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Ian Mackenzie
02-21-2004, 07:07 PM
Under Construction

This thread will be dedicated to those members wishing to construct the vintage JBL 4345/4344 Professional Series Studio Monitors.

Over the next few weeks I will document blue prints (in JBL Blue..LOL) and provide a Step by Step Guide to Enclosure and Crossover Network Design & Construction.

Some of you will have already been this route with the 4343 so please your collective wisdom and knowledge is most welcome

Ian Mackenzie.

:cool:

JuniorJBL
02-21-2004, 08:30 PM
I have always wanted to build a pair of 4345's just because I used to listen to them at my favorite pro shop when I was a young teen. My friends mom worked there and that was our hang-out! The most I could afford was a pair of 4301b's from her JBL sale for employees. 129.45 for the pair. that was a lot of money for me at the time. I must build. Thanks again!!
Shane:thmbsup: :spin:

Robh3606
02-21-2004, 08:41 PM
Well you know I am interested. Took me a while to get the drivers but I am finally ready now so I am all ears!!!!


Rob:)

Ian Mackenzie
02-21-2004, 11:53 PM
Just a teaser until I gather the information in a usable form.

Ian:D

ngccglp
02-23-2004, 01:38 AM
I am new to this forum and am already quite fired up. If my deal on the 4333A don't go through, I am also tempted to build the speakers myself.

However, if I decide to build one, I will go all the way and maybe build the 4350. I will probably out source the cabinet building to a professional carpenter and install the drivers/crossovers myself.

Anybody can advise me where I can get the cabinet plans and drivers, crossovers etc?

Thanks.

David

Ian Mackenzie
02-23-2004, 02:55 AM
David,

There are a number of experienced members who have walked the 4350/55 road before you, suggest you do a search and post in one the 4350 threads.

But before you leap, consider you current and future requirements and situation, larger is not necessarily better..do some research.

I have previously built (some 25 years ago) the 4343 and can attest to its performance for 90+ % of most domestic needs.

The 4344 is more refined and the 4345 a larger version with added sensitivity and a bit more extension. Both these designs are more manageable in use and construction over the 4350

Ian

Tom Loizeaux
02-23-2004, 05:22 AM
David,
I understand that the JBL 4344 Mk II is available outside the US. You might want to look into a pair of these . Though they may cost more then the 4333 you've been looking at, they certainly will be less "trouble" then building your own...and these sound very nice from what I've heard.

Tom

ngccglp
02-23-2004, 03:19 PM
Dear Ian and Tom,

Thanks for the advice. In fact I have been doing some surfing lately and found a couple of good deals on the 4344 in Japan. But most shops do not want to go through the trouble to air freight them to Singapore.

Agree that building is a lot more trouble. Also don't know if I will be able to get all the parts together. I went to ebay and did some search, and most of the parts required don't seem so easy to acquire.

Our papers run a local classified ads. I'm thinking of throwing the bait out this weekend to see if anybody is willing to part with theirs. I have a feeling I will not rest until I see the cool blue baffles in my living room.

Sigh...
David

Alex Lancaster
02-23-2004, 03:42 PM
David:

Go all the way!, for the 4350s, with better components, I know Mike Caldwell can help with the horns and lenses, JBLDog has NOS Xovers (The Hog), I think Ken Pachowski has the 2202s,
for 2405s and 2235s, eBay.

Look up the threads about bypass caps or charge coupling the 3107s here.

It will be a hybrid because of the newer components, IMO better.

Now, all You need is to fly Ian Mc or the other artists here, to make the cabinets, etc.

Alex.

Robh3606
02-23-2004, 03:50 PM
Hello David

If you decided to go the build route one thing you certainly would not find are the crossovers. Any other component will eventually show up on E-Bay. NOS crossovers for the monitors asside from the 3107's recently in the Tent are not that common. When the older system get parted out they will come up but 4344/4345 or 434X series don't seem to get parted out that often. I wonder why :idea:

Rob:)

Ian Mackenzie
02-24-2004, 12:50 AM
What I think what will work best is to introduce this topic in weekly instalments over say 6-8 weeks in an informal diy chat basis.

Aside from the drawings and how to interpret them, there is a lot of detail to be covered in terms of actual fabrication and quite of few tips along the way.

I will also attempt to explain just why these monitors are put together a certain way with references to the Library and pdf documents posted previously by our resident JBL insider Giskard.

So all in all it should be fun and informative, and you can pop in at any stage and pick up on the chat as all will be recorded in the previous posts.

