mistaken?

Tom

Ian Mackenzie
08-27-2005, 08:33 AM
Each to his own Tom and I would normally agree "if" all the drivers are in the same vertical plane...but not in this instance.

This my graphic below...I'm not much of an artist but there we are.

In the region of the crossover point both the horn and slot overlap and there will be a polar tilt in the direction of the arrow...its that simple. hence I prefer the slot on the outside....I recall the 4344 manual says a much somewhere.

If you put the slot above the horn some of the highs will be pointed at your ceiling!

Ian

Ian Mackenzie
08-28-2005, 06:34 PM
More experiments.....

Been listening to the stock JBL 5325 crossover today with 4345 cards that just arrived from Santa Rosa CA....thankyou SpeakerDave.:applaud:

Well its been very interesting.

The good news is it's very clean sounding.

The bad news is the 5235 crossover makes every recording sound the same .......:blink: .

A . By this I am referring to the presentation......there is a very strong sense of presence in the midrange, lots of drive.

If your JBLs sound in your face then this is why.....and ultimately fatiguing.:blink:

I think this is another long held characterisation and a false one at that of JBL's in particular the 4343 that is going to be sorted out in this project.

Basically the speakers are a hi end system and it these sort of issues that ear mark hifi from hi end.

B. I compared it to my own crossover and it by comparison sounds perhaps reserved, not in your face. Once I played different stuff the skill of the recording engineer becomes obvious. The music has soul and natural energy.

Removing the active crossover gives the same result as B with some loss of bass detail.

I will attempt the null dc offsets the discrete opamps and bypass the coupling capacitors (B) and see what happens.

I decided to completely bypass (short out) the audio coupling capacitors in a key area just to see what might happen.......

Well let me say its going to stay that way......

I will refer to this as the Earl revision to the design.

The very fine detail and nuance at frequency extremes has opened up while the mids now a sheer clarity that is difficult to describe. Individual tracks appear to take longer to play while at the same time I now feel compelled to focus on the characteristics of specific instruments.

This perhaps is a sign of one being at ease and accepting the sound as correct.... I think so.

I now propose to charge couple the polystyrene capacitors in the actual crossover filters. This will be referred to as the Giskard revision to the design.

What amazes me is that one easily can pick and hear all these refinements up on a 20+ year old loudspeaker design.

Ian

After evaluating the 5235 Crossover and the earlier comparisons Ed did b/n full passive an the Ashly active crossovers I am convinced active crossovers can be the route of all Evil in attaining hi end sound quality.

The driver upgraded 4344 is quite capable of hi end sound reproduction if
only given a chance.

Sure, nice passive crossover parts refine and improve transparency but the effect of the Pro PA active crossover cannot be undone..ever....:blink:

My tests and modifications which I am yet to finalise on my own class A
active crossover confirm the level of subjective sound quality the 4344 can
provide.

Done right, an active crossover can provided pin sharp bass transients and
mid range clarity unattainable with a full passive crossover.

Done wrong and its all a pointless exercise...unless of course you prefer listening to Mid Fi.

Yes this does sound like a rant and maybe some of you already appreciate the above. I just find it very annoying that JBL never put out a better unit for these vintage monitors......its not as though they were'nt selling in Japan.:banghead:

Ian

Lancer
08-28-2005, 07:38 PM
I just find it very annoying that JBL never put out a better unit for these vintage monitors...Yep...

porschedpm
08-28-2005, 08:33 PM
Ian, if I hear you correctly Pro PA components may not be the best choice for someone looking to wring the last bit of musical enjoyment out of their Hi End home system. Is this because:

1) For the most part, the intended use of Pro PA quality components is different than the indended use of Hi End components. Pro PA needs to reproduce music usually at sound levels that would be unacceptably loud for most home environments. At these louder sound levels, the sound engineer is would be concerned more with accuracy, lack of distortion, room acoustics, feedback, etc. than looking for the nuances and delicacies within the music. I think both the sound engineer and the audiophile both would be looking to minimize hum but a noise level that what would be acceptable to the sound engineer would not be for the audiophile.
2) Certain of the goals of Pro PA components are achieved at the expense of the some of the goals of Hi End components.

Did JBL ever produce a Hi-End audiophile type active crossover, say for the Synthesis or K2 series.

Ian Mackenzie
08-28-2005, 09:44 PM
Ian, if I hear you correctly Pro PA components may not be the best choice for someone looking to wring the last bit of musical enjoyment out of their Hi End home system. Is this because:

1) For the most part, the intended use of Pro PA quality components is different than the indended use of Hi End components. Pro PA needs to reproduce music usually at sound levels that would be unacceptably loud for most home environments. At these louder sound levels, the sound engineer is would be concerned more with accuracy, lack of distortion, room acoustics, feedback, etc. than looking for the nuances and delicacies within the music. I think both the sound engineer and the audiophile both would be looking to minimize hum but a noise level that what would be acceptable to the sound engineer would not be for the audiophile.
2) Certain of the goals of Pro PA components are achieved at the expense of the some of the goals of Hi End components.

Did JBL ever produce a Hi-End audiophile type active crossover, say for the Synthesis or K2 series.





1.Not really, the JBL BX 63 was aimed at the home user and was designed as such, so was the now defunked DX1. What's in the 5235 is ancient but well executed, the chips used in it were the order of the day however have been since outlawed from consumer CD players and pre amps because they sound bad compared to other more recently developed options.

2. I don't know........

If the truth be known I think they would be somewhat frustrated but what's done is done and water under the bridge.

Lancer
08-29-2005, 05:45 AM
Did JBL ever produce a Hi-End audiophile type active crossover, say for the Synthesis or K2 series. The DX-1 is considered to be a very good example of how to do a proper bi-amp network. JBL still uses the DX-1 for R&D. There is plenty of information about it here on the forum. The JBL M9500 and the JBL XPL200A with their specific DX-1 crossover cards are very good examples of properly bi-amped systems.

saeman
08-29-2005, 03:31 PM
Ian, Lancer and other Electronic Gurus contributing to this thread - I've read a lot on the forum about custom x-overs but have seen NONE in person. JBL put everything in a neat metal box and it just screwed into the cabinet interior. All of you guys that are building custom x-overs leave me wondering what the end product looks like, how big it is and how/where they are mounted and how much room one should allow in the cabinet to mount a custom x-over. On the forum I have seen all kinds of pics of different x-overs - hugh toroidal coils, jumbo caps, circuit boards with IC's on them, etc. Does anyone have a picture that shows the end product, of a custom built x-over project, for a 4343, 4344,4350 type system - Thanx in advance Rick http://audioheritage.org/vbulletin/images/smilies/banghead.gif

Ian Mackenzie
08-29-2005, 04:37 PM
Rick,

The general idea is to buy the parts build the crossover first.

However if space is a premuim the passive crossover can be build on layers.

You can assume an electronic crossover will occupy 1-2 19 inch rack unit.

Ian

Ian Mackenzie
08-29-2005, 04:51 PM
If the WAF is an issue hide everything in wifey's pantry..that's what Bo does.

Ian

saeman
08-29-2005, 04:59 PM
Rick,

The general idea is to buy the parts build the crossover first.

Then I was looking at the project ass backwards. I figured the x-overs were the last thing to worry about.


However if space is a premuim the passive crossover can be build on layers.

I have seen, I assume x-overs, with stacked boards so this makes sense.


You can assume an electronic crossover will occupy 1-2 19 inch rack unit.

1-2 rack units is quantatative so now I have a picture of necessary volume.

This whole idea is new to me - can't blame me for wondering. If this was a private forum all the "newbies on certain subjects" would not be cluttering up your thread with stupid questions (stupid to some I suspect).

As always, thanx for your answers.

saeman
08-29-2005, 05:06 PM
Ian:

Earlier in this thread there is a pic of a mounting board that is the entire height and width of a 4343 cabinet. On it are mounted tons of coils and other caps and gadgets. Obviously it's the cross over for this monitor. So.....As a new guy on this subject - on the outside looking in - is this a typical custom x-over in size and complexity - or - is this something exotic and not what you would call a run of the mill custom x-over. This baby obviously takes up some space.

Regards - Rick http://audioheritage.org/vbulletin/images/smilies/wink.gif

Ian Mackenzie
08-29-2005, 06:00 PM
Rick,

That was an exotic approach to contruction and not absolutely necessary.

You need to decide on the drivers, then the crossover and so on.

The active crossover is an anciliary device best placed near your pre amplifier and power amps.



Ian

Zilch
08-29-2005, 06:06 PM
Hi, Rick.

Assuming Ian doesn't mind me jumpin' in, here's the deal as I see it:

1) Generally speaking, an improved passive crossover can be constructed in the same space that JBL's original occupied. That would include adding bypass capacitors and aircore inductors where appropriate, as JBL did not pay much attention to space conservation in layout of early designs.

2) Further upgrading to a biased (charged-coupled) version of a standard passive crossover requires twice as many capacitors, and those capacitors are also larger than the originals. Typically, this can be accomplished in less than twice the space of the original. Stacking components and boards can reduce the footprint, but it requires knowledge and experience to get it right.

3) There are tradeoffs involved in passive crossover design and component selection. We have all seen the result of a "no compromises" approach in B&KMan's project. I believe anyone with experience building passive crossovers would characterize the effort as interesting, intriguing, even, but patently "excessive." We have yet to hear even from Jean himself whether the expense was warranted.

4) The crossovers you see here with transistors and IC's on them are "active" crossovers, a different approach in which the filtering is accomplished before the amplifiers rather than after. Being interposed between the source and amplifier, they're typically enclosed and mounted in an equipment rack rather than at or in the speaker cabinet like the passive type, which is connected between the amplifier and the individual drivers.

5) Either approach can be employed to accomplish the task, and sometimes it's a combination of both. Which is better is, well, ummm, "debatable" in nearly every instance.... :p

saeman
08-29-2005, 07:08 PM
Rick,

That was an exotic approach to contruction and not absolutely necessary.

You need to decide on the drivers, then the crossover and so on.

The active crossover is an anciliary device best placed near your pre amplifier and power amps.



Ian

Am glad to hear that the massive array in the pic was on the exotic side of the arena. As a beginner that approach is somewhere in the future for me I would guess.

Driver compliment for my 4344's will hopefully be 2235H's (have two) 2122H's (am researching cone kit availability now), 2425 or 2420/275ND mids (have the horns and lenses) and 2405 (have two). That leaves the x-overs !!! Giskard offered one of his charge coupled systems some time ago and that approach looks to be the best. Will have to leave the physical configuration to him. I'm sure that there will be enough room to accomodate them. Passive/internal with this system is my intent. I have used the JBL 5234's, SAE 4000 and others with my 4350's and have some experience with the active approach (not as extensive as many of you guys out there) but a start non the less.

Thanx for taking the time to reply. Rick

Lancer
08-29-2005, 07:09 PM
Does anyone have a picture that shows the end product, of a custom built x-over project, for a 4343, 4344,4350 type system - Thanx in advance Rick http://audioheritage.org/vbulletin/images/smilies/banghead.gifI guess I could send you a picture when I'm done building yours...

saeman
08-29-2005, 07:17 PM
I guess I could send you a picture when I'm done building yours...

Ah Lancer - you are still out there. On the subject of the x-overs we discussed for my JBL-NOT 4351 project - I need to respond to your request for the 3107 bolt pattern and this post has just remined me of that - will get it shortly. I was unable to PM you so tried regular email. Has your email address changed??? Rick

Lancer
08-29-2005, 07:52 PM
I just answered your emails briefly. I'll look at your emails more closely tomorrow night and answer them more fully.

Ian Mackenzie
08-29-2005, 09:57 PM
Thanks Zilchster,

Perhaps Rick can be guided by one of a experienced crossover builders...Ummm.

Please note, If you decide to make a full passive network, this will cost at least 50% more due to the large capacitors for the woofer and midrange filter. This will also add to the physical size of the network.

What I am proposing is a neato active solution for the 4344 project with passive charge coupled crossover for the mid- horn, horn-uhf transitions. IMHO and based on my recent experiements this will give very impressive results without breaking the bank.

The crossover is the heart of any loudspeaker and the results at the end of the day are a careful balance of design, implementation and cost.

Ian

Ian Mackenzie
08-29-2005, 09:58 PM
I guess I could send you a picture when I'm done building yours...


Agreed,

Ian

Ian Mackenzie
08-29-2005, 09:59 PM
Rick,

How are those boxes going?

Ian

saeman
08-30-2005, 08:28 AM
Rick,

How are those boxes going?

Ian

Hi Ian

Have one baffle complete with mid-base box mounted and all holes cut. Need more 1" P.B. and have it ordered. In 10-14 days I should have a prototype cabinet done and ready for veneer. Here's a revised dwg. I moved the rear panel recessed area down towards the center. Plan "A" left a real tight clearance between the mid driver and the cabinet back, with the recessed area at the top of the cabinet.

The recessed area is 15" high, 23" wide and 3" deep. This should be enough room to mount x-over components/boards. I'll bounce this off Lancer before I cut any wood to final dimensions.

My best to you as always - Rick

saeman
08-30-2005, 09:40 AM
Please note, If you decide to make a full passive network, this will cost at least 50% more due to the large capacitors for the woofer and midrange filter. This will also add to the physical size of the network.Ian

I really don't have the choice of not going full passive on the networks for my 4344 project. The only room I have in the house that has electronics to support a bi-amped/active x-over system is my family room (my turf) and that room is home to my 4350's currently and eventually the 4351's. Going full passive on the 4344's will allow me to put them in any room without needing the extra space for support electronics. To this date the WAF factor has never been an issue. Moving a big full blown system into the living room (her turf) could very well knock a hole in the dike!! Rick

Ian Mackenzie
08-30-2005, 01:24 PM
Ah Ha...now I see sez I...the waf factor....

Ian

Ian Mackenzie
09-03-2005, 07:49 PM
While deemed the obvious we should also do a section on setup and placement.

There is some confusion about the slot being on the ineer and outer edge?

I was having a good listen last nigh before going out on the turps (Saturday night) and it is crucial to this style of monitor that they be palced correctly to ensure not only good imaging, but that the system sounds balanced.

The latter issue is that if toed in too much, you loose the imaging in the extreme highs and the horns can become too prominant.

Ed,

Have you had an opportunity to update the MS Word dcoument yet.

Also, I have requested Unwound (aka Edgewound ~Ken) prepare some posts on driver maintenance, perhaps Techbot will also offer some information of a techincal nature as this is the first topic on the agenda.

If possible I would like to see this posted in the design forum in this month ((September) and we can then rollover the other topic progressively.

Ian

Ian Mackenzie
09-04-2005, 06:21 PM
Rick,

Have you thought of installing a couple of plate amps on the rear and bi amping
(or just bolting a stero power amp to the rear......given the cost of power amps (Parts Express) I image the full passive would be perhaps more so.

The active crossover an be anything ...a small black box....

Only one mains cable and one signal cable and your on cloud Nine.

So much more for so much less (done right of course..I would help you with that!)

I revisited this as I am so pleased with the most recent advances I have made in bi amping that passive mode now seems far less attractive.

Ian

Tom Loizeaux
09-04-2005, 09:15 PM
After thinking about Ian's mention of correct slot tweeter placement, I pulled the grille frames off my 4343s and noticed that the nameplate is positioned directly over the upper half of the 2405s! These aluminum plates span the width of the grille frame and are positioned to completely block the upper half of the slots vertical horn! How could this meet JBL's approval?
I think I'm going to have to remove these nameplates...at least until I'm convinced that this was either intentional...or that it really doesn't matter!
But really, why do we worry about toe-in or tweeter height relative to listening postion when the 2405s are partially blocked?
How could JBL allow this? I'm puzzled.

Tom

Robh3606
09-04-2005, 09:34 PM
"But really, why do we worry about toe-in or tweeter height relative to listening postion when there are largly blocked?
How could JBL allow this? I'm puzzled."

That's odd to say the least that they are blocked by the name plate?!! I run my clones naked with no grills and toe in and height do indeed make a difference. Why they are blocked??? Any doubt dump the grills and see for yourself.

Rob:)

Ian Mackenzie
09-04-2005, 09:36 PM
Ha,

A lot of engineering effort went into the position of those name plates...LOL.

I doubt if many people use them with the grills on.

Tom this is an interesting issue....have you tried with the grills on/off to verify any change ?

Ian

porschedpm
09-04-2005, 09:41 PM
Move the nameplate to the opposite side.

B&KMan
09-04-2005, 10:25 PM
Ah ,

Bo's in charge on The JBL Blue Paint Mixing and Jean is The Sand Man.

Ian



:beach:

mmmmmmmmmmm... HEY pict !!!



well, directly on my beach, I catch a strange vibration on other side of sea...

and I read a couple of point of view on botton Lf case and positionning driver and....


OH OH where is come ...



a 4348 model!!!


I looking the level of doors sky for past of 4343 level to 4344 level and I feel a few reserve...

the alnico driver is better than ferrite driver but the new diaghram expose better upgrade performance. so my opignion is the old driver alnico with new diaghram is expose better flat response and low distorstion due to fatigue material.

the cancellation of back switch (single or bi-amp) is not exposed on upgrade list but it is a top of the line upgrade in regards of the price and influence of LF response!!!

the re-design cabinet on 4343 is not easy question... and my eyes is wait the solution but the 4348 expose the same position of event port !!! so if you rebuilt completely the front and feel to upgrade driver for recent technology: the 4348 model is looking better no ???

In fact, the new drivers is appear realy improvement... and the introduction of Ultra-Uhf is very interesting...


for the front panel, the hard-wood plywood is really improvement of the MDF...

:cheers:

B&KMan
09-04-2005, 10:37 PM
Does anyone have a picture that shows the end product, of a custom built x-over project, for a 4343, 4344,4350 type system - Thanx in advance Rick http://audioheritage.org/vbulletin/images/smilies/banghead.gif

look my avatar pict or go to "4343 crossover modification" thread. for full pict interaction.


:beach:

porschedpm
09-05-2005, 12:49 PM
Attached below is the latest revision of the framework for this project. We've added sections on basic setup and speaker placement and a section on improvements that can be made to the cabinets. We've also added an open ended section at the end for members to describe their more exotic modifications to their 4343 based monitors' drivers, cabinets, crossovers, etc.


Upgrade Modifications to the JBL 4343/4343B Studio Monitors:



This thread will describe several different upgrades available to owners of 4343 and 4343B Studio Monitors. Although we are focusing primarily on upgrades to the 4343 series monitors, owners of other Studio Monitors, 4344, 4350, 4333, etc, will find that many of these upgrades could apply to them also. The upgrades will be broken down into various upgrades starting with relatively simple upgrades up through a full upgrade of the drivers and crossovers. The basic framework here is to offer modifications that improve the performance of the 4343/4343B monitors while preserving their vintage appearance. A requirement here is that the speakers continue to look original. Therefore we will avoid any modifications to the cabinets or grilles. In addition, it is not within the scope of this thread to discuss how to restore the cabinet or grills. There are numerous other threads on the LH Forum that cover these aspects in great detail.



Setup and placement

1. Amplifier power recommendations

2. Connections

3. Room acoustics and monitor placement

4. Slot Tweeter placement- inner vs outer

5. Removing the top baffle

6. Measuring performance.



Upgrade 1 System Maintenance:

1. Clean L-Pads, replace if necessary

2. Clean/improve terminations.

3. Testing condition of drivers and crossovers

4. Recones, refoams and new diaphragms.



Upgrade 2 Upgrade 4343 drivers to 4343B spec.

1. Replace 2231A with 2231H

2. Replace 2121 with 2121H



Upgrade 3 Bypassing the bi-amp switch.



Upgrade 4 Upgrade the stock crossovers.

1. Replacing capacitors.

2. Bypass Capacitors

3. Charge coupling

4. Upgrade crossover to 3145 spec.



Upgrade 5 Discussion on Bi-amping.

1. Pros and cons.

2. Active crossovers available on the market



Upgrade 6 Upgrade drivers to 4344 spec.

1. Replace or recone LF drivers to 2235H

2. Replace or recone MF drivers to 2122H

3. Replace or rediaphragm HF compression driver to 2425J.



Upgrade 7 Converting to Hi End Crossovers.

1. Internal vs External placement

2. Passive

3. Active



Upgrade 8 Cabinet Upgrades

1. Improve internal bracing.

2. Modifying the top 4343 baffle

3. Modifying the bottom 4343 baffle

4. Cabinet and grille repairs



Upgrade 9 Discussion on modern drivers.

1. Modern driver choices available today

2. Use of a subwoofer.



Upgrade 10 Other Upgrades.

1. External Horns

2. 4345

3. Other upgrades

Ian Mackenzie
09-05-2005, 02:35 PM
Great,

Well that should keep us busy for a while.:)

Ian

B&KMan
09-06-2005, 08:12 AM
hello porschedpm,


I attentively looked your list and after my great adventure on my stock 4343
(see 4343 crossover modifications Thread http://www.audioheritage.org/vbulletin/showthread.php?t=1388 ) , I leaves to be humbly made certain modifications with your list of step of levelling.



just before:

By definition a levelling exposes an improvement of design (form or
parts).

The setting in phase in the part and the various aspects which are
attached to it are in fact an optimization... cleaning and the
checking not being a levelling either...

Therefore,

With regard to the levelling:

=======================================
1 --- it is clear for me that the first thing is to put of better
connectors and to cancel the switch Bi-amp. Undoubtedly simplest and one of best levelling to make.

=======================================
2 --- The tiredness of the diaghram requires a replacement most of
the time. After 30 years, several diaghram owed beings installed on the 4343. To supervise, most of the time the former owners put copies of diaghram rather than
originals...
And because with share the UHF no diaghram of origin is
available: The choice of replacement will be according to the ambition of the
levelling.

the basic levelling will be:

-- le 2231 by diaghram 2235
-- le 2121 by diaghram 2122H
-- le 2420 by diaghram 2421 or 2425J (according to the preferences titanium or aluminium)
-- le 2405 by same diaghram 2405

Obviously if you plan to change the drivers, this list is useless.

=======================================
3 --- Levelling of the Condensers and resistances. The ordinary quality of resistances and the old age of the
electrolytique capacitors you ensure a good loss which is reflected on
all the drivers. A change by audio of Solen type or similar metalized polypropylenes will enable
you to feel a good improvement. To try to put the films and foils metallized or better on the high frequencies and to circumvent the large values of low by still of the films and foil. Another improvement is to put the networks outside the cabinet to expose it to less of vibrations. My experiment is that the 3145 diagram is not very powerful with the diagram sof origin thus if you made not the levelling, avoid remaking the network...

Thus your improvements will be maximized... and you will have
perhaps even exceeded in certain aspects the 4344 (since the diagrams
are of more recent technology). your 4343 will sound to the maximum of their prowess without you to cut the throat of the account of bank.

=======================================
4 --- If the heart feel to modify your 4343 more why go worm the
4344 whereas very recently the exercise at summer made by JBL even by
the 4348!!! Time and the money which you will spend to optimize design who also
goes back him to 30 Years to me seems finally profitable compared to a
levelling to 4348...
Moreover the drivers advantage of old is the
alnico five... To replace by ferrite seems to me a retreat... The specialized reviews
of Europe and Asia regard the alnico as superior with ferrites.

to replace it

--- 2231 by 1500FE
--- 2121 by 2251J

to add Ultra Tweeter JBL 045 TI and a network to adjust with the
sensitivity and here....

More still???

Remade a Russian top of face in plywood and install in the place of HF
and UHF a JBL 435A and integrate a JBL 045 TI and you have almost
that one 4348...

build the network in cd. now Charges with reels and condensers
with the height of your madness and here is a solid levelling and will
start again your 4343 for another quarter century....

(BTW I have nothing big surprise if JBL sale this upgrade for studio Owner. )


N.B.
The question of Bi-amplification, of subwoofer or another addition seems me to raise more of the question of the overall system that of a levelling...

I hope that my point of view will be useful to all in this quest of music...

Jean

Ian Mackenzie
09-06-2005, 03:29 PM
Thanks Jean,

The above agenda is bullet points for clarity.

All your points will be thoroughly discussed at each stage.

Ian

porschedpm
09-06-2005, 09:59 PM
Hi, Jean. Thank you for your good observations. I also found it very tempting to want to jump ahead and describe what I feel the ultimate modern iteration of the 4343 monitor would be. However, as Ian pointed out to me over and over again, we want to appeal to as many 43XX owners as possible and so we need to break the upgrades (levellings as you call them) into smaller sections because not everyone will want to perform all the upgrades. Some owners may be satisfied with performing only one or two upgrades. On the other end of the spectrum, others will want to essentially build the ultimate 43xx derivative based on all modern drivers and modern crossover technology. We wanted to structure it so 43xx owners could pick and chose the upgrades they feel comfortable performing and also layout the structure so that each progressive upgrade is a little more extensive than earlier upgrade. We also decided early on that there are certain controversies that we will want to avoid. One of these is what brand internal or external wire is the best to use. Another is the Alnico vs Ferrite debate. These are both subjects for which many differing opinions abound and to get into these debates here can quickly confuse the purpose of the project and polarize the members. I know that you have a lot of experience already performing upgrades to these monitors and crossovers and I look forward to your continuiing contributions to the project.

Ed

B&KMan
09-06-2005, 10:43 PM
Hi, Jean. Thank you for your good observations. I also found it very tempting to want to jump ahead and describe what I feel the ultimate modern iteration of the 4343 monitor would be. However, as Ian pointed out to me over and over again, we want to appeal to as many 43XX owners as possible and so we need to break the upgrades (levellings as you call them) into smaller sections because not everyone will want to perform all the upgrades. Some owners may be satisfied with performing only one or two upgrades. On the other end of the spectrum, others will want to essentially build the ultimate 43xx derivative based on all modern drivers and modern crossover technology. We wanted to structure it so 43xx owners could pick and chose the upgrades they feel comfortable performing and also layout the structure so that each progressive upgrade is a little more extensive than earlier upgrade. We also decided early on that there are certain controversies that we will want to avoid. One of these is what brand internal or external wire is the best to use. Another is the Alnico vs Ferrite debate. These are both subjects for which many differing opinions abound and to get into these debates here can quickly confuse the purpose of the project and polarize the members. I know that you have a lot of experience already performing upgrades to these monitors and crossovers and I look forward to your continuiing contributions to the project.

Ed


Boujour with you also,

(sorry fo bad traduction of upgrade = leveling (mise niveau => in french)

I account of the objectives and the stages goes well to present, however the choice even of unquestionable upgrade can be discustable
in discussion in depth. I believe that your company is extremely creditable and this is why I have to decide to expose you my opignion on the step and not on final solutions from the beginning.

My intervention humbly aimed at clarifying certain aspect slipping ex: the multiple change of drivers to wire of the upgrades can in end line
expensive and investisement to represent frustration and bad being...

so maybe the best title is " procedure for upgrade your 4343" (not necesary at 4344) or

" any you want about improvement your 4343 !!!"


Lastly, however, I say yes at your project and I will try as much as I could provide my small contribution.

Ian Mackenzie
09-09-2005, 06:20 PM
Jean,

Are you able to post a picture of the biamp switch?

Thanks

Ian

B&KMan
09-09-2005, 10:22 PM
Jean,

Are you able to post a picture of the biamp switch?

Thanks

Ian

it is OK for you ???

:cheers:


BTW check carrefully this swich is already bypass : look manys cable is cut at 1 inch of the switch connector and the yellow twist cap is normally not there.

In fact I have a another modification on pict : the post speaker is a modified.

finally look carrefully the color of brass of switch : corroded !!!!

so the really big improvement for pennies is cancel this
(see difference curve in thread " modification 4343 corassover "

:cheers: again !!

Jean. :D

Ian Mackenzie
09-09-2005, 11:14 PM
Thankyou Jean,

A picture tells a thousand words. :blink:

Ian

Tom Loizeaux
09-10-2005, 08:32 PM
I've thought about what detail I might be losing because of this rotary switch and have considrered bypassing it since I only run my 4343s in the bi-amp mode. I don't, however, want to clip the wires. Being able to return this to stock is important to me.
If it's possible to "jump" the switch by soldering in short copper wires between certain terminals and make it run in the bi-amp mode, I'd be intertested.
Can anyone make a drawing of this switch showing how to jump it for semi-permanate bi-amp mode?

Thanks,

Tom

Zilch
09-10-2005, 08:53 PM
Hi, Tom.

It's fairly easy to determine upon examination which leads should be jumped with the switch in the desired position.

In the photo above, for example, terminals 2 and 3, 5 and 6, 8 and 9, and 11 and 12 are connected. The second wafer should be the same.

I'm not sure that's the desired position, but you get the idea....

B&KMan
09-10-2005, 11:23 PM
I've thought about what detail I might be losing because of this rotary switch and have considrered bypassing it since I only run my 4343s in the bi-amp mode. I don't, however, want to clip the wires. Being able to return this to stock is important to me.
If it's possible to "jump" the switch by soldering in short copper wires between certain terminals and make it run in the bi-amp mode, I'd be intertested.
Can anyone make a drawing of this switch showing how to jump it for semi-permanate bi-amp mode?

Thanks,

Tom


Hello Tom,

Actually this picture above is expose modification for single amp.

but the best for you is to cut wire at half inch.

(same as pict.) and you connect cable with-out switch. many secondary cable is link join of switch to other link switch.

if you cut and bypass all connection you perform simply and shurely bypass.

create schematic before and if you downgrade for stock it is easy to soldering cable to cable.

but for me it is impossible to go back !!!!

why ???

After analyser, the switch is too much poor connection signal.

the next link expose my pict of before and after cancel switch.

the result is expose clearly the really poor transfert linearity.

http://www.audioheritage.org/vbulletin/showpost.php?p=51750&postcount=101

http://www.audioheritage.org/vbulletin/showpost.php?p=52144&postcount=113

at this time test, I haved not good undertand of design network and english...

So I hope the proof is clear in this aspect and you perform soon as possible the better and simple upgrade in your 4343....

:cheers:

Jean.

B&KMan
09-10-2005, 11:39 PM
In Other hand I'm sorry ,
My picasso talent and my not interest for bi-amp dont push me to keep specific layout.

see my pict bulded in couple of years and you understand why the computer is a beautiful machine...

:D

:cheers again:

Ian Mackenzie
09-11-2005, 04:00 AM
As of today I will no longer be formally involved on a day today basis with the Forums.

The responsibilities and the many commitments I have here far outweigh what I have left to give and after a time there is a tendency to grow short of head space in the face of apathy and contempt.

I have however greatly enjoyed being on the forums and wish you all well in the future. Perhaps I will met up with some of you again some day...America is a great place to visit.

Unfortunately there is just not enough time to do justice to all the projects and at this point I would like to ask Zilch and Lancer to take over this important project to ensure its goals and aims are achieved.

Its is proposed that I will complete the other outstanding projects directly involving other Forums members in the immediate future.

I will pop in from time to time so please keep a seat warm for me boys.

Bye Bye for now

:coolness:

Ian

B&KMan
09-11-2005, 09:37 AM
As of today I will no longer be formally involved on a day today basis with the Forums.

The responsibilities and the many commitments I have here far outweigh what I have left to give and after a time there is a tendency to grow short of head space in the face of apathy and contempt.

I have however greatly enjoyed being on the forums and wish you all well in the future. Perhaps I will met up with some of you again some day...America is a great place to visit.

Unfortunately there is just not enough time to do justice to all the projects and at this point I would like to ask Zilch and Lancer to take over this important project to ensure its goals and aims are achieved.

Its is proposed that I will complete the other outstanding projects directly involving other Forums members in the immediate future.

I will pop in from time to time so please keep a seat warm for me boys.

Bye Bye for now

:coolness:

Ian


Hello Mr. Mackenzie,

this is a large surprise and I hope that what attracts you elsewhere
better than than to you is left.

I appreciated a number of interventions that you made...
And for your division of connaisance and several other tricks which
you liberally shared with me, I thousand times say to you thank you!!!!

even if if too often the barrier of the language induced me in error, and sometimes our divergeance of opignion which in spite of very
brought to a light on the fundamental problems goshawks of vintage speakers JBL.


More than 2000 posts is a contribution of most remarkable with this
forum by a deployment of incredible effort: I pick you up my hat!!!


I wish you a long life happiness.
And I will always have pleasures to read the explanation and comments
of a man of experiment.

thank you for all and thank you still.

Jean.

Rolf
09-12-2005, 06:09 PM
For all of us who are just reading and waiting for a solution regarding these crossovers, witch looks very promising, I must ask: Why did you start this if you have no plan finishising it?? Great disapointment....Or have I missed somthing??

Have a nice day.

Rolf

Ian Mackenzie
09-15-2005, 09:28 AM
Don't mind us, just thought we would stop off at the beach and collect some sand for Jean. Actually, its looks more like pebbles, must have landing a bit too early!

Nice to be back. My predecessor certainly was a bloody pain in the backside and a grumpy old fart don't you think?...Silly old bugger actually, oh and I'm off the booze....

So I have been reincarnated yet again!

Well on with the show, but I really should'nt be attempting to improve these things. That will change the course of history and piss of the historians.....oh well...bother.

Ian Mackenzie
09-15-2005, 09:38 AM
We better have a show of hands who is going to be following this adventure and who might like to contribute some stuff...its SF California casual by the way so relax.

My memory is a bit hazy after that last birthday bash, now where were we?

The New Doctor Who

Ps I doubt if this would make any sense to our American friends, with 99 channels of Frasier, CSI, The Weather Channel and re runs of Mr Ed and Columbo I doubt if they have time to watch anything else.

This is Weird, that's right the whole world is Weird, not just America..:barf:

Ian Mackenzie
09-16-2005, 02:59 PM
Rolf,

There are a number of useful threads on the forums that discuss the 4343 - 4344 crossover.

I am not sure how long you have been following this project thread attempts to discuss and implement not just the crossover but all elements of the system that effect audio performance (refer to the agenda above).

For example I have read only yesterday a thread that responded to a 4344 upgrade. The Hf driver diaphram and crossover where mentioned as the main upgrades.

While this will technically transform a 4343 to a 4344 component spec there are other improvements that will further transform the performance incl updating the front baffle to offset the Mid, Hf and Uhf drivers and an enhanced active crossover design.

Ian Mackenzie
09-16-2005, 03:12 PM
Project status

The prototype class A active crossover has been completed and will be shipped for evaluation (with a JBL 5235 for comparison) by other members around end of September.