Obviously some of you will be starting think about collecting your driver sets. This is half the fun and can take a little while. My first tip is it ain't impossible to find these gems and here is a clue

"As to selection an sourcing of drivers, that will be largely up the reader and I would suggest you search the threads for details of the midrange driver (2122h) and how it maybe created from a recone" i.e.

Quote from Giskard

"You can recone K110's and other LE10 cores as 2122H's, search for other threads dealing with that issue. Recones for these excellent midrange transducers are no longer cheap either. "

The sourcing of the drivers can take a little while as mentioned above, try the market place on the forums, Mike Caldwell, Ebay and even Jammine Jersey...they just come along with a little patience.

Oh and if you stray from the flock its at your own peril, this series will be about the authentic original designs, not mutants or hybrids

While you are doing this you can eagerly start preparing the enclosures. Next week is will start with overall box dimensions and publish the first in a series of blue prints

ian

ngccglp
02-24-2004, 04:11 AM
Alex,

I am OK with the idea of hybrid. There is a question: What are the substitutes drivers and are they easily available?

A comparison table will be fine. Thanks.

David

Robh3606
02-24-2004, 04:56 AM
Hello Alex

Well as far as driver substitutions the 2235/2245 are readilly available. You can either buy the drivers outright or build them up from frames. With these 2 systems I would have to say that aside from the 2231A/H there are none for the lowend.

The midrange drivers are listed above with the exception of the 2120/2123/2012. Any substitution with these drivers will require network changes.

Any 1" compression driver that can accept the 2307 will work. The 8 ohm versions will need a network change. So that list includes Le-85, 2420/2421/2425/2425S with 1" adaptor, 2426, 2427 with 2"adaptor removed and 1" adaptor installed, 2416 with 1" adaptor.

The 2405 and the 077 can both be used.

TimG
02-24-2004, 06:01 AM
If anyone is interested in building a hybrid version of the 4355 with JBL's newest, lowest distorion drivers, I would be willing to help develop a crossover and cabinet tuning once Don's Project May speakers are completed and delivered.
Here are some suggested drivers

4355 hybrid
Woofers: (2) 2235H $326 each or (2) 1500FE $510 each
Midbass: 2012H or 2020H about $250 each or 2251J ?$600?
Compression Driver: 2430 $275 2332 horn $50 or S4800 horn ?
Supertweeter: 045Ti ?

4348 hybrid
Woofer 1500Fe
Midbass 2012H
Compression driver 2430
Super tweeter 045Ti

I almost forgot, another alternative woofer could be the HS136, which is based on the 2226 motor. It uses a currently available recone kit but it also requires an additional bucking magnet to be added to the back of the motor. This driver was used in the Sythesis S2S subwoofer. Here is a link to a picture http://www.dvdstore.at/DVHS/S2s.jpg It will work in a cabinet volume similar to the 2235H but would require a different tuning. I will see if I can figure out what size magnet needs to be added to the back.

Alex Lancaster
02-24-2004, 06:53 AM
David:

I posted all the parts before, and all drivers are ferrite, Alnicos might need re-magnetizing, too much hassle.

per side:

2 2235H or E130/E140, 2205/25, 2231 reconed as 2235H
1 2202H or E120 "
1 2445J
1 2405H

All are available.

You could go as Tim suggested, but it would be expensive and complicated.

Alex.

TimG
02-24-2004, 07:36 AM
Alex:

I found out the hard way that the E130/E140 use a stronger magnet than the 2225/2235 and thus result in a hybrid driver if reconed as a 2235. You would have to measure one to determine how it would change the cabinet tuning and response. It would probably make the high frequencies slightly more efficient and reduce low end response slightly.

Alex Lancaster
02-24-2004, 09:39 AM
You are right, 1.35T vs 1.2T, but I have done it, and could not hear any difference, it probably would come out with lab measurements, but I still would do it.

Alex.

Ian Mackenzie
02-24-2004, 11:24 AM
Just to help focus the newby's, I was referring the search function in the technical forum s, there are oodles of threads talking about how to building up either the 2235 or 2212H.

Regards the compression driver the 2421 is available SH occassionaly but the 2425/2426 can be used.

Neither the 4344 or the 4345 will perform as stated without the true driver set. I said above there is no need to put in alternatives, if you do the final response will vary from the original. This will require complex network re design, again there are some threads that talk about this but it hardly seems worth while building a hack version unless you already have alternatives on hand and want to use them

The recones are available for both fom JBL, if you ask nicely Giskard maybe able to assist you.