Recent listening tests re-confirmed the impact of the active crossover on the system performance.

While I might be biased (sorry..I thought that was funny), you will not find a finner active crossover anywhere in the world. (this one is the only one of its kind in the world so that is basically true!)

I will post pictures shortly.

The New Doctor

Ian Mackenzie
09-16-2005, 03:36 PM
We also have in the wings something I have waiting to complete for several months for this project.

Its rather frustrating when you have lots of ideas and can't find the time to make them happen!

Anyway this device called The Class A Plate amp.

Most of use know a Plate amp as a bolt on amp that is generally used for sub woofers..they are sold by vendors like Parts Express.

This however is a Plate amp with a difference. Its custom designed for the 4343-4344 to drive the mid and Hf sections and will include an customised Class A active crossover tuned to the 4343/4344 and will bolt onto the rear of the enclosure using a bracket I designed.

The Class A Plate amp will offer the benefits of bi amping..without the negatives.

Lots of wires and amps lying around the listening room. Basically a mess you and your wifey don't need. Plus the active crossover will enhance the performance rather than smear the sound as we have found in recent tests.

Because its already set up for the 4343-4344 you don't have fiddle with crossover characteristics (there is amp leveling adjustment) and best of all the audio performance is nothing short of stunning..once you have tried it there is no going back!

This will be rolled out towards the end of the 4343-4344 upgrade project so hang around.

The New Doctor

The crossover...waiting some cosmetic updates.

Rolf
09-17-2005, 05:57 AM
Rolf,

There are a number of useful threads on the forums that discuss the 4343 - 4344 crossover.

I am not sure how long you have been following this project thread attempts to discuss and implement not just the crossover but all elements of the system that effect audio performance (refer to the agenda above).

For example I have read only yesterday a thread that responded to a 4344 upgrade. The Hf driver diaphram and crossover where mentioned as the main upgrades.

While this will technically transform a 4343 to a 4344 component spec there are other improvements that will further transform the performance incl updating the front baffle to offset the Mid, Hf and Uhf drivers and an enhanced active crossover design.

Hi Ian.

Good to read your latest posts. I can only speak for myself and I would be VERY interested in this new crossover. I have no plans of building a new baffel to my 4343B's or changing the elements, but the crossover....Yes.

Please keep me informed via my personal e-mail, or any other way that suits you.

Have a nice day.

Regards

Rolf

Don C
09-17-2005, 08:26 AM
The Lansing Forums appears to be rather lack lacking in interest.
The New Doctor.
I assume that you are talking about the plate amp? I think that we can call this an energiser , using JBL-speak. Anyway, I don't mind running wires from the rack and I have plenty of amps available right now. So no interest here. But I'm still interested in the boards for the two way active crossover though.

Ian Mackenzie
09-17-2005, 03:45 PM
Thaks Rolf,

I will keep you up to date.

Don,

Please pm me you requirements and I will organise it.

DAVID POHLER
09-17-2005, 04:12 PM
Quote:
Originally Posted by Ian Mackenzie
The Lansing Forums appears to be rather lack lacking in interest.
The New Doctor.


Hey Ian:

I think there are more interested parties than you may think. I for one have been actively following the events on this forum for a couple years now; I feel like I know most of you guys. I feel a little intimidated in getting actively involved, especially when it comes to electronics; Im on a third grade level compared to the electrical engineers here. I do however have good taste and a golden ear.

I have a pair of 4343B speakers, like so many others I want them to sound as good as they possibly can. Ive been waiting for the discussions to begin on the various upgrade levels before jumping in. My mistakeI need to become more involved. I appreciate the huge amount of time and effort you are investing in this project/discussion. I guess I need to thank everyone here for sharing their knowledge so openly with complete strangers.

Im not sure how far Ill go with this upgrade project; Im looking forward to hearing all the pros/cons before deciding. Im leaning towards an updated crossover. I am very interested in this forum and will become more involved.



Thanks again,

Dave

Ian Mackenzie
09-17-2005, 04:23 PM
HI Dave,

Happy to have you on board.

About third grade, we thats about where my behaviour is most of the time.

I'm a trouble maker and a pain in the arse and when I am not being good I'm stealing other kids lolly popps....but all the girls love me and I am a teachers pet so thats okay.:rotfl: Heck I should have been a politician.


So If you have a question just fire away...in reality this stuff is based on very simple principles. (its not rocket science)

The New Doctor.

Ian Mackenzie
09-17-2005, 08:48 PM
Quote:
Originally Posted by Ian Mackenzie
The Lansing Forums appears to be rather lack lacking in interest.
The New Doctor.


Hey Ian:

I think there are more interested parties than you may think. I for one have been actively following the events on this forum for a couple years now; I feel like I know most of you guys. I feel a little intimidated in getting actively involved, especially when it comes to electronics; Im on a third grade level compared to the electrical engineers here. I do however have good taste and a golden ear.

I have a pair of 4343B speakers, like so many others I want them to sound as good as they possibly can. Ive been waiting for the discussions to begin on the various upgrade levels before jumping in. My mistakeI need to become more involved. I appreciate the huge amount of time and effort you are investing in this project/discussion. I guess I need to thank everyone here for sharing their knowledge so openly with complete strangers.

Im not sure how far Ill go with this upgrade project; Im looking forward to hearing all the pros/cons before deciding. Im leaning towards an updated crossover. I am very interested in this forum and will become more involved.



Thanks again,

Dave









Dave,

This thread is crying out for some pictures.

We would be delighted if you might post some pictures of your 4343B's.

As an entry point for you to participate if we could post some pictures of the stock passive crossovers we could then work up an action plan for upgrade options.

Please do not be concerned about the implementation... don't be.... there are a number of members who can assist.

The New Doctor

Ian Mackenzie
09-18-2005, 07:20 AM
I've edited selected posts and placed them on the Speaker forums of Diy audio.The 4343 has been discussed over there in a number of threads and some modifications

It will be interesting to gauge the reaction and perhaps it will sattract more participation and some new members to Lansing Heritage forums.

I might even raffle off an active crossover kit to a lucky participant...you have to be in it to win it!

The New Doctor

Ian Mackenzie
09-18-2005, 05:34 PM
Upgrade 3 Upgrade 4343 drivers to 4343B spec.

Replace 2231A with 2231H

Replace 2121 with 2121H

Below are the various iterations of this model in the JBL Studio Series.

And some background information on the ins and outs of the 2231A-2231H and the 2235H.

The best post is here from Don:http://www.audioheritage.org/vbulletin/showpost.php?p=6367&postcount=24

The bottom line is if you have a 2231A, try and find a 2235H. If you have a 2231H, check the recone is A 2235h recone.

As to the 2121A, if you can find a 2121H go for it but they are as scarce as hens teeth.

Other threads with interesting information.

http://www.audioheritage.org/vbulletin/showthread.php?t=6734&highlight=2231H
http://www.audioheritage.org/vbulletin/showthread.php?t=5428&highlight=2231H
http://www.audioheritage.org/vbulletin/showthread.php?t=5144&highlight=2231H
http://www.audioheritage.org/vbulletin/showthread.php?t=790&page=1&pp=15&highlight=2231H

http://www.audioheritage.org/vbulletin/showthread.php?t=2454&highlight=2231H

Ian Mackenzie
09-18-2005, 06:00 PM
Upgrade 4 Bypass the bi-amp switch.

See post 101 106 by Jean:

http://www.audioheritage.org/vbulletin/showpost.php?p=68923&postcount=101
http://www.audioheritage.org/vbulletin/showpost.php?p=69042&postcount=106



Please be aware the colour coding of the wiring in the 4343 is a brain teaser.

Firstly, decide if you intend to biamp or run passive, obviously bypassing this switch will made either mode permanent!

Yoy may also wish to upgrade to superior binding post while performance this update. We will revisit this later I hope with actual images of a step by step guide to bypassing the switch

Ian Mackenzie
09-18-2005, 06:26 PM
Upgrade 5 Upgrade the stock crossovers.

A/ Bypassing capacitors (re route Hf and Uhf signals direct to input terminal)


B/ Replace capacitors. "''' ""

C/ Charge coupling

D/ Upgrade crossover to 3145 spec.

Okay, this is the Juicy post you have all been waiting for...Muhhaha.

A/ Bypassing capacitors (re route Hf anf Uhf signals direct to input terminal)

As we outlined earlier, some of you might just want to dabble and to a large extent preserve the vintage of the 3143 and just make subtle upgrades.

If this is the case I recommend bypassing all the capacitors with Audio Cap PPT Theta 0.01 uf film foil capacitors (Part Number 027-700 available from Parts Express).

Bypassing was essentially the first major impovement JBL did in the evolution of their crossover developement.

While you are at it definately re route the HF and UHF signal directly to the Red input terminal or the input side of the 52 uf capacitor. (see schematic below)

Someone might be kind enough to post a redrawn schematic.


B/ Replace capacitors.

This is a more advanced update and it is open to more user preference for parts. Do not attempt this update A) Without careful planning B) Unless you are confident you have the skills.

It is assumed that the existing stock capacitors will be changed out. It is important that what every you replace them with fits in the existing space.

This may not be the case with some Film foil types.

As to recommendations, I can recommend both the Hovland and Auricaps from personal experience. No doubt there are other good capacitors and some may also prefer to replace and bypass. My suggesting is just go for a really good capacitor if you are attemping to change out the stock parts..you only want to be doing this once.

C/Charge Coupling

This is the next level of upgrade and perhaps the most popular crossover upgrade for the crossover fanatics.

JBL has been charge coupling some of its designs for some time now.The benefits can be found in the Library and on numerous threads on the forums. This upgrade will require building a complete new crossover and again will require advanced skills. If you would like to do this and are not confident to doing it your self there are members on the forums who may be able to offer assistance for a fee.

I would pitch this upgrade with the option of going to the upgrade to stock 4344 crossover (3145) as there are design benefits to be had in this iteration and they go hand in hand with the driver upgrade to the 4344.

I do not have schematic of a charge coupled 3143 so if there is interest here someone might be kind enough to post a schematic.


D/ Upgrade crossover to 3145 spec.

As mentioned above this upgrade assumes you intend to upgrade your drivers to the 4344 spec (the 2231A - 2235H , 2121A to 2122H and 2420 to 2425J)

Essentially the same rules apply as in upgrade C.

This crossover is even more advanced and has different characteristics to match the 4344 drivers.

The 3145 network however uses parts no longer avaialble. Fortunately there is an equivalent network to the original stock 4344 (3145 crossover) designed by Giskard (JBL Lansing Heritage Forums Guru). There is also a further refinement of this original stock crossover in the forum of a new equivalent 3145 network that has been developed recently by Giskard.

They can be built using film foil capacitors, bypassed film foil or charge coupled.

It may also be an option to locate these networks external to the enclosure due to their size and for purely acoustic reasons.

I will post a schematic later.

So you have lots of options and each will appeal to one member or another for different reasons.....

More to follow;

The New Doctor

Zilch
09-18-2005, 07:09 PM
Those desiring to retain the switching capability, but wanting to upgrade to a new and better enclosed switch might consider this:

http://www.electro-nc.com/rotaryus/c4.pdf

$20 from Newark Electronics, but you may have to work out your own shaft extension or custom knob....

Ian Mackenzie
09-18-2005, 07:20 PM
If you have to have switching (I am not sure why that might be) that is always a possibility. Thanks Zlilchster.

But essentially its another junction the signal has to cross...electrons hate jumping from one condutor to another.

Ages ago Speaker Builder did a revamp of the 4333, the switch was sighted as degrading audio performance.

Ian Mackenzie
09-18-2005, 07:36 PM
Upgrade 6 Discussion on Bi-amping.

Pros and cons.

Active crossovers available on the market;

Okay we have prevous gone over this but for the record biamping improves bass clarityand provides improvements in dynamic range (but there is a downside)

http://www.audioheritage.org/vbulletin/showpost.php?p=67493&postcount=61

Refer to the crossover updates to re route the HF and UHF driver signals and you will notice further improvements.

If however you are currently running full passive mode and have only one amp I encourage you to do the crossover and other upgrades and note the improvements before proceeding to bi amping.

Unfortunately, the fidelity of all but the most premium of active crossovers degrades what may be termed the HiFi aspects of the sound quaility. This will be more noticable if you have premium grade amplification (such as a Valve amp like a Cary, Audio Research a Passlabs or other cut above average amps).

If you are considering your options, your strategy might be to spend funds on a good crossover upgrade (plus the other updates) and enjoy the benefits of improved timbre and clarity and transparency as being more important than the last ounce of bass definition.

You may even then go for a better amp.

One interesting comment that has surfaced on the diyaudio forums:

Interesting project, Ian.

I must admit, the "shoutyness" that you have had success in removing, seems to very much be part of the JBL house sound, even affecting their PA boxes and install systems like the Control range. In the Brit audio industry, it is always known as the "American" sound.

Yet, it doesn't seem to be a characteristic of the JBL drivers that I have listened to individually, so your experiences of crossover reworking removing this is facinating. The question has to be "Why that voicing"? http://www.diyaudio.com/forums/images/smilies/wink.gif


__________________
Al



Our subjective comparisons in the development of the project suggest this is very much the case.

On the other hand if you want a loud, snappy and dynamic sound and can live with some loss of transparency and brassy tonality then go for biamping. For what ever reason this is a namesake of the 4343 historically but we're about to change all that.

It is surprising how well the JBL 4343 upgraded to the 4344 spec can etch out the impact of ampifiers and associated electronics on the original signal.

In summary its a lot more difficult to get the best of both worlds with biamping but if you really have to have it then keep following this thread.

The New Doctor

Tom Loizeaux
09-18-2005, 07:47 PM
I've thought about what detail I might be losing because of this rotary switch and have considrered bypassing it since I only run my 4343s in the bi-amp mode. I don't, however, want to clip the wires. Being able to return this to stock is important to me.
If it's possible to "jump" the switch by soldering in short copper wires between certain terminals and make it run in the bi-amp mode, I'd be intertested.
Can anyone make a drawing of this switch showing how to jump it for semi-permanate bi-amp mode?

Thanks,

Tom

Ian Mackenzie
09-18-2005, 07:52 PM
Good point Tom,

Lets explore this a bit futher and see what we come up with.

Time for a tea break.

Over and out.

Tom Loizeaux
09-18-2005, 08:06 PM
I, too, am interested in your "powered crossover" for the 4343.
Please keep us posted.

Tom

Ian Mackenzie
09-18-2005, 10:47 PM
Okay I will note your interest.

Should there be enough interest in this particular device I will set forth and do a one off production run.

While not wishing to elaborate to much at this point it will be minimalist black box so to speak for the 4343-4344 owner "only" but full of very nice goodies and with a few tricks I've got up my sleeve....

The New Doctor

Ian Mackenzie
09-18-2005, 11:00 PM
Upgrade 6 Upgrade drivers to 4344 spec.

1. Replace or recone LF drivers to 2235H

2. Replace or recone MF drivers to 2122H

3. Replace or rediaphragm HF compression driver to 2425J.


1 Well I have discussed that to death above.
2. The 2122H is an upgrade of the 2121 and according to Giskard and others a better driver.

Here are a number of links that will answer all your questions and more!

http://www.audioheritage.org/vbulletin/showpost.php?p=8486&postcount=11
http://www.audioheritage.org/vbulletin/showpost.php?p=8482&postcount=7
http://www.audioheritage.org/vbulletin/showpost.php?p=7395&postcount=4
http://www.audioheritage.org/vbulletin/showthread.php?t=39&highlight=2122H
http://www.audioheritage.org/vbulletin/showthread.php?t=93&highlight=2122H
http://www.audioheritage.org/vbulletin/showpost.php?p=546&postcount=2
http://www.audioheritage.org/vbulletin/showpost.php?p=53291&postcount=3
http://www.audioheritage.org/vbulletin/showthread.php?t=4379&highlight=2122H
http://www.audioheritage.org/vbulletin/showthread.php?t=751&highlight=2122H
http://www.audioheritage.org/vbulletin/showthread.php?t=3604&highlight=2122H
http://www.audioheritage.org/vbulletin/showthread.php?t=1616&highlight=2122H
http://www.audioheritage.org/vbulletin/showthread.php?t=89&highlight=2122H

3. This is an interested upgrade.

Firstly, if you own a stock 4343 I would think twice about pitching out the 2420 for the 2425J. Some members have reported better sonics from the Alnico 2420/2421.

Secondly, I am not sure if the upgrade to 2121 aluminium diaphragm is still available as a spare part from JBL, I know they are around on E bay sometimes......someone might want to check this out.

Regardless either is better than the original 2420 diaphragm.

The aluminuim version of the diamond surround diaphragm apparently sounds better. If you are really keen you might want to sniff out the aquaplas coated 275nd diaphragms. There might be some technical variations but I think the results would be rather tasty.

The issue with these things is mass, stiffness and self damping....much like any other driver actually.

There are a number of threads that explain how these diaphragms work and so on and so forth.

Please arrange the upgrading of the diaphragm by a JBL authorised service centre. Edgewound is one Authorised JBL service agent I am aware of on the forums although I have not heard much of him lately.


My recommendation is don't do any driver upgrades yourself, just call your local JBL service agent and tell them what you need.

Ian Mackenzie
09-18-2005, 11:03 PM
Upgrade 7 Converting to Hi End Crossovers.


1. Internal vs External placement

2. Passive

3. Active

1. Internal vs External placement

The theory and to some extent subjectively some listeners say that external crossovers sound better. I have never seen any scientifically conclusive analysis that confirms this one way or the other however I know from personal experience external crossovers do sound in some instances different. There is an apparent deeper silence between the notes and the speaker tends to sound more clean and precise.

It also depends on how far you want to go. Some say if you can carefully hot melt glue the crossover parts down on a backing board they will not vibrate much. This is where a bit of black art comes into play.

I would also point out that due to layout considerations however, internal crossovers tend to be cramped up in a small space and therefore compromised. Putting everything in na confined space is not always ideal electrically for the filter to perform at their best due to mutual coupling of coils and isolation of filters from one another due to poor wiring layout.

The design of a external crossover is more likely to perform to the ideal due to less practical/physical limitiations of layout.

In the case of the charge coupled networks I would suggest this is welcome due to the complexity invloved.

If you do plan on an external network you will need to arrange a suitable means of cabling to the outside world. I used an 8 Pole Speakon Plug and Socket. There a several advantages with this style of connector, its air-tight, has very good electrical characertistics, takes a 13 gauge cable and the polarity of the individual driver cabling is identified and maintained without fear of error.

Phasing errors are by far the single biggest issue with reworking a multiway network.

You can place the external crossover on the rear of the speaker or in its own dedicated enclosure if you wish.

HI End Passive Parts.

Well, the skys the limit here and I have had many members ask for recommendations. There are dozens of brands, Auricaps, Mundorf, Hovlands, Cardas, Audiocap and North Creek to name a few.

The use of Solen fast caps bypassed with hi quality film foils and charge coupled is also another avenue as used by JBL.

In this respect its a trade off of complexity versus cost.

Ideally the cost of crossover should account for 1/3 the total cost of the system according to one speaker builder author. So if the bill of parts appears expensive don't finch..its the way it is. Just don't tell your wife.

Mills resisters are preferred for in signal path locations. Coils should be chosen based on the specific electrical characteristics. Do not use iron laminated cores unless specified.

Wire, well I am not even going to go there, use common sense. Wire gauge should be proportional to current.


Active

We have discussed this above. If you propose to layout a fair amount of cash on passive crossover parts don't expect a miracle with bi amping unless your unit is up to spec. Otherwise go full passive. The JBL 5235 and the Ashly active crossovers for what they are aren't bad but are not deserving of any crossover upgrades discussed in this project.

Using high quality capacitors and all the other updates we have discussed will absolutely improve the transparency of the loudspeaker. But it will also let through the warts and all.

All the stuff upstream has to come down stream, if its dirty it will stand out like dogs balls. You will hear the impurities in the form of sonic glare or a cloudy haze, the bass lacking definition and the loss of fine details and ambiance.

This is why I have been referring back to a total system approach. Just pretend you are a UK or Japanese Hifi nut but on an industrial scale.

Ocassionally I have seen some nice units on audiophile review sites but they are few and far between. The DEQX is promising but for $3K its not cheap and a lot of wasted horse power if you are not a speaker designer wizzard.

I will give the idea of organising a package based on the my class A discrete crossover some thought if there is sufficent interest. As mentioned above it will be be a minimalist purpose built limited edition Hi End crossover for the 4343-4344.

Everything has to be in balance.



http://www.audioheritage.org/vbulletin/showpost.php?p=66848&postcount=50

Ian Mackenzie
09-19-2005, 02:45 AM
Upgrade 8 Cabinet Upgrades

1. Improve internal bracing.

2. Modifying the top 4343 baffle

3. Modifying the bottom 4343 baffle

4. Cabinet and grille repairs


Please refer to the images below.

It is best to limit this discussion at this point until members come forward and provide input on what they would like to do. Obviously there will be limits with what you can do with an exisiting cabinet. Some may even go the the extent of re building the enclsoures...bravo to that cause!

http://www.audioheritage.org/vbulletin/showpost.php?p=66700&postcount=41
http://www.audioheritage.org/vbulletin/showpost.php?p=66702&postcount=42
http://www.audioheritage.org/vbulletin/showpost.php?p=66700&postcount=41
http://www.audioheritage.org/vbulletin/showpost.php?p=66702&postcount=42
http://www.audioheritage.org/vbulletin/showpost.php?p=66712&postcount=44

Ian Mackenzie
09-19-2005, 03:11 AM
This series of post has been mainly descriptive of the specific updates to flesh out the what, why and how.

The intention is to use work in progress on members own systems as the discuss focus from here on which will when completed be posted in edited form into the 4343-4344 design thread.

That way everyone who wants to particpate with a specific upgrade has the opportunity to show and talk about what they are doing and share ideas and experiences with each other.

It should all be a lot of fun, that after all is why we are here.

The stats ...134 posts and 2956 views......I told you I would not babble on to much....LOL

Ian Mackenzie
09-19-2005, 05:42 PM
Upgrade 9 Discussion on modern drivers.

1. Modern driver choices available today

2. Use of a subwoofer.

1. Modern driver choices available today

Well modern driver choices comes down to availability, cost and skill of the builder / designer to come up with a crossover network that will ensure the drivers work correctly together. This has previously been a stumbling block for Forum Members who have attempted to use more recently developed JBL transducers only to be frustrated with their attempts at arranging a successful crossover network.


We therefore suggest and in keeping with the 4344 design criteria that members looking for a taste of newer technology look at cloning or modifying their 4343 to the JBL 4344mk11. Details of the 4344mk11 crossover network are available for interested members. The mid range driver used is the 2123H.

With the exception of the woofer and HF driver the components are available.



Woofer and Hf driver alternatives.

The suggested work around for the woofer is to recone the 2235H woofer as a 2234 with a 2234 recone kit and apply some LF Eq boost. This will provide sensitivity of around 95 db and an extended cutoff per the 4344 series. The 2234H has a lighter Mms and is the preferred woofer over the 2235H by some JBL engineers.

The 275Nd compression driver is NLA. However I understand the 275 diaphragm is still available and it will fit the 2420 driver.

The enclosure is identical to the former 4344.

Other more daring members may look to using an alternative horn like the PT wave guides or a mini 2397. Again, you will need to fiddle with the crossover network to obtain the desired performance.


4348 Drivers
Edit Note: As advised by Earl:

From the look of it, JBL is now starting to take orders for these SOTA parts.
( BTW ; these are 3 of the 4 parts for the 4348 4-way ) The 2251j is already available from JBL Pro .
- It seems the ME150H is no more , but is being replaced by the 1500Fe, for the DIYer. ( This is excellent pricing BTW ) .

So here is another opportunity to take up nre technology.



2. Subwoofers.

Unless you are a home theatre buff or have unusual room acoustics a sub woofer is not required nor desirable with this system for music reproduction.

Sub woofers are fun but difficult to integrate successfully for full range music reproduction. Such is the case that many people end up turning the sub off after the initial enthusiasm as worn off.

The JBL 1500 sub woofer driver has been very popular among members.

There are numerous threads on the forums that discuss the 1500.

Ian Mackenzie
09-19-2005, 06:05 PM
Upgrade 10 Other Upgrades.

1. External Horns

2. 4345

3. Other upgrades

1. External Horns

Some members have taken to using external horns for the JBL home speakers.

Its an easy way of playing around with alternatives.

One popular horn that comes to mind is the 2397. This horn however works best with a large format compression driver like the 2440/2441/2445/2446.

On issue with using external horns however is the vertical height of the external horn above the other drivers and the listeners ears when sitting atop the enclosure.

The 4343 enclosure is designed such that when seated the HF horn and Slot radiator are at the correct height. In this instance the external horn will need to be tilted forward if practical to ensure adequate vertical coverage angle although this may compromise other aspects of the system preformance.

Some adjustment of the crossover maybe required to attain the best results.

2. 4345

There a a couple of extensive threads on this monitor, essentially an 18 inch woofer version of the 4344.

The enclosure is significantly larger than the 4344 but the system is an interesting candidate for those seeking effortless bass!

3. Other upgrades

I know of one member who claims to have improved the perfomance of the horn by wrapping a sound absorbant layer of damping material around the 2307 horn. The intent being to damp any resonances within the aluminium casting.

Other members have resorted to sand boxes and concrete slabs under their systems where floor coupling may effect the quality of bass reproduction.

Ian Mackenzie
09-19-2005, 06:14 PM
Well that's about it from me.

As I mentioned earlier I don't like loose ends and revisited the Lansing Heritage Forums especially to complete this project thread.

Please send me Pms for any questions or ideas you may have and I will do my best to answer them in a timely manner. I will also look into the class A active crossover and get back to those who are interested.

I will be doodling over on diyaudio.com building a class A plate amp if anyone wants to come and say hello.

The New Doctor

Ian Mackenzie
10-23-2005, 08:23 AM
Probably a good idea to cover setting up:

1. Setting the L Pads- I'm not going to repeat myself ..this is critical and you need some if only basic test equipment. Can't be done poperly with your ears.

When this is done the system should perform as one driver.

Somewhere there is a thread in which I outlined a simple proceedure..it works.

2. Placement - Also critical for best performance. The slot radiator must be at ear level. If your ear height is a little bit lower or higher the cabinet can be titled slightly with some packing.

The enclosures must be arranged in exact symmetry within the room.

They should be toe'd in about 10-15 degees (no more). The slot radiators should be on the outside.

When this is done correctly the system will reveal precise stereo imaging and front to back depth.

Anyone who can't get this to happen should buy a Walkman, sell their 4343-4344 to forget about it.

The limiting factor will be the room, the source and amplification.

3. Equalization- This is not absolutely necessary if the above steps are executed correctly.

Even the best equaliser will add noise and distortion to your enhanced 4343-4344. If you believe you need an equalised response attempt to correct the issue with placement and or room treatment. Seek professional advise of you have a particular room issue.

There is no snake oil or hidden mirrors regards setup. But setup has an influence of about 30- 50% of the subjective performance, the other 50-70 % is what the room does to the sound.

I have professionally heard the system in the worst and the best acoustic environment. On a scale of 100 the difference was 1 versus 100.

I spent an hour today performing the about steps and the results are outstanding.

On high quality recordings the sound stage as such does not exist, instruments and voices just appear as individual objects in space and are easily differentiated.

Of course the best amplifiers, active crossover and source you can afford will add the ultimate refinement in musical satisfaction.

Enjoy.

yggdrasil
10-23-2005, 03:12 PM
Here's the setup procedure: http://audioheritage.org/vbulletin/showthread.php?t=6345&highlight=spl

Tom Loizeaux
10-23-2005, 09:34 PM
Probably a good idea to cover setting up:

...They should be toe'd in about 10-15 degees (no more). The slot radiators should be on the "outside".

When this is done correctly the system will reveal precise stereo imaging and front to back depth. ...



Ian had asked me if removing the 4343 nameplates made any difference in the UHF sound. It does! I hear more from the 2405 slot and I'm sure the patten is also improved by getting the nameplate out of the way. I'm going to drastically shorten the nameplates and mount them in the center to allow all the UHF to come out uninterupted.
Though Ian had mentioned placing the 2405s on the outside of the cabinets to me before, it wasn't until today that I went down and switched my 4343s, placing the slots at the outside position of the speakers.
I had a listen and I was impressed! The improvement was not subtle! Not only did the placement of the instruments become more clearly defined, but I heard top detail that I hadn't noticed quite the same way before...and this is with music I play regularly and am very familiar with. Though it seems counter-intuitive, I feel Ian was right when he explained how those slots need to be on the outside to blend with the other drivers correctly.
Thanks Ian, again, for your insight.
I wonder if JBL ever explained that, or any of what we are learning about setting up and tweaking our 434X speakers. ?

Tom

Ian Mackenzie
10-23-2005, 10:02 PM
Ian had asked me if removing the 4343 nameplates made any difference in the UHF sound. It does! I hear more from the 2405 slot and I'm sure the patten is also improved by getting the nameplate out of the way. I'm going to drastically shorten the nameplates and mount them in the center to allow all the UHF to come out uninterupted.
Though Ian had mentioned placing the 2405s on the outside of the cabinets to me before, it wasn't until today that I went down and switched my 4343s, placing the slots at the outside position of the speakers.
I had a listen and I was impressed! The improvement was not subtle! Not only did the placement of the instruments become more clearly defined, but I heard top detail that I hadn't noticed quite the same way before...and this is with music I play regularly and am very familiar with. Though it seems counter-intuitive, I feel Ian was right when he explained how those slots need to be on the outside to blend with the other drivers correctly.
Thanks Ian, again, for your insight.
I wonder if JBL ever explained that, or any of what we are learning about setting up and tweaking our 434X speakers. ?

Tom

Tom,

Perhaps JBL should issue a 4343 Manual!

Rolf
10-23-2005, 10:14 PM
Though Ian had mentioned placing the 2405s on the outside of the cabinets to me before, it wasn't until today that I went down and switched my 4343s, placing the slots at the outside position of the speakers.
I had a listen and I was impressed! The improvement was not subtle! Not only did the placement of the instruments become more clearly defined, but I heard top detail that I hadn't noticed quite the same way before...and this is with music I play regularly and am very familiar with.
Tom

Hi folks.

I did exactly the same thing as Tom yesterday, and agree that there was a great difference! In all the years I have had large studio monitors I have always placed them with the 2405's on the inside, as I have been thinking having them on the outside would make a lot more unwanted reflections from walls and other stuff in the living room. I was wrong! .. Or do they need reflections to sound better?...Naaa?

Regarding the 10 to 15 degrees, I have always had mine i 12.5 with the listening position a little longer away than the distance between the speakers.

Yesterday I also (WITH MY EARS) adjusted the L-Pads, and the sound is no much more focused. The singer/instuments are now in the same position...not "lurking around" as Ian talked about. I will however use an RTA and "see" how my ears are.

Rolf

B&KMan
10-23-2005, 10:31 PM
Ian had asked me if removing the 4343 nameplates made any difference in the UHF sound. It does! I hear more from the 2405 slot and I'm sure the patten is also improved by getting the nameplate out of the way. I'm going to drastically shorten the nameplates and mount them in the center to allow all the UHF to come out uninterupted.
Though Ian had mentioned placing the 2405s on the outside of the cabinets to me before, it wasn't until today that I went down and switched my 4343s, placing the slots at the outside position of the speakers.
I had a listen and I was impressed! The improvement was not subtle! Not only did the placement of the instruments become more clearly defined, but I heard top detail that I hadn't noticed quite the same way before...and this is with music I play regularly and am very familiar with. Though it seems counter-intuitive, I feel Ian was right when he explained how those slots need to be on the outside to blend with the other drivers correctly.
Thanks Ian, again, for your insight.
I wonder if JBL ever explained that, or any of what we are learning about setting up and tweaking our 434X speakers. ?

Tom

see instruction 4344 mkII too

page 8 " position" (see pict)


:cheers

Ian Mackenzie
10-23-2005, 11:56 PM
Hi folks.

I did exactly the same thing as Tom yesterday, and agree that there was a great difference! In all the years I have had large studio monitors I have always placed them with the 2405's on the inside, as I have been thinking having them on the outside would make a lot more unwanted reflections from walls and other stuff in the living room. I was wrong! .. Or do they need reflections to sound better?...Naaa?

Regarding the 10 to 15 degrees, I have always had mine i 12.5 with the listening position a little longer away than the distance between the speakers.

Yesterday I also (WITH MY EARS) adjusted the L-Pads, and the sound is no much more focused. The singer/instuments are now in the same position...not "lurking around" as Ian talked about. I will however use an RTA and "see" how my ears are.

Rolf

Rolf,

Glad to hear about the improvements..enjoy.

Perhaps this step should be the 1st step before any updates!

Alas who ever reads manuals.

regards

Ian

Just think this improvement didn't cost you a cent.

Rolf
10-24-2005, 02:47 AM
Alas who ever reads manuals.

regards

Ian

Just think this improvement didn't cost you a cent.

Hi Ian.

In the manuals delivered with the speakers I have had over the years there have NEVER been a word of placement. ...... Anyway, I can't remember any, and I do read manuals....http://audioheritage.org/vbulletin/images/icons/icon7.gif

Rolf

Ian Mackenzie
10-24-2005, 06:45 AM
Hi Ian.

In the manuals delivered with the speakers I have had over the years there have NEVER been a word of placement. ...... Anyway, I can't remember any, and I do read manuals....http://audioheritage.org/vbulletin/images/icons/icon7.gif

Rolf

I think we should write our own manual.

Ian

Rolf
10-24-2005, 09:27 AM
Be nice and people is nice to you.

Rolf,
I think that quote rightfully belongs to another member..http://audioheritage.org/vbulletin/images/smilies/scratchchin.gif

Now let me see who that could be ........Steve G http://audioheritage.org/vbulletin/images/smilies/biggrin.gif

......You should never steal what does not belong to youhttp://audioheritage.org/vbulletin/images/smilies/rotfl.gif

Sorry all. I did not know anybody was using it. I made up another one, hope nobody uses that.

Rolf

Ian Mackenzie
10-24-2005, 02:40 PM
Its was an in - joke.

Us the serach function and you'll see why

Ian

Rolf
10-24-2005, 03:13 PM
Its was an in - joke.

Us the serach function and you'll see why

Ian

Ok, search for what???

Rolf

Rolf
10-25-2005, 07:53 AM
Hi folks.