Ian

Guido
02-24-2004, 11:26 AM
Hi David!

What about the 4435?

The drivers are much easier to get as the 2426 is still available and the 2234 could be reconed from several transducers ...... do a search.

The 2344 might be a problem but there is a copy out there from P-Audio (PH316).
Or you choose the new Waveguide which I will do in my 4435 project.
see http://www.audioheritage.org/vbulletin/showthread.php?s=&threadid=1730

boputnam
02-25-2004, 06:20 PM
:wtf:

I am a dope. I have now confirmed that every batch after the original is botched. Completely :smsex: Somehow, a component (the secret one...) was omitted. Throw the shit away. The moronic Paint Master cannot replicate his batch even with his formulae, in his handwriting. Imagine my displeasure...

So, in the words of Paul McCartney*, "we start again". I will drag the 4301B's back down to the toothless one, and give it another go. If this fails, or even if not, I may banish myself, forever... :die:

* - Paul McCartney, Unplugged (the official bootleg), 1991, MPL (EMI), UK release of the MTV session, Limehouse Studios, Wembley, 25 Jan., 1991.

Ian Mackenzie
02-25-2004, 06:26 PM
Bo,

don't get too stressed,

Ian

boputnam
02-25-2004, 06:40 PM
I'm REALLY pissed. I made special effort, and even TIPPED the dope! He was too chatty - I shoulda recognized the increased risk with increased chatty. Obvious, now...

Mr. Widget
02-25-2004, 06:56 PM
I thought the color problem was similar to the toilets running backwards down under.:D :D

JBL Blue MUST be applied in the Northern Hemisphere and preferably in California.:eek:

Ian Mackenzie
02-25-2004, 07:01 PM
Ha Ha Ha

No no Widget, you are getting confused with flushmatic clearner...hospital grade.

Bo....My advise is tell this F&^%$#g C%$T his balls will be dark blue back if he does not deliver (demand a full refund or rippem right off..his balls )

Ian

boputnam
02-25-2004, 07:43 PM
Even better, my friend, will be to curse him to eating Vegemite forever - afterall, that IS the color he produced, afterall... :rotfl:

herve M
02-27-2004, 12:15 PM
Tim G "4355 hybrid
Woofers: (2) 2235H $326 each or (2) 1500FE $510 each
Midbass: 2012H or 2020H about $250 each or 2251J ?$600?
Compression Driver: 2430 $275 2332 horn $50 or S4800 horn ?
Supertweeter: 045Ti ?

4348 hybrid
Woofer 1500Fe
Midbass 2012H
Compression driver 2430
Super tweeter 045Ti
:

Tim G, Where can to buy 1500Fe and 045Ti ????

HerveM"

Ian Mackenzie
02-28-2004, 07:11 PM
Just to avoid potentiai off topic threads end trails here, can we perhaps start a new thread for those thinking along the lines of 4435/4350/4355's.

There is certainly plenty of virtues in these particular monitors but it would be better to offer depth of coverage of the 4344 & 4345 for those that are keen to construct such traditional "Precision JBL Monitors"

Ian:)

Ian Mackenzie
02-28-2004, 08:08 PM
As an intermediate step between outlining the thread and actual construction plans I thought it would be useful to post some information/details about what to expect from the JBL 4344/4345 project and also examine the question of which project should I build.

No doubt some of you have longed to buy/ or make such a design but never heard one actually go.

Okay, there are a whole string of JBL 43xx series monitors and the best source of detailed data is a our very own Heritage Library.

Its worth reading though the brochures to get a feel for what the monitors are about and also the product/people profiles of Greg Timbers.

My take is the 4344/4345 was the last of the sophisticated medium format 4 way monitors JBL manufactured which were more refined versions of the earlier 4341/4343/4343B monitors.

The basic idea of these designs was to offer most of the benefits of the larger flagship 4350 model but in a medium format for less large studios of that time. The concept revolved around deliberately limiting the operating bandwidth of the individual drivers, thus maximising the optimum benefits of the drivers in terms of transient response, clarity and power handling.

The trick was to blend the drivers perfectly in such a way as to provide a smooth response and coherent sound stage. But up until this time that was not thought possible.

However, JBL's Greg Timbers developed a rare talent for the blending of these multi driver systems to the point of it becoming an art form. The JBL L250/Ti is another notable multi driver system designed by Greg Timbers from the JBL Consumer Series. (see the Heritage Library for references)

Obviously the crossover network is a key ingredient in the overall system and I will devote detailed discussion of its construction later on in the thread.