So, I have finally used an RTA on my 4343B's after Ian's instructions.

As I said earlier I adjusted the speakers by listening. This is how the L-Pads where with my ears: UHF: -2, HF: -2, MF: -1. Believe it or not, the only change after the RTA was adjusting HF from -2 to -3 on the L-Pads. I also had to lover the gain a little bit on the electronic crossover on the left channel, and I believe this is due to furniture in our livingroom.

How does this look comparing to your settings?? Please let me know!!!!!!!!!

Thanks to Ian and everybody else (the list is to long to thank everybody by name) who got me going with this. Now the sound stage is crystal clear, and I believe the need for an eq is gone. I recommend everybody with large size monitors to try this.

I wonder what will be the next issue.....

Rolf

Ian Mackenzie
10-25-2005, 01:43 PM
Great news.:applaud:

Happy listening


Ian

Rolf
10-25-2005, 02:28 PM
Great news.:applaud:

Happy listening


Ian

Thanks Ian. I am enjoying? it. How do you compare the settings of the L-Pads in your experiance?

Rolf

Ian Mackenzie
10-25-2005, 04:29 PM
Thanks Ian. I am enjoying? it. How do you compare the settings of the L-Pads in your experiance?

Rolf

Rolf,

My understanding is you have a stock JBL 4343 system.

My reference system is a JBL 4345. The 4345 has identifcal drivers and crossover network to the 4344 except the woofer. The 4344 crossover (3145) is different to the 4343 crossover (3143) and therefore the calibration is different. My L Pads are in "O" position.

In anycase if you have measured with your RTA the levels of the drivers to be flat then that is what matters and the subjective result will be obvious as you will forget about the speaker and start enjoying the music!

Ian

Rolf
10-25-2005, 05:21 PM
Rolf,

My understanding is you have a stock JBL 4343 system.

Yes, the 4343B. 2235H, 2121H, 2420 (alnico) and 2405 (alnico)




In anycase if you have measured with your RTA the levels of the drivers to be flat then that is what matters and the subjective result will be obvious as you will forget about the speaker and start enjoying the music!

Ian

Jippiaoitayey!!!! I DO, MORE THAN EVER! (And I am over 50)

Regards

Rolf

Ian Mackenzie
11-01-2005, 05:23 AM
For those interested in tackling some of the upgrades here are images taken of the project in development.

The origins of the signal driving the loudspeaker start long before the passive crossover.

We found during the course of the project development that the active crossover was a significant contributor of tonal accuracy, dynamics and resolving power of the loudspeaker system.

A new active crossover was designed and tuned to the application of biamping the 4343-4344-4345.

We also found that the capacitor coupling the (52 uf) midrange in the 4343 passive crossover had a direct impact on the midrange and hi frequency performance.

After various trials it was also determined that upgrading the drivers and the passive crossover to the 4344 specifications for biamping provided the maximum performance potential from the loudspeaker system.

An external passive crossover using audiophile grade components was build and tested using the Giskard equivalent 3145 crossover design.

Other refinements including the use of high quality terminations played a significant part in attaining the maximum resolution of the loudspeaker system.

Below are some images of the project reference components . A protective film covers the front panel of the passive crossover for shipping.

This is a diy project, not a commercial product and it was built by hand.

No doubt a better finish could have been arranged with a CNC lathe and other production tools, but would not have been half as much fun!

I would like to thank Ed for the opportunity to be involved in his project and for being so patient. This project was Ed's idea, its been a great pleasure working with you Ed...enjoy. I would also like to thank Giskard for his technical input and also Don for being able to share this on the Lansing Heritage Forums.

Ian

porschedpm
11-02-2005, 08:32 AM
I'm thinking the photos are arranged as follows (top to bottom):


Photo 1- Active crossover-innards
Photo 2- Active crossover-back panel
Photo 3- Passive crossover-front panel
Photo 4- Passive crossover-rear panel showing 8 pole Speakon connector
Photo 5- Baffle modified to 4344 specs

I'm continually amazed at the level of expertise demonstrated by Ian and a select few of the other members that make up brain trust here on the LH Forum. Thanks for inspiring the rest of us.

Ian Mackenzie
11-02-2005, 12:24 PM
I'm thinking the photos are arranged as follows (top to bottom):


Photo 1- Active crossover-innards
Photo 2- Active crossover-back panel
Photo 3- Passive crossover-front panel
Photo 4- Passive crossover-rear panel showing 8 pole Speakon connector
Photo 5- Baffle modified to 4344 specs

I'm continually amazed at the level of expertise demonstrated by Ian and a select few of the other members that make up brain trust here on the LH Forum. Thanks for inspiring the rest of us.

Thanks Ed,

Please note these are snap shots.

I need to label the active crossover front and rear panels.

Ian

sa660
11-03-2005, 02:01 AM
Ian,

Very good work,
I am always wondering about the recommendation for low frequency enclosure and the need to rigidify the cabinet.
For example could we extend the bottom wall of the mid cabinet to link with the side wall and back wall. This will increase the rigidity of the box and because of the asymetric position will help reducing the vibration of the resonance zone for the wall cabinet. Other means using 2x2" beans internaly will help.
Looking iniside the 4435 I beleive JBL did a lot of work on improving the rigidity and the energy from both 2234 is very well absord.

Ian Mackenzie
11-03-2005, 04:40 AM
Ian,

Very good work,
I am always wondering about the recommendation for low frequency enclosure and the need to rigidify the cabinet.
For example could we extend the bottom wall of the mid cabinet to link with the side wall and back wall. This will increase the rigidity of the box and because of the asymetric position will help reducing the vibration of the resonance zone for the wall cabinet. Other means using 2x2" beans internaly will help.
Looking iniside the 4435 I beleive JBL did a lot of work on improving the rigidity and the energy from both 2234 is very well absord.

I will post some images of the internal bracing of the 4343 in day or so.

One point to remember is that as a result of isolation of the mid and low frequency transducers in their respective chambers, the control of panel resonances and internal damping can tailored to meet the respective requirements.

As a result, the approach taken in a design such as the multi 4 way monitor can and would be different to a 2 way system such as the 4430/4435 where the enclosure is no doubt treated to control the bass and a large portion of the mid band frequencies.

Ian

Ian Mackenzie
11-06-2005, 04:47 AM
Positioning

Today I re arrnaged my system to arrive at a configuration to has less architectual constraints like doorways and windows.

The set up is now more like the graphic in the 4344Mk11 OM.

Prior to this I had to allow for a glass window opening b/n the louspeakers which restricted the distance b/n the loudspeakers. I now have what more closely resembles equi-distant positioning while my listening postion is further out from the rear wall.

The improvements are quite noticable.

Ian

Robh3606
11-06-2005, 08:07 PM
Hello Ian

I like that positioning guide. My second system is set up along those lines with some space off the rear wall and side walls. When you get the spacing close too or at that magic triangle it really is amazing what a difference in can make. I am a little close to mine set-up that way but it sure sounds good.
Rob:)

sfellini
11-07-2005, 08:19 AM
Hi -

I can't find this manual on either the JBL
support site or the Tech Ref section of this
forum. Could someone post it?

Thanks,
Steve.

Lancer
11-07-2005, 08:50 AM
http://www.harman-japan.co.jp/support/manual/4344Mk2.pdf

Ian Mackenzie
11-08-2005, 12:52 AM
Attached a diagram from the English version of the 4344Mk11 manual:

Ian Mackenzie
11-08-2005, 01:31 AM
Here are expanded details of the 4343- 4344 Project Upgrade External Hi End Crossover Network.

The original theme was a high quality passive crossover for use with the JBL 4344 components.

What evolved from our objectives during the design phase was a crossover network that would be external to the 4344 enclosure, bypass all existing passive crossovers and L Pads and wiring, and use the original equivalent 3145 crossover schematic designed by Giskard.

The practical realisation of the design is a pair aluminium cabinets that house the passive filters and a system of terminations and wiring that allow routing of both low and high pass biamped speaker signals via a customised cable to the 4344 enclosure. This approach will ensure the passive filters are isolated from internal enclosure vibrations while also providing phase continuity of the four individual signals from the crossover filters direct to the 4344 drivers.

The enclosures are 9.5 kg each, made from 3 mm aluminium and milled 25mm square aluminium stock. Auricaps and Mills resisters are used in all signal path locations. Pure copper terminations and Welbourne Teflon cable is used throughout. The binding posts are premium grade by Cardas and the 8 pole connector is a heavy duty Speakon. Provision is made for fixed resister values to replace the L pads once the system has been installed and calibrated.

A customised front panel was arranged to allow precise adjustment of the L pads during set-up and installation.

It looks deceptively simple, however there is a lot of fine detail and a reasonable degree of difficulty in the implementation.

In a week or two we will show more details of the installation and set-up.

Ian

Ian Mackenzie
11-08-2005, 01:48 AM
Here are some images of the 4343 internal construction.

All images courtesy of Subwoofer.

Ian

saeman
12-01-2005, 02:43 PM
Hello Ian: How's life downunder??? "Talk's Cheap And Whiskey Costs Money". I'm finally getting back to my 4344 project. Thought I'd pop you a few pics of the first cabinet - under construction but assembled dry for fit-up. The baffle layout was altered from JBL original to move the woofer off the center line of the cabinet as recommended by Giskard. I included the recessed area in the rear of the cabinet for mounting the x-over related components (external to the cabinet interior). Giskard commented that the area I provided was a bit generous, but not knowing the size required for the finished electronics prompted me to leave it a bit large (I can keep an emergency pint of Jack and all of my spare money in there). I've been fortunate to locate all of the proper components and will press on to completion. Here's a few pics. Thanks for your continued input on my project. Rick

saeman
12-01-2005, 02:47 PM
add'l pics

Mr. Widget
12-01-2005, 03:06 PM
Very nice craftsmanship as always, Rick. I would like to suggest you use KD lumber for your braces though. MDF and particle board are just not structural. I do think you can hear the difference. I have been using braces made out of 1.5" thick birch ply lately, but have also had good results with both KD Fir and domestic hardwoods.


Widget

saeman
12-01-2005, 03:13 PM
Hi Wig: Thanx for chiming in. I cut most of the braces this morning and will start fitting them in tonight. They are all 1 1/2" x 2 1/2" KD Douglas Fir. Never thought about using thick plywood on edge for braces - good idea. Where are you getting 1 1/2" thick birch plywood ??? Rick

Robh3606
12-01-2005, 03:33 PM
"Where are you getting 1 1/2" thick birch plywood ??? Rick "

Glue and screw 2x 3/4 works like a charm.

Rob:)

Mr. Widget
12-01-2005, 04:01 PM
I cut 4" strips from my waste and glue and clamp them... the next day I trim them to 1.5" X 3.5". It works quite well, and uses up the scraps. Sometimes I make it from fresh stock. The cost per cu. in. is about the same as KD Fir in my part of the world.

I brought it up, because in one of your photos, it looked like you were using some 1" part board. I guess I misinterpreted the image.


Widget

saeman
12-01-2005, 05:13 PM
.I brought it up, because in one of your photos, it looked like you were using some 1" part board. I guess I misinterpreted the image.


Widget

No, you're right - 1" P.B. - my mainstay, along with good 3/4" Baltic Birch and proper bracing. I HATE, no I DEPLORE, no I DESPISE MDF for my cabinet making chores. It makes a cloud of dust that gets into every orifice of your body, doesn't glue well and won't hold a screw or glued dowel pin on it's best day. I have used it for cabinet backs and screwed thru to the braces from the outside - OK, but the screws show and I like the clean appearance of no screws. I know this is contrary to the beliefs of many out there BUT are these people just repeating the same thing they hear from others or have they "Walked The Walk" as the saying goes. Proper bracing is the big issue for me - hell, maybe I'll switch to cardboard with some extra bracing.
:banghead: :banghead:

Mr. Widget
12-01-2005, 05:26 PM
I HATE, no I DEPLORE, no I DESPISE MDF for my cabinet making chores. It makes a cloud of dust that gets into every orifice of your body, doesn't glue well and won't hold a screw or glued dowel pin on it's best day.I agree, I agree, I agree... unfortunately it actually sounds better than particle board or solid lumber. The two hard faces with the dust core make a self damping material that is relatively inexpensive and coincidentally about the best material going for speaker boxes.

As for assembly, I use a narrow crown stapler... fast and secure... don't screw up though, the joint will not come apart. :(

I wear one of these, with a half face mask... I've used it for years while painting, and it keeps the handkerchief clean it you know what I mean. ;)


Widget

Robh3606
12-01-2005, 05:47 PM
Hey Rick

Those are nice looking cabinets!! Bet they weigh a ton! You have your drivers all lined up???

Rob:)

Ian Mackenzie
12-02-2005, 12:04 AM
Rick,

Any thread like this without pics is worthless.

Nice work.

I suggest you follow the JBL designations for tactical bracing per earlier drawings. Also there is are two front to rear braces that skirt the dog box to the rear panel. They make is big different to the rigidity of the front panel.

Ian



Hello Ian: How's life downunder??? "Talk's Cheap And Whiskey Costs Money". I'm finally getting back to my 4344 project. Thought I'd pop you a few pics of the first cabinet - under construction but assembled dry for fit-up. The baffle layout was altered from JBL original to move the woofer off the center line of the cabinet as recommended by Giskard. I included the recessed area in the rear of the cabinet for mounting the x-over related components (external to the cabinet interior). Giskard commented that the area I provided was a bit generous, but not knowing the size required for the finished electronics prompted me to leave it a bit large (I can keep an emergency pint of Jack and all of my spare money in there). I've been fortunate to locate all of the proper components and will press on to completion. Here's a few pics. Thanks for your continued input on my project. Rick

4313B
12-02-2005, 05:31 AM
No, you're right - 1" P.B. - my mainstay, along with good 3/4" Baltic Birch and proper bracing. I HATE, no I DEPLORE, no I DESPISE MDF for my cabinet making chores. It makes a cloud of dust that gets into every orifice of your body, doesn't glue well and won't hold a screw or glued dowel pin on it's best day. I have used it for cabinet backs and screwed thru to the braces from the outside - OK, but the screws show and I like the clean appearance of no screws. I know this is contrary to the beliefs of many out there BUT are these people just repeating the same thing they hear from others or have they "Walked The Walk" as the saying goes. Proper bracing is the big issue for me - hell, maybe I'll switch to cardboard with some extra bracing.
:banghead: :banghead:Alrighty then! :p

Yeah... I've walked the walk and killed a few trees in my time. I used Novaply for many, many years but switched to MDF in the late 90's. The dust is deplorable and I'm always cleaning filters for my shop-vacs. Bracing has always consisted of select pine.

They do look nice as usual Rick.

saeman
12-02-2005, 10:02 AM
Ian - Giskard - Wig: I'm planning on starting to install braces tonight but after your comments I thought I'd bounce my ideas off you guys. Since my 4344 cabinet is a deviation from factory and also from Ian's plans, the bracing has to be different in my view. I pushed the mid-base box clear to the right against the cabinet side. This was to allow installation of the mid driver, thru the woofer hole, without providing a removable rear access panel. The side of the mid-base box will be glued/screwed to the cabinet side and eliminate a side brace at that point. My rear panel is in three sections and the dividers are 1" x 4" P.B. They essentially act as left to right back braces across the back panel. They are dado/glued into the cabinet sides. All other braces shown on my pic are 1 1/2" x 2 1/2" doug fir. I also provided a lateral brace across the baffle just above the woofer cutout. The line shown in red is a possible brace befween the mid-base box and cabinet back. Thought I'd assemble the cabinet and then decide if that brace was needed. Take a look at my attached pic and comment if you will. Thanx - Rick

Mr. Widget
12-02-2005, 11:17 AM
I would definitely add the red brace(s) too. I have found tying the middle of the baffle to the back and the middle of the sides to each other really stiffens up the box and the bass response. Having braces crossing the central cavity of the box can make it difficult to install networks etc., but when possible I try to do it... it just sounds better.


Widget

Robh3606
12-02-2005, 11:40 AM
Your braces look good. In my boxes I use pine 2X3 on edge and wraped them round the box on 3 sides and had a baffle stiffener across the front as well. Have 1x2 as well. Did them in odd intervals like your to try to break the panels up into different sizes. Also have the front and back panels connected through the dog house.

Rob:)

Ian Mackenzie
12-02-2005, 01:32 PM
Looks good

Ian

Ian Mackenzie
12-06-2005, 03:47 AM
I have been refining the previously mentioned active crossover.

The unit it such that it would appear to be the final arbitrator of all post signal elements

I have attempted to a/c couple the balanced outputs for safety. This will require some research and evaluation as prior art passive devices appear to loose the elusive being there boogie factor.

I have ordered some Black Gate N / Nx series for trial in Super E configutation and charge coupled configuration.

saeman
12-06-2005, 02:43 PM
Hello Ian: I'm at a stand still on my first 4344 cabinet. I need to know the port duct tube length JBL used on their 4344's. I've combed thru your thread and cannot find a number on length. I have 4" diameter. Do you know or is there someone out there who owns 4344's and can take a measurement. Thanx - Rick

Ian Mackenzie
12-06-2005, 03:18 PM
Off hand I don't know...Lancer might..!

I spent months trying to find out the tuning of the 4345. In the end I sent a request to JBL, Greg Timbers wrote to me the next day...:) It should be noted JBL tuned some of their monitors empirically.

I am sure a few members to come up with some suggestions..........

We really need to know your net enclosure volume to provide an accurate model of the tuning using the driver T/L parameters and if you plan to use one or two ports and the inside diameter. Please confirm.

Try a search for 2235 tunings in the technical forums. A couple of hertz either side of the idealised tuning will give a satisfactory result....according to taste and your room acoustic.

Go here, Giskard covers the subject perfectly..as always.

http://www.audioheritage.org/vbulletin/showthread.php?t=2743&highlight=2235+tuning

Regards the port length, tuned to 30 hertz in 5 cu ft3 requires two 4 inch ports 10.3 inches long according to BassBox Software, or one 4 inch port 3.5 inches long with normal fill 1 inch fibrelgass on all sides except front baffle QL = 10 F3 = 31.4. Bassbox as a rule is quite accurate at determining these data, but its only as good as the assumptions made in the simulation.


If you are tehncially inclined......the scientific approach

Technically, QL is quality factor for expressing box losses (leaks, panel flexure, cone leakage) and is an unknown factor effecting bass response in a model simulation (and in reality) .

In a very rigid box with no leaks you can expect QL= 10 or more and this will tend to cause a rise the response 1/2 a db in the tuning region over a nominal QL=7. A QL = 3 is a lossy box and will cause a drop on the response at tuning.

Also the driver QTS (or total Q = electrical Qt = mechanical QM) is effected by series Dc resistance of the cables, crossover network and amplifer output impedance. If this is large (0.5> ohms) it will effect the bass quality at tuning and transient performance of the system will suffer. For example modifying the QTS by 10%+ will cause a 0.8 db rise at 50 hertz (ripple) .

These effects can be adjusted to a degree by either adjusting the tuning slightly (+-2 hertz) or the net volume (+-10 %) although siginificant changes in QL or QTS should be avoided.


Practically speaking .........

I suggest you start out with a longer length port and test the tuning wth a low level sine wave signal and monitor the physical movement of the cone which will be at a minimum at resonance.

The actual impediance is not a reliable means of determining tuning at resonance as the curve is almost flat and the lowest point on the curve is not necessarily the point of resonance(due to reactance of the driver motor).

Let us know how you go...and have fun.

Ian

Ian Mackenzie
12-09-2005, 04:37 PM
Another thought for those intending to biamp.

http://www.audioheritage.org/vbulletin/showpost.php?p=81006&postcount=181

Ian Mackenzie
12-10-2005, 09:38 PM
From the Kitchen table

Remember the old rule for turning off your power amp and preamp.

On first and off last.

The same applies to other devices in the signal chain such as an active crossover or graphic equaliser. Some commercial units have a built in turn on delay and mute on turn off.

I built the unit below to be installed in the custom active crossover for the JBL 4344/4345. It operates from the unregulated supply and shorts the balanced outputs for a 4 seconds and instantly after turn off thus avoiding any start up or turn off transients.

saeman
12-12-2005, 09:45 PM
Hello Ian: Do you have Christmas in Australia in December or in June - since you're on the other side of the world. Yeh, Yeh - everyone like a little ass nobody likes a smart ass, right. I'd trade weather with you right now. Anyway - I'm getting closer on the 4344 project and thought I'd post you a couple of pics of the effort. I've got one cabinet built; without skin right now as the veneer is still a week out. I brought it into the house temporarily to make room to build the second cabinet - and I couldn't resist putting the components in it to have a look. 2235H, 2122H, 2425J/2307/2308 and 2405. Since my rosewood 4350B's ran away from home I'm going to do this pair in rosewood so I can have some in the house. I'll get you some more pics when the cabinet is finished. Happy holidays - Rick

Ian Mackenzie
12-12-2005, 09:51 PM
Nice.

Ian

4313B
12-13-2005, 05:42 AM
I'm getting closer on the 4344 project and thought I'd post you a couple of pics of the effort. I've got one cabinet built; without skin right now as the veneer is still a week out. I brought it into the house temporarily to make room to build the second cabinet - and I couldn't resist putting the components in it to have a look. 2235H, 2122H, 2425J/2307/2308 and 2405.Looks much better than the stock 4344. Very nice! :yes:

yggdrasil
12-13-2005, 06:00 AM
Looking goooood!

Robh3606
12-13-2005, 08:07 AM
Those look sweet!!! Wait till you power them up. They will sound even better than they look.

Rob:)

saeman
12-13-2005, 12:28 PM
Thanx Rob - Getting the veneer on them will make a real difference but the bigger problem now is the lack of continuity between the rear terminals and the components. Unless I can program the incoming electrons to jump thru air to the right driver I've got a problem. I now need to get busy on the cross-overs. For now they'll have to look better than they sound.

Rick http://audioheritage.org/vbulletin/images/smilies/bouncy.gif

Ian Mackenzie
12-14-2005, 10:28 PM
What crossover configuration have you decided on?:blink:

Sorry I shoud never ask such difficult questions:dont-know

Ian

Tom Loizeaux
12-15-2005, 07:16 AM
What crossover configuration have you decided on?...
Ian

You've done a great job with those cabinets! And yes, we're all waiting to see what crossovers you use!
I do know of a pair of 4343 stock crossovers, but with the 2122 mid drivers you probably need slightly differant slopes. I think, if I were in your position, I'd bi-amp these and try Ian's custom passives (tweaked for your drivers).

Anyway, good work...keep us posted!

Tom

Ian Mackenzie
12-24-2005, 11:12 AM
Looks much better than the stock 4344. Very nice! :yes:

Well when you are done with the crossovers he is in for a real treat.

I listened to the Carol's last night on TV and it would be difficult to imagine anying more impressive than a 4344 using the Giskard's crossover design.....it just didn't sound like loudspeaker at all.

There is discussion elsewhere on the virtues of overly expensive Westlakes in reference to the 4343.

If you take your 4343's to the next level (as discussed in these pages) you can be content that without spending a real lot of money they will give anything else a serious run for their money....and you will have the true JBL sound!

On that note I am inspired by Rick's handy work and I plan to build a 4344 in 2006 using the Giskard crossover and enclosures using a special acoustic grade ply with lead laminate to ensure minimal sound transmission.

Ian

Ian Mackenzie
12-24-2005, 11:41 AM
I am sure once you are making them you will enjoy it!

Ian Mackenzie
12-29-2005, 04:45 AM
Update:

http://www.audioheritage.org/vbulletin/showthread.php?t=8477&page=1&pp=15

Incidentally,

Something most of you propably have skipped over, the inception of the 4343-4344 thread was of Porschedman, (Ed) who asked me over 12 month ago to build some new crossovers for his 4343's that he had updated to 4344 driver specs.

Ed has yet to install the new crossovers and write an detailed review which I would expect sometime in Feb -April 2006 pending Ed's schedule.

The reason I bring this up is the "project" is still in a state of flux and if with the arrival of the now new "DIY Forum everything gets chopped up and the whole continuity of the project will be lost.

I should also point out that prior to publication of the 4343 -4344 upgrade project there was such contentious resistance to the idea by Super Moderator Robert Hamel that the project was nearly dropped.

Robert, fearing members might not hear the difference would therefore have post-project concerns over there being a lack of value for money for the effort and the outlay involved. This reaction served and prompted me into investigating and proving the updates even more rigorously.

What eventuated was quite revealing.

My approach is simple. Take nothing for granted and assume nothing when it comes to this business..

Old ears and attitudes are deaf ears in this business.

But if you are the cautious type you may want to wait for Ed's reviews and then make up your own mind.

Collectively however, if you follow and read carefully all the steps in the 4343 upgrade stages common sense prevails and there is justification and satisfaction to behold by every 4343 owner. Even the most passive changes like enclosure height adjustments and positioning can be the difference b/ n love and hate with these systems.

Change is often good and refreshes our sensory perceptions. Even Ed was surprised after some hounding by me at the overall improvement reverting back to full 4343 passive crossover mode made with his Passlabs X Series 250 power amplifier over using the Ashly active crossover in bi amp mode. The point being if the expertise and reasoning behind this was not pointed out in the way it was Ed would never have made the change and been the non the wiser. This is a key behaviour in attaining the ultimate in audio sound reproduction. Don't let sticks in the mud stop you from progressing, walk over them if you have to.

It is interesting to note that JBL also resisted the innovation and introduction of the L250 designed by Greg Timbers for some time and it was then latter upgraded to the 250Ti and remains one of the best JBL systems of all time.

Ian Mackenzie
12-31-2005, 05:41 PM
I have been getting a string of pm's nagging me about that discrete active 4343-4344-4345 active crossover and that the details are scattered all over the place.

Its taken a while (over 12 months) to perfect it, numerous iterations, adjustments and component choices apart from getting all the bugs out hence the odd post here and there to let you know its still alive.

I am not proposing to publish a how to article or the final design.

If you think you are competent enough to design and make it please go to the Mox thread on diyaudio.com and have a go at it from scratch otherwise all genuinely interested parties please pm me (again with your email address) so I can put you on a mailing list.

best regards

Ian

porschedpm
03-20-2006, 04:07 AM
13975
13974
13973

porschedpm
03-20-2006, 04:37 AM
Remove LF and MF drivers.
Remove Upper Baffle. Disconnect HF and UHF drivers. Pull MF wires out of MF box.
Label all wires. Recommend taping off or placing shrink tubing over these abandoned wire ends to avoid any future mishaps. Coil up the old wires and secure with a tie wrap13976

Prepare your 5-3/8" x 6.5" wood or plexiglass panels to replace the rear input teminal plates by drilling a 1-3/16 hole for the male Speakon connector and pilot holes for the screws. Alternatively you could leave the rear input terminal plate in place and drill a 1-3/16 hole in the speaker cabinet for the Speakon connector. I opted to replace the plate so that the speaker could be returned to stock condition and to retain the value of the speaker.
Remove rear input terminal plate. Route it out of the way and in a place that will be rattle free. I wedged it into the upper left hand corner of the speaker and covered it with fiberglass. 13977


Install your wood or plexiglass panels which replace the rear input terminal plates. If your panel is less than 3/8 thick, you can re-use the original bolts. Regardless if you use the original bolts or not, you will need new nuts as the nuts on the original rear input terminal plate were pressed into the fiberboard and cannot be removed. 13978

Install front-to-rear brace. My brace ties the top of the rear center 1x4 upright brace to the front baffle. Where it ties into the front baffle it is offset to the left approximately 1 from center to provide clearance for the lower center baffle bolt and avoid interfering with the stock L-Pads. I made very sure before gluing and screwing that this bracing would not interfere with the L-pads. Im sure there are other and maybe better ways to provide additional bracing in the 4343 cabinet so I wont go into more detail here other than I did cover the new braces in fiberglass. 13979
13980

porschedpm
03-20-2006, 04:56 AM
Install Speakon connector in your wood or plexiglass panel.13981
13983
13985

Route MF leads into the MF Box. Seal the hole.
Reinstall drivers.
Connect crossovers.13984
13982

Balance Drivers using the Ian Method outlined at : http://www.audioheritage.org/vbulletin/showpost.php?p=60625&postcount=7 (http://www.audioheritage.org/vbulletin/showpost.php?p=60625&postcount=7) Downloadable test tones can be found at:
· http://www.ronelmm.com/tones/ (http://www.ronelmm.com/tones/)
· http://www.nch.com.au/tonegen/#101

Play some music, and make sure all drivers are operating properly.

gerard
03-24-2006, 08:12 AM
Hello

Please forgive me but , where can I find the Giskard's crossover design drawing for the 4343 .

This thread is very nice but whre is the crossover design ? :blink:

Gerard

Ian Mackenzie
03-24-2006, 01:08 PM
The original schematic is below however the upgrade for the 4343 to the factory 4344 used the 3145 network. Since then the tapped inductors are NLA and Giskard/GT re designed the HF and UHF filters for an equivalent design and more recently a simplified "new equivalent".

These schematics have been posted so often elsewhere I didn't re post them earlier in the thread.

Here are some other links and aside from that you can also charge couple if you wish.

http://www.audioheritage.org/vbulletin/showpost.php?p=51638&postcount=169
http://www.audioheritage.org/vbulletin/showpost.php?p=51639&postcount=170
http://www.audioheritage.org/vbulletin/showpost.php?p=51684&postcount=173

gerard
03-25-2006, 01:46 AM
Thank's a lot Ian :applaud:

Now it's better to understand , the threads on 43xx are so large , you get lost sometimes .....

Gerard

Ian Mackenzie
03-28-2006, 07:15 AM
While Ed is waiting for the delivery of an active crossover I disgress to offer some commentary.

One of the themes that we are pushed in this upgrade series is that the sum of a number of key updates will lead to overall improvement in listening pleasure.

I recently had the opportunity to evaluate an improved compression driver and while it was obvious there were real improvements in transparency I also felt that the system had taken a step back as certain colourations had surfaced in the presentation.

By chance I also accepted the opportunity to trial a different AV Processor that uses a Shark processor. All my previous observations were based on a quality DVD player that had a built in decoder. The new processor is subjectively better and the above mentioned colourations have vanished.

This has also given rise to a final assessment of the active crossover before being shipped as my previous evaluations were based on assumptions using the original source. Things like component choices in key areas require careful consideration to ensure the signal path remains absolutely pure.

In order to do this and be absolutely certain of the results Ed will get I had to completely re build the passive crossovers to the exact specification that was delivered to Ed recently.

As you can appreciate nothing is left to chance with Hi End audio particularly when you have JBL loudspeakers!

Ian

porschedpm
05-03-2006, 04:34 AM
Below is a link to Greg Timbers' observations regarding the 4345 and some suggested improvements that could be made to the 4345's. Many of these suggestions could also be applied to the 4343/4344's.

http://www.audioheritage.org/vbulletin/showpost.php?p=110075&postcount=27

4313B
05-03-2006, 05:58 AM
Many of these suggestions could also be applied to the 4343/4344's.Definitely. We've gone over them quite a few times. Now that Greg has put them all down himself, I wonder if we will still have to continue to go over them. :p I notice after David took the time to write about the 4430... oh nevermind. :rotfl:

Ian Mackenzie
05-03-2006, 07:23 AM
Its the how, not how many.

Yes I agree you have been talking about charge - coupling for years now.....But how many have actually built their own.......

What is apparent is the reluctance of some members to modify these grand vintage monitors because of the difficulty as stated in the link above in making these modifications and that of not being able to re sell them in original vintage condition unless these changes are carefully implemented.

That is quite understandable.

The extent to which a particular owner decides to make these changes is entirely at their discretion. The might leave it for a while and then come and ask you about it because they are ready.

My understanding is the "How" as decribed in Ed's project offers minimal invasive impact of non reversable change while taking up many of the benefits of these modifications. (please refer to previous posts in this thread).

Unfortunately our "new" owners will not always be aware of these threads and the details of the modifications therin and what they mean.

This was another reason for opening the club thread. Its brings members together and enables a focal point of a micro forum community of owners. From there they can gather and share information efficiently while also communicating to the wider forum.

As the forums grow in size an complexity we all need to adopt smarter ways of managing our valuable information.

Perhap you can arrange for some of these updates to be copied as a pdr in a reference update area or a sticky?


Ian Mackenzie
Melbourne Australia

4313B
05-03-2006, 07:32 AM
On the subject of "minimal invasive impact of non reversable change while taking up many of the benefits of these modifications." Please realize I've already done several 250Ti's that are completely reversable and Bo and I have already discussed minimal impact to stock 4345's. I believe the subject of minimal impact to stock systems has been a fundamental theme I've mentioned pretty consistently over the last five years. The painful fact is, most people who would like 4345's will need to build them themselves.

As the forums grow in size an complexity we all need to adopt smarter ways of managing our valuable information.

Yes, I'm working on that. :)

Thanks Ian.

Ian Mackenzie
05-03-2006, 07:55 AM
I think you mis interpreted my meaning.

I many posts for example 4343 owners have concerns about making change. Some prefer to hang on to a bit of the past also.

We are feeling our way with 4345 owners..I see the bulk of these updated being applicable to 4343 owners wishing to go to the 4344 because of the size of the 4345.

Bo and I have also discussed about updating the current original 3145 original network in his 4345, parts sizes ect and skill of doing it. Do I put in a network ect, bypassing the switch etc.

That can be seen as a potential barrier to change.

And then putting it all down in a post for someone to follow ain't that easy.

Robh3606
05-03-2006, 08:17 AM
Hello Ian

Why don't you do a How To like Menu??? The basic crossover mods should not be done to the originals anyway. Those get removed or left in the box as is. The new networks can be done inside or out. The basic charge coupled topology is really quite simple with an explanation and example. The only open issue is the skill of the person doing the mods. Asside from soldering, and understanding a basic crossover schematic these skills should not be beyond most members. It may not be a bad idea to list the skill sets required for the modifications and recomendations to threads or other sites to build on these skills.

Rob:)

Ian Mackenzie
05-03-2006, 08:37 AM
Hmm.

I took me a long time to understand let along build my 1st network.:o:

But then again I am a slow learner......:p

I can see a benefit in people getting there feet wet though ;)

4313B
05-03-2006, 08:49 AM
Perhap you can arrange for some of these updates to be copied as a pdr in a reference update area or a sticky?Absolutely. However you want to put it all together. I had asked Greg to do the 4345 and 250Ti thing with the intent of putting it in the same format as David's article. While it's easier on the both of us that he simply posted it in the forum it will get buried if left alone so I will have to rectify that. I wasn't terribly specific in my intent. Besides, the personal post has considerably more impact. :D

Tom Loizeaux
05-03-2006, 09:10 AM
... I had asked Greg to do the 4345 and 250Ti thing with the intent of putting it in the same format as David's article... Besides, the personal post has considerably more impact. :D

Yes, and hearing about suggested mods from Greg makes some of us a little more comfortable with the idea of digging in to our factory crossovers.

Thanks Giskard for getting Greg to contribute that teriffic posting.

Tom

4313B
05-03-2006, 09:43 AM
Yes, and hearing about suggested mods from Greg makes some of us a little more comfortable with the idea.:yes: :thmbsup:

And that's understandable. JBL has put, what I consider to be, alot of time into me over the last 30 years. Greg is one of those people who has so graciously given his time over those years. Going forward I will no longer be championing this forum so this forum will have to get their input some other way. I would imagine Don, Greg and others will need to contribute more. However I think everyone should keep this post in mind with respect to Greg - http://audioheritage.org/vbulletin/showpost.php?p=109441

B&KMan
05-03-2006, 10:58 AM
Thanks Giskard for getting Greg to contribute that teriffic posting.
Tom

Oh yes!!

the first hand information is all the time better, especially from the first master ingeneer JBL... thanks Mr. Timber.

Many juice in few words, mmmmmmmmmmmmmm

:applaud: :applaud: :applaud:

Zilch
05-03-2006, 12:22 PM
As the forums grow in size an complexity we all need to adopt smarter ways of managing our valuable information.

Yes, I'm working on that. :)The many 4343/4344/4345 build/update/modification threads in these forums comprise a daunting challenge for anyone interested in actually doing anything, and the several attempts at organizing them to date don't seem to have helped much.

"Quick & Dirty Contents" has worked out well as a roadmap through my 4430-inspired project thread(s); it shows up in any searches for the specific subject matters covered, and, with highlights, then links to the specific positions in the threads where they are discussed.

Let me humbly suggest this as a workable approach to bringing order to chaos. Someone familiar with the material could put it together with just a few days' effort, and with continuing access, could build/update it over time....

http://audioheritage.org/vbulletin/showthread.php?t=9901

Ian Mackenzie
05-03-2006, 11:58 PM
Be my guest,

I really don't have time to be involved in any of this in the next few weeks.

Ian Mackenzie
05-30-2006, 05:51 AM
Speaking of upgrades something is coming over the Big Pond to the West Coast of the U.S.A.

When it arrives it will make a bigger (massive) improvement for one member at least than everything else that has been discussed on this topic to date.

Watch this thread for more details.

Ian

jandregg
06-04-2006, 03:59 PM
This is a little spread out but it allows trying different caps without cutting the leads.

JBLnsince1959
06-05-2006, 07:33 AM
jandregg

I could be wrong ( it's hard to see exactly in your picture) but are those mundorf caps?? if so which ones and how do they sound??

can you tell us a little more about your crossover.....

jandregg
06-05-2006, 01:51 PM
Nothing new there. They are Solen metalized film. There is a big difference in the 077 sound. Very clean and clear. I do not hear a big difference in the compression driver, but I am replacing bypassed metalized daystons in a copy of the 4343 crossover that already sound very good. Before I can say for sure I think I need to build one for the other side and hear it in stereo.


John

JBLnsince1959
06-05-2006, 02:05 PM
Hi John:

Thanks for the reply...interesting....

I know what you mean about being sure of a sound. Takes time. Let us know what you come up with.

it takes me awhile to tell if a new sound is better or just "different"

By the way..what part of Ga are you in, I have family in Gainsville.

rick

Ian Mackenzie
06-06-2006, 01:43 AM
On the sound thing I would like to point out that many components types do exhibit different tonality, sometimes subtle for audible variations. The differences can be expressed technically as distortions of one sort or another.

I have been conducting a lot of investigations into use of different brand parts and types of recent months and what is clear is that it may be worse, the same or different.

The key is to find parts that offer complimentry tonality that is pleasing to your ear.

Getting the right blend can be quite a chore but satisfying in the end.

Ian

jandregg
06-06-2006, 03:14 PM
Rick

I am 30 miles south of atlanta, gainsville is a bit north of atlanta. Probably an hour or so trip between the two. I grew up in KC and still have family there. Next time your in the area drop in for a listen. I am always glad to show off my jbls.

I hope to get the second crossover built this weekend. Then do some serious listening.

Cannot afford any really expensive caps, but will try mixing and bypassing on the charge coupled. I mixed some auricaps in with the daytons on my old bypassed crossover and found it made a huge difference. When people on this site first started talking about charge couple they were saying that bypass was not needed. In later post around the first of the year some ( Ian ) were reporting good results from bypassing in some instances. What a happly conundrum.

John

Ian Mackenzie
06-06-2006, 10:39 PM
It depends how far gone you already are..in other words if your amps are AAA with AAA prices spare no expense...so scale you outlay accordingly..its all relative.

porschedpm
07-16-2006, 03:35 PM
I’ve been invited by Ian Mackenzie to publish an outline of the upgrades that I’ve made to convert my 4343’s to 4344 spec. And give my impressions of the resulting sound. This 2 ½ year upgrade process has culminated with the recent addition of custom built active and passive crossovers built specifically for my application by Ian. A summary of these upgrades are as follows. For more description and detail of these upgrades you’ll want to drill back through the 4343-to-4344 Upgrade Discussion thread.

Upgrade 4343B drivers to 4344 spec.
1. Replace LF 2231H drivers with 2235H
2. Replace MF 2121H drivers with 2122H
3. Replace HF 2420 compression driver with 2425J.

Bi-Amp speakers:
1. Pass Labs 250w/ch Class A amp for LF drivers
2. Pass Labs 150w/ch Class A amp for MF-HF-UHF drivers
3. Ashly XR-1001 2-way active crossover

Upgrade stock passive crossovers:
1. Outboard crossovers custom built specifically for 4344 application by Ian Mackenzie.
2. Outboard crossover design completely bypasses the 4343’s Bi-Amp switch
3. Outboard crossover design completely bypasses the 4343’s L-Pads

Added internal Brace

Upgraded active crossover:
1. 2-way active crossover custom built specifically for 4344 application by Ian Mackenzie

Evaluation of upgrades.
1. When I upgraded from the 4343B to the 4344 drivers the changes were subtle. The low frequencies now seemed a little more detailed. The mids seemed to sound more natural and the highs seemed to be much more extended and natural (although I should add that some readers have said they prefer the aluminum diaphragm in the 2425H).

2. Bi-amping the speakers added quite a bit of detail and authority to the low end. I had issues though that I attributed to the Ashly active crossover (or possibly the internal Bi-Amp switch or a combination of the two). What I gained in detail and authority on the low end, I gave up in terms of transparency and fullness of the music from the mids on up. The music sounded somewhat thin and undynamic. It seemed like the music was veiled. I described the sound to be as if there was something in between me and the speaker. I could still hear the music but it just wasn’t alive. I went back to a single amp set-up to verify it was the Ashly crossover/bi-amp switch causing this. I eventually decided that bi-amping was still the way to go and so went back to the bi-amped set up and started looking for a better quality active crossover.

3. Adding in the custom built outboard passive crossovers, eliminating the internal bi-amp switch and L-pads, and adding the internal bracing was all done at the same time. While it would have been ideal to listen to the differences after each of these upgrades separately, it wasn’t practical to do so. But taken together, and probably due in most part to the new passive crossovers, they allowed the music to open up and be more full and transparent. The speakers sounded better than they ever had before. Even though there was still some slight veiling effect from the Ashly crossovers, it appeared to be minimized.

4. It’s been a little over a month since I upgraded the active crossover to the custom active crossover Ian built specifically for my application. See pictures below active crossover. What you don't see is that the power supply is oused in a complete differen box and is hidden behind the equipment cabinet. Adding in this active crossover was another quantum leap forward. The veiling caused by the Ashly switch was now completely gone. And there was huge increase in detail from top to bottom. There was an overall new transparency and fullness to the music. The low end had a huge increase in control and authority of the bass. The mid through highs were now so crystal clear that any imbalance between drivers immediately stood out. It took me several attempts to get the balance amongst the drivers correct but once I did, the music became jaw-dropping good. It was detailed and dynamic. In fact it became hard to stop listening because it made all the old music I’d heard hundreds of times before, fresh and exciting again. I found subtle nuances I hadn’t noticed before because the detail just wasn’t there before. I still am amazed at how good it sounds when I turn on the music after being away for awhile. It’s nothing short of awesome. The music is now full, dynamic and detailed.

It's taken over two years to get to this point but this latest upgrade has made the whole upgrade journey worth it. I can't over emphasize the importance using good quality crossovers. The quality of your crossovers should be at least equal to the quality of your other components. Really the easiest part was sourcing and installing the 4344 spec drivers. The most challenging part was upgrading the crossovers. You can use the stock 4343 crossover temporarily, but it was never designed for the 4344 drivers. And if you can find a 3145 network out there chances are it's time for it to be upgraded anyway. So invariably you'll be faced with having to custom make or if you have the time and expertise to do so. I had neither, so I was fortunate to have Ian custom make the crossovers for me. I asked Ian for his help because he understood the amps I was using and could match the quality of the crossover components to them. But there have been several LH threads written on building crossovers and there are several Forum members that have the ability to custom build networks. My deepest thanks go out to Ian for his patience, persistence and technical wizardry in building these phenomenal crossovers. It's hard for me to imagine how the music can sound any better. Although I have heard Ian's currently toying with the idea working on incorporating a small Pass DIY amp into an active crossover chassis to run the UHF-2405's. Sounds interesting.

Ian Mackenzie
07-16-2006, 05:23 PM
Ed,

Thanks for the thoroughly informative post.

Its nice to see a challenging project like this turn out the way it has.

I must say this would never have happened had it not been for Ed's passion, persistence and devotion that took this project to where it is today.

It was a lot of fun and I am so pleased we meet and worked on this project together.

Enjoy.

Ian

Ian Mackenzie
07-16-2006, 06:18 PM
Okay,

About the self powering of the 2405 it looks like Ed wants to go top shelf (again) so it might have to be one of these.

This particular amp is a mini class A power amp with some similarities to the amps Ed is already using in his system. Ideally, all amps in the mid and high registers should be of identical design/type.

Below are some old but timeless links to the above mentioned active crossover that has been the result of numerous improvements. There is a sister unit that is embedded permanently in my current system

http://www.passdiy.com/gallery/hi-lo-xover-p1.htm

The little amp also deserves some mention as it was reviewed some time ago now..excuse my enthusiasm at the time.

http://www.passdiy.com/gallery/alephx-p1.htm



Ian

JBLnsince1959
07-17-2006, 11:01 AM
porschedpm

Great post and congrads on your upgrade. Glad to hear it has gone well for you. I'm waiting to hear how the Highs are affected with the new little amp..

Ian...Fantastic job...You're a real asset to this forum more than you know. I know you were there for me last year when I had questions and I really appreciate it....way to go buddy..

Just to let you know, this is one of my favorite threads..while I don't have these speakers the principals can easily be applied to other speakers

thanks guys....

Steve Gonzales
07-17-2006, 01:26 PM
Thanks Porschedmp and Ian Mackenzie! :applaud:

boputnam
07-19-2006, 06:07 PM
The veiling caused by the Ashly switch was now completely gone.Doods...

First, thanks for the detailed postings and even more congrats for the 2-yr long exercise. That is devotion. You and Ian look to have done one hell of a job. I wish I had reason to travel to Reno...!!

The quote confuses me. I've "heard" that from but a few members here, and don't get it. Were you able to collect any measurements of the response, before and after? Could you post some plots? Also, you didn't post whether there is any EQ in the signal path, and if so what it is, and what corrections you might be imparting.

I ask because I just inserted a Bryston 10B in-place of the Ashly - but not for the reasons you did, nor with the results you got. I am trying to achieve what I understand is Greg Timbers' ideal active crossover application with a 4345 - use the active crossover in a biamp set-up to replicate the voltage drive of the original HPF (-12dB, 290Hz).

I have not yet Smaart'ed this - I am waiting Widget's visit this weekend for some A/B, and don't want to corrupt the current set-up before I go fully into the Bryston config - but what I did get (admittedly NOT properly EQ'd and therefore results/opinions are not relevant), is seemingly improved tonality, and better channel separation. I say not relevant because in my soundguy work, I typically am confronted with a system that sounds either muffled or bright, or "veiled" or boomy, and have found time-after-time that proper measurements of room response and adjustments for that response vastly improve the character of the sound, and the perception of the system (and audience response and appreciation!). This is experience based upon Smaart'ing dozens and dozens of systems, often when I felt there was either no hope, or it was already so good there was little improvement that could be made. Wrong on both accounts.

The "brightness" many attribute to Bryston, IMO, relates to EQ. Bryston may be more efficient in their reproduction of the HF part of the spectrum - therefore, systems not "aware" of that will certainly sound brighter.

I've got measurements before this switch, and soon will Smaart with Bryston and share those.

Ian Mackenzie
07-19-2006, 10:01 PM
Hi Bo,

Your post poses several questions so it may take several posts to reply.

Firstly,

The transparency is not related to amplitude response measurments but the E 2 E end distortion and other losses that are reduced with the active crossover and external crossover.

I was not able to discern any change in response from new or old crossovers (the voltage drives being almost identical)..calibration of the system is the Key.

We found the final L Pad setting more critical with the improved crossovers, I found about -1 db on the mid range and HF and UHF 0 postion using my net spl calibration method best with active using the ststem design 18 db slopes.

Hope this answers some of your questions, no Doubt Ed will add some comments.

regards

Ian

Ian Mackenzie
07-20-2006, 12:10 AM
Doods...

First, thanks for the detailed postings and even more congrats for the 2-yr long exercise. That is devotion. You and Ian look to have done one hell of a job. I wish I had reason to travel to Reno...!!

The quote confuses me. I've "heard" that from but a few members here, and don't get it. Were you able to collect any measurements of the response, before and after?

No, I don't think Ed has an RTA or a Clio for pre 4344 post 4344 response.

Could you post some plots? Also, you didn't post whether there is any EQ in the signal path, and if so what it is, and what corrections you might be imparting.

There is no graphic equ I am aware of, however the Mac preamp has facility for eq via tone controls

I ask because I just inserted a Bryston 10B in-place of the Ashly - but not for the reasons you did, nor with the results you got. I am trying to achieve what I understand is Greg Timbers' ideal active crossover application with a 4345 - use the active crossover in a biamp set-up to replicate the voltage drive of the original HPF (-12dB, 290Hz).

This would be much easier to discuss verbally.

Question: What was your reason for installing it? (Are the voltage drives from the Bryston tailered to those of the passive 3145 crossover for the woofer to mid range driver?)

My understanding you were happy with the Ashly.

The passive filter voltage drive maybe difficult to emulate. The actual active slope is 18 db as you maybe aware prescribed by JBL. Perhaps if someone fluent with Soundeasy could take those passive voltage drives and compute an active eq simulation and schematic ..Tim G comes to mind.

We could attempt to modify the 12 db slope with the new crossover to match the current JBL passive voltage drive but this has not been attempted. I will look at it but it will take some time.

At any rate the 18 db slope in conjuntion with the active crossover is subjectively superior.

I have not yet Smaart'ed this - I am waiting Widget's visit this weekend for some A/B, and don't want to corrupt the current set-up before I go fully into the Bryston config - but what I did get (admittedly NOT properly EQ'd and therefore results/opinions are not relevant), is seemingly improved tonality, and better channel separation. I say not relevant because in my soundguy work, I typically am confronted with a system that sounds either muffled or bright, or "veiled" or boomy, and have found time-after-time that proper measurements of room response and adjustments for that response vastly improve the character of the sound, and the perception of the system (and audience response and appreciation!). This is experience based upon Smaart'ing dozens and dozens of systems, often when I felt there was either no hope, or it was already so good there was little improvement that could be made. Wrong on both accounts.

Interesting observations;On the basis that the L pads are setup correctly the distinction in Ed's system (or the reference system) is not relevent to Eq flatness. The veiling (we both observed) refers to loss of information and Hf brightness. This is attributable to what happens in the signal processing. This being insertion losses from cables and terminations, transparency of signal processing electronics and the power amplifiers.

The "brightness" many attribute to Bryston, IMO, relates to EQ. Bryston may be more efficient in their reproduction of the HF part of the spectrum - therefore, systems not "aware" of that will certainly sound brighter.

Could be the case! We found ther setting up of all 4 drviers far more critical in terms of level matching.

Perhaps a process of elimination may assist here. Temporarily bypass the Eq 1/3 direct from the preamp to the crossover=>and power amps. Then switch in the EQ in flat mode but not bypassed and then alternate with the Ashly and Bryston.

The brightness could also be attributable to the source or even the power amps. Also look at the net spl method of setting up the Lpads, it works.

I've got measurements before this switch, and soon will Smaart with Bryston and share those.

As a post script, I spent considerable time (months) evaluating the active crossover using similar amps and obviously drivers and passive crossovers identical to Ed's.

Very subtle variations is the final part selection and usage in the active crossover provided a presentation that was both transparent and detailed without any sonic glare.

The Jeft differental pair & bjt discrete class A output used in the opamps in the crossover have characteristicly somewhat higher THD than the best chip opamps, typcially 0.05 % verus 0.005 distortion. (I hate bjt front ends in any amplifier, they lack detail and sound un natural to me imho). But they have other special qualities that are particularly attractive for audio.

Jfets are analogous to Valves and are known to be more transparent and offer finer resolution than equivalent BJT eqivalent designs. They also have low feedback resulting from low open loop gain


The final melt of the active crossover and the power amps is the essence of what happens, and of course the passive crossover parts and terminations. In this project we addressed all these areas to deliver a final result which I would consider neither warm nor dry, bright or soft sounding.

Because the various aspects of the signal chain are cascaded, its is often rather confusing to determine where the audible traits are attributable and for this reason changing out one component may or may not give the desired result.

Of course it depends on what you want and like. Some people like and prefer a bright detailed sound and that is fine if that is what you are looking for.

Ian

Tom Loizeaux
07-20-2006, 05:38 AM
I think this thread is an example of one of the best things about this Forum. Many of us have, or want to aquire some classic JBLs - so this kind of give and take information, along with lots of sharing of real experience on very specific issues makes the prospect of restoring and even upgrading these classics very attractive.
My thanks to all of those involved. Your time and work has elevated the value of this Forum.

Tom

Ian Mackenzie
07-20-2006, 08:00 AM
Tom,

Glad you enjoyed the read. Unfortunately none of this is a overnight exercise and it can be tedious.

But if you follow a logical process and execute each phase correctly the results can be quite rewarding..and its fun!

The next phase we propose is to consider fixed resisters to replace the variable Lpads once their settings have been verified. The Lpads are not a very precise way of setting up the drivers using the db markings on tnhe foil cals as Ed will attest to. Hence we measure and calibrate each drive one at a time

Incidentally the 4344 requires the mid to be attenuated -5 db from maximum, the horn and slot -6 db from maximum for proper alignment with the 2235H a best we can tell.

The rta is probably not accurate enough to compare individual frequencies. Hence the net method of maximium less a known amount is best for reading exact attenuation of selected spot frequencies. However if you did use an analyer you would find the overall response remarkably smooth! Using broad divisions like 12 db..I did and it sounded perfect. I find I can get a really smooth response with the net method far more so than using an analyser or RTA particularly when the system has a rather wiggely response like the 43XX systems. How do you find the mean response with a driver that varies +- 2-3 db with all sorts of peaks and bumps and dips?

Even with smoothing its an approximation and I am looking for 1/4 db or better precision matching of the actual sensitivities (levels) of all 4 drivers.

If you can get a mean value of SPL b/n left and right UHF, HF , and Mid then so both left and right are as close as manual measurement allows then we can consider measurement of the L pads to arrive at some fixed resisters values.

Note this may require 3 or 4 attempted readings to get a mean reading on the meter because of the sloppy nature of the Lpads.

The key is to get both Left and Right channels the absolutely same. You will just know when its right..the speakers drivers outputs will no be distinguishable from each other and the imaging will drag you in and engage you.

Ian

porschedpm
07-20-2006, 08:32 AM
Were you able to collect any measurements of the response, before and after? Could you post some plots? Also, you didn't post whether there is any EQ in the signal path, and if so what it is, and what corrections you might be imparting...

Hi, Bo. Sorry, beyond my trusty little SPL meter I didn't use, and actually don't have, any measurement equipment. (I'm open to suggestions on what would be good for the amateur, slightly more than casual home user, though) There are 8 bands of tone controls on my preamp but they're always set to flat.

I'm interested to hear how you like the Bryston. I realize Reno's a bit out of the way. I'm still loving my new set up, like a kid with a new toy. But later on, say in a few months, or if we ever have a Bay Area LH gathering, I might be able to be talked into bringing Ian's active crossover down for your evaluation and listening pleasure.

Ed

boputnam
07-20-2006, 08:50 AM
The passive filter voltage drive maybe difficult to emulate. The actual active slope is 18 db as you maybe aware prescribed by JBL. True, and correct. The specific 4345 cards for the 5234a have a -18dB slope. I talked to Giskard extensively about this aspect of the active 5234a. He reiterated a comment from Greg Timbers, leading me to elect the -12dB slope (as per my post). There is a risk of some loss of definition, and of overdriving the 2122H (due to the shallower slope of the HPF). Of the former - I am listening hard for this, but thus far have not discerned it after dozens of A/B's with the Ashly. To the latter - I sensed some overdriving of the 2122H (even at modest gain) and reduced the gain on the MF-HF amp, as Giskard suggested might be needed. He predicted that correctly.


We could attempt to modify the 12 db slope with the new crossover to match the current JBL passive voltage drive but this has not been attempted. I will look at it but it will take some time.I'd be most interested in your findings, if you ever do this.


At any rate the 18 db slope in conjuntion with the active crossover is subjectively superior.Yes, I agree. However, I here elected to follow the guidance of the 4345 designer, and try and emulate the voltage drive of the HPF in the original 4-way passive network. This -12dB slope was chosen by them after hours and hours of listening and tweaking. In "purist" approach, this Bryston has no switches - it is fixed at -12dB, 290Hz. It is a big change coming from the -24dB of the Ashly, but I cannot yet say definitively there is any loss of definition using the -12dB slope.

I've not yet tweaked anything. Widget plans to come 'round this weekend for some hearing sessions, and I'm interested in his appraisal.

Thanks for the comprehensive reply(s).

One last thing:

The veiling (we both observed) refers to loss of information and Hf brightness.This intrigues me, still. You've made so many improvements I wonder how much of this can be attributed to removing the Ashly, per se. This characteristic is something I am listening hard for, but can't verify this "veiling" in my set-up. I think our systems were quite different at the start of this Ashly comparison (mine is all balanced, XLR interconnects with very low noise floor). I think there is a bit more definition with the Bryston (at 3x the Ashly's cost, there should be...) but there is no loss of information in using the Ashly.

Chas
07-20-2006, 10:03 AM
One last thing:
This intrigues me, still. You've made so many improvements I wonder how much of this can be attributed to removing the Ashly, per se. This characteristic is something I am listening hard for, but can't verify this "veiling" in my set-up. I think our systems were quite different at the start of this Ashly comparison (mine is all balanced, XLR interconnects with very low noise floor). I think there is a bit more definition with the Bryston (at 3x the Ashly's cost, there should be...) but there is no loss of information in using the Ashly.


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Bo, not meaning to muddy the waters here, but in my triamp set up with Ashly's doing the 50 Hz L/P and 200 Hz B/P with a high quality passive network in front of my H/P amp instead of using active at 200 Hz (at only a 6 dB slope), there is a noticeable diffrence if I sub the Ashly in temporarily.

The same is true for my Ashly 1/3 octave EQ, it is relegated to operation below 200 Hz (I know, - what a waste!). It's audible when used full range in my system.

I have to agree with Ian too, on the BJT/JFet issue, my experience has been the same.:)

porschedpm
07-20-2006, 10:52 AM
...One last thing:
This intrigues me, still. You've made so many improvements I wonder how much of this can be attributed to removing the Ashly, per se. This characteristic is something I am listening hard for, but can't verify this "veiling" in my set-up. I think our systems were quite different at the start of this Ashly comparison (mine is all balanced, XLR interconnects with very low noise floor). I think there is a bit more definition with the Bryston (at 3x the Ashly's cost, there should be...) but there is no loss of information in using the Ashly.



I should add the "veiled" effect I heard when I did a with bi-amping and without bi-amping comparison. At the time I was using a Pass 250 amp for the LF driver and McIntosch MC150 am for the upper drivers in biamp mode plus the Ashly XR1001 . And in non-biamp it all ran through the Pass 250. Used the XLR interconnects in both set-ups. By veiled I didn't mean there was loss of detail. The detail was there but the music seemed less alive or less dynamic. As if someone was standing between you and the speaker. One thing I never ruled out though was how much of the veiled sound was due to the bi-amp switch on the 4343 itself. Or possibly, how much affect the Mac amp contributed. I never meant to infer that Ashly doesn't make good equipment. Given their price and flexibility they are good. I only ment that my system had evolved in quality/performance that it revealed the Ashly was not keeping up anymore.

Ed

Robh3606
07-20-2006, 10:55 AM
Hello Bo

I just swapped out an M552 for the DX-1 with XPL-200A cards. The active point for the XPLS is 250hz with 12Db slopes. I used it with the 4344's for a couple of weeks before I took the XPL's out of storage. The 4344's sounded great like this. I was considering building 4344 cards but I may not based on how good they sounded using the 12Db slopes in these cards. The 2122's seemed just fine and didn't give me any signs they were being taxed by the slope change or slightly lower crossover point. I am curious how you like the Bryston. As far as comparisons of the M552 to the DX-1 it's a no brainer. The DX-1 is better sounding especially up top on the 4344's. With the XPL-200 it took me a while to realize what was going on. They simply vanish with the DX-1. It's really uncanny the speakers just dissapear. All the spacial clues are more vivid and the sense of space improves.

Rob:)

boputnam
07-20-2006, 11:33 AM
Hey, Ed...

I completely agree - as you move up in quality, things fall away as being options. I expect this is true with Ashly - even though I've had very good luck with their gear in many applications - but they are certainly not "audiophile" calibre which is the realm you and Ian have taken us to. I haven't experienced quite what you describe - it may be I am not as sensative to that particular characteristic as you are, or something else in my signal path is obscuring the "effect". Possible...

Hi, Rob...

I've noticed improvements all the way along, as I've moved from at-first briefly using the internal 4-way passive, moving to bi-amp with the 5234a, then with the 552, and finally to the Ashly XR1001. Each step has been significant. There are differences now, but I don't want to be a mere subjective reporter - "I tweaked the knob therefore it sounds better". I really want to critically analyze the difference, subjective tho it is.

Chas...

To prove I do not have any bipolar disorder :p I agree on the QRX3102, although I do find it amongst the best analogue EQ's in it's price bracket. Sure, I wish the Q was higher and there were notch filters, but it is damned good as is. When I moved up to the DN370, however, the improvement was astonishing, validating all the love from users of KT / Midas out there. That said, I'm interested to measure the Bryston config response and see how much difference there is from the Ashly config. I hear differences, but am sitting on my hands for a few days.

To wit: Is this EQ "endemic" to the 4345's, or is it biased in the HF range to compensate for the Ashly? Dunno yet...

Chas
07-20-2006, 02:03 PM
[quote=boputnam]Chas...

To prove I do not have any bipolar disorder :p I agree on the QRX3102, although I do find it amongst the best analogue EQ's in it's price bracket. Sure, I wish the Q was higher and there were notch filters, but it is damned good as is. When I moved up to the DN370, however, the improvement was astonishing, validating all the love from users of KT / Midas out there. That said, I'm interested to measure the Bryston config response and see how much difference there is from the Ashly config. I hear differences, but am sitting on my hands for a few days.

Bo-
Good to hear we don't have to prescribe the Lithium yet!:p

Agreed, the Ashly is fine stuff, particularly in light of the price. I think I notice these things easily because I have spent a ton of time over the past 20+ years building and refining my electronics (at the expense of working on speakers) and I am very sensitive to various degrees of resolution, I suppose.

Is it measurable? hmm.....that's a damn good question....
Now I am embarking on a similar mission here with loudspeakers. Now, if I can just get my 4345's going:banghead: .

Ian Mackenzie
07-20-2006, 03:17 PM
True, and correct. The specific 4345 cards for the 5234a have a -18dB slope. I talked to Giskard extensively about this aspect of the active 5234a. He reiterated a comment from Greg Timbers, leading me to elect the -12dB slope (as per my post). There is a risk of some loss of definition, and of overdriving the 2122H (due to the shallower slope of the HPF). Of the former - I am listening hard for this, but thus far have not discerned it after dozens of A/B's with the Ashly. To the latter - I sensed some overdriving of the 2122H (even at modest gain) and reduced the gain on the MF-HF amp, as Giskard suggested might be needed. He predicted that correctly.

I'd be most interested in your findings, if you ever do this.

Yes, I agree. However, I here elected to follow the guidance of the 4345 designer, and try and emulate the voltage drive of the HPF in the original 4-way passive network. This -12dB slope was chosen by them after hours and hours of listening and tweaking. In "purist" approach, this Bryston has no switches - it is fixed at -12dB, 290Hz. It is a big change coming from the -24dB of the Ashly, but I cannot yet say definitively there is any loss of definition using the -12dB slope.

I've not yet tweaked anything. Widget plans to come 'round this weekend for some hearing sessions, and I'm interested in his appraisal.

Thanks for the comprehensive reply(s).

One last thing:
This intrigues me, still. You've made so many improvements I wonder how much of this can be attributed to removing the Ashly, per se. This characteristic is something I am listening hard for, but can't verify this "veiling" in my set-up. I think our systems were quite different at the start of this Ashly comparison (mine is all balanced, XLR interconnects with very low noise floor). I think there is a bit more definition with the Bryston (at 3x the Ashly's cost, there should be...) but there is no loss of information in using the Ashly.




Okay I get it: I was not aware the Ashly was 24 db slope.

So did you have Byston adjust and spread the crossover points for 12 db slopes or is it 290 - 3db?..As I recall the spread is about 240 hz low pass ..and 290 high pass (I would have to check my files to verify this).

I assume you are driving the low and high pass in phase .

Balanced:

"My signal path is balanced from the preamp onwards."
My preamp is different for sure.

Veiling:

Veiling meaning to cover up..yes. Take away the barriers of resistance and you get more information, less greying out of signal, bit like taking off grill covers with a tight weave fabric. I agree with Ed that it sounds more alive and dynamic.

As absurd as I might be taken I found using pure copper terminations with heavy gauge copper wire seemed to impart less veiling as opposed tin plated. large crocodile clips. This seemed to impart better transients otherwise sounding fuzzy and compressed. One can only resonably assume removing that biamp switch reduces insertion losses.

What I also found was that with each fundermental update the unconsious desire to doubt or make changes became less and less.

Ian

Other upgrades:
Bo, have you updated the crossover capacitors?

Tom Loizeaux
07-20-2006, 06:43 PM
I keep hearing about the JBL DX-1, but can't find any info on this crossover...anywhere!
Any leads?
Thanks,

Tom

johnaec
07-20-2006, 07:29 PM
JBL DX-1Manual and schematic in this thread: http://audioheritage.org/vbulletin/showthread.php?t=48&highlight=dx-1+manual

Lots of other info if you search.

Word last year was that JBL had some 100 or so units stashed in the Far East, and Giskard was designing new cards for their eventual use. Then it was determined that JBL just threw them out, causing Giskard to self-destruct for a few weeks, but he eventually came to...

John

Robh3606
07-20-2006, 07:38 PM
Hello Tom

The DX-1 goes back to the XPL line in the 90's. It was the companion active crossover developed for the XPL-200. It was latter used with the K2 series and personality cards were made for the 5500 and 9500 speakers

http://audioheritage.csdco.com/vbulletin/showthread.php?t=1908&highlight=DX-1

They are still used by Greg Timbers when he does R+D and he has one in his home system. They are few and far between as only one run was ever manufactured. Most that are still floating around don't have cards which JBL no longer has. They are easy to build though.

http://audioheritage.csdco.com/vbulletin/showthread.php?t=11024

I was lucky to get one from Mike Cadwell about 2 months ago. If I ever see another one I would grab it in a heartbeat. It is one very nice crossover.

Rob:)

boputnam
07-20-2006, 08:35 PM
Bo, have you updated the crossover capacitors?I am extremely fortunate that Giskard offered, and is hand-making the updated 3145 per his and Greg Timbers discussions on current topology. This will be fitted into the mountings for the existing 3145, bypassing Lpads and the biamp switch.

IMO, this is a merited upgrade to these wonderful 4345's - it's like being able to revisit the past with current technology and best practice. I'm fortunate all prior owners of these were so careful in their care - not the least of whom was Ken P. I am indebted...

boputnam
07-20-2006, 10:02 PM
I was enjoying these 4345's and my current set-up, and pondering the "perception" of my recent posts. The iterations we are discussing here are at the extreme end of appraisal. To some they will matter a great deal; to others the change will be less perceptible.

But, to clarify any possible confusion in my posts:

- the Ashly set-up I had was remarkable by any standards. It far surpassed any other system I have heard, save the most recent iteration of Project Widget. SO many visitors to these 4345's have marvelled, and this has become a local for audio appreciation. What a burden!! Anyway, it was not merely my opinion, it was palatable. That said...

- the Bryston seems to have better voicing / tonality and more of what I would call "ambience response". Perhaps this is encompassed by a lack of "veiling" - I do not know. I do know that the -12dB slope is not an issue - it may actually help voicing in the critical crossover region. More listening to do... I am really getting thrilled to be replicating the orignal design, and be improving the character of the response of this system.

As a side bar - Project Widget is, IMO, incomparable. There is an imaging depth to the TAD horns that is truly mind boggling. At the least it seems on the order of 10-feet; Widget posits that at times he "sees" source material from behind the listening position. I do not doubt it - it is a remarkable experience. I have not yet achieved that depth of imaging, but believe I am hair-breadth close in voicing and tonality.

What's playing now that prompts this post? Joni's "Travelogue" - a compelling blend of vocal, orchestral and jazz instrumentation and performance.