So we have this snazzy multi driver monitor using now vintage components. But what does it deliver?

For a moderate outlay in S/H or reconed drivers you will have something pretty special and a timeless classic JBL monitor.

The 4344 is a big step up in accuracy from the popular 3 way 4333/A with the added 10 inch 2122H mid cone. The 4344 also uses an advanced crossover network & a shorter 1200 hertz high frequency horn, together they provide transient definition and instrumental clarity that beyond comprehension.

The larger 4345 monitor sports an 18 inch 2245H woofer in a 9 cubic ft enclosure and has 2 db more sensitivity (95 db) than the 4344 and slightly more bass extension.

For comparison with other systems...

Earlier in my audio career I built the classic 4 way 4343* (circ 1980), then in more recent years a 3 way Lansing / JBL system with the large 2397 Smith Horn & 2405 Slot Radiator, and later added the 10 inch 2122H JBL mid cone to make a 4 way system.

The improvement in adding more drivers in a properly blended system was remarkable.

I then changed out the 2397 and 2405 for the 2344 Bi Radial Horn and it was again a 3 way design with reduce time alignment issues (20 inches ) between the Horn and Slot.

On hearing in comparison the original 4343 system some 23 years on, I immediately scoured the world for the 2307/2308 Horn Lens assembly and a Slot Radiator so that I could re create that special something that the classic 4 way JBL monitor delivers.

The current state of art in crossover component quality now further advance the Legacy of the Classic 4 way JBL Monitor to a new levels of precision.

Some of you will be weighing up whether to build up the simpler contemporary 2 way 4430/4435 monitor or the more complex JBL 4344/4345 classic 4 way precision monitor.

That is a personal decision that you alone will have to make.

I will continue with posts of the box design in the next few days.

Ian

:cool:

*In 1980 I felt it was necessary to have a decent hifi for my 21st birthday and on seeing the brochure I fell in love with the 4343 and decided to build a pair. They now reside with my brother and are affectionately referred to "The wife".

mikebake
03-03-2004, 03:07 PM
Originally posted by TimG
Alex:

I found out the hard way that the E130/E140 use a stronger magnet than the 2225/2235 and thus result in a hybrid driver if reconed as a 2235. You would have to measure one to determine how it would change the cabinet tuning and response. It would probably make the high frequencies slightly more efficient and reduce low end response slightly.

That is exactly one of the pairs that I have; E130's with 2225 paper. I've thought of having Giskard analyze the result, but your prediction seems accurate.

Ian Mackenzie
03-06-2004, 12:14 AM
A status update.

At the moment I am researching the original construction techniques used in this series of monitors.

So far, looking at available information kindly submitted by subwoofer...on the 4343, the type of side/bottom joint construction...a combination 45 angle mitre with locking sleeve and some other issues appear inappropriate and probably unattractive to would be project participants.

So we are looking at alternatives hence the hold on publishing any blue prints for the moment.

The most likely approach given most of us have a router (you would need to buy one for the baffle cutouts and it is an indispensible tool) is the attached image showing a basic sketch of the simple rebated butt lock joint.

The other red line drawing is a side elevation of the baffle rebate inset into the sides. The welded glue joint with additional cleats would make a very rigid enclosure. The top,sides , front and rear would be assembled together, there being a rear boot panel for service access.

Assuming some reasonably precise cutting and routering with uniform panel dimensions, the enclosure would be squared and trim at assembly and make the assembly straight forward.

Additional cleats can be used and of course would be necessary if you were to use the simple butt joint.

No doubt many of the experienced cabinet makers on the forums can devise some fancy and perhaps more sophistication joint construction but at the end of the day it has to be something the average diy speaker guy can put together.

I hope to have this sorted in a few days.

As I mentioned earlier..feel free to comment...this is a community Project

regards

Ian:cool:

Tom Loizeaux
03-06-2004, 11:09 AM
Ian,
Thanks for a nice overview of the 43XX monitors. These broader looks increase our understanding and appreciation of these classics.
From my limited knowledge and from what I learned from the Heritage Site, I see the 4343, not the 4344, as the "junior" version of the 4350/55. A number of catalogues show the 4345 and 4343 as options to the "flagship" 4350/55, but no where do I see the 4344 shown, listed, or even mentioned! I feel the 4343 should be used as the "15 inch" equivalent of the 4345. I suspect that the 4343 was the most prolific, with the 18" 4345 comming in next. My guess is that there simply weren't very many 4344s made. I've heard that the 4344 is a slightly "improved" version of the 4343 because it uses ceramic drivers and has a slightly "improved" crossover (adding bypass caps, if nothing else). I suspect that, because the 4344 didn't have to work in the "rotatable top panel", the 4344 may have placed the drivers in a slightly more optimum position ? In the lineage of JBL studio monitor development, the 4343 was the design that added the 10" mid-bass driver, used the shorter, 1200Hz 2307 horn, and established the "narrow bandwidth" idea over it's predecessor - the 4333.
It's interesting to hear you, as well as many others, say that the 4-way design using a combination of a quality woofer, 10" mid-bass, compression driver, short horn w/ lens, and slot tweeter was one of the best designs to come from JBL.

I am curious to hear the 4344s, but I'm happy enough with my 4343s that I don't know if the 4344s will be a significant enough improvement.

Tom "cautiously seeking sonic perfection"

4313B
03-06-2004, 11:43 AM
"I feel the 4343 should be used as the "15 inch" equivalent of the 4345."

Well that's not even debatable; the 4344 is the 15-inch equivalent of the 4345.

Given the recent awareness of how the stock 4344 was constructed though, I would strongly urge using the 4343 enclosure as a basis to build a "4344" clone. The ONLY component differences between the 4344 and 4345 are the 15-inch 2235H in place of the 18-inch 2245H and the two different foilcals. The 2235H in the 4344 is an evolution of the 2231H in the 4343 and the 2122H in the 4344 and 4345 is an evolution of the 2121 in the 4343. The newer 3144/3145 filter of the 4344/4345 is also argueably a better design than the 3143 in the 4343.

"the 4344 may have placed the drivers in a slightly more optimum position"

I wouldn't bet on it. The network in the 4344 is IDENTICAL to the network in the 4345 and nothing was done to compensate for the decrease in baffle width or the different arrangement of all the transducers with respect to the baffle edges. Again, I would use the 4343 enclosure and transducer arrangement to build a 4344. Oh wait... I already did that... numerous times... and it freakin' works.

"I am curious to hear the 4344s, but I'm happy enough with my 4343s that I don't know if the 4344s will be a significant enough improvement."

Cool! Whatever floats your boat. The 4343 is no slouch at all. It's just a natural "evolution" to upgrade the 4343 to the 4344's 15-inch driver, 10-inch driver, and crossover network. No different than upgrading other systems such as the L250 to the 250Ti. Been there, done that, bought the T-shirt and used it to oil the black walnut veneer. The really cool thing is one can recone both the ferrite 2121H and the ferrite 136H/2231H as the newer drivers and be done with that part of it, in fact one doesn't even have a choice as far as the 136H/2231H goes.

speakerdave
03-06-2004, 11:49 AM
"used the shorter, 1200Hz 2307 horn"

Couple of questions--

Do you think this was done for a sonic improvement or to accommodate cabinet dimensions?

Are the crossovers for these speakers (4343,4345,4344) specific to that horn? That is, if the horn were changed to the 2312/H92 (JBL describes it as having a "smoother performance and is preferred if enclosure depth is adequate for mounting") and the drivers and frequency division kept the same, would an adjustment in the crossover be necessary?

Thanks,

David

Addendum: Drew Daniels says that transition from a cone to a horn is better if the horn is "well-behaved" below cut-off. I'm thinking he means crossover frequency? That would be one reason for me considering this change. The H92 is good to 800, crossed over at 1200--wouldn't that contribute to smooth transition? My proposed cabinet design would accommodate the depth.

4313B
03-06-2004, 12:07 PM
The HL91/2307 came first. The HL92/2312 was developed because the HL91/2307 doesn't do real well when forced to go down to 800 Hz to meet a 15-inch LF transducer. The shorter HL91/2307 is the better choice in systems like the 4343, 4344, and 4345 where it is crossed over higher.

The HL93/2311 is arguably the best choice of the "fog horns" (JBL engineering term) and one worth examining. A perfectionist would probably tweek any filter to make up for the change in horn depth. The HL92/2312 has an ass load of delay, the HL93/2311 has the least amount.

If you are building all this from scratch you are immediately freed from various constraints. You can forge ahead and make all new mistakes, you can remain true to the past and live with the same old mistakes, or you can go with something in between. It's your time and your money :)

I'd be real inclined to do a 4343 enclosure and the 4344/4345 components/filters. I'd also try to work in the 375/HL93 in place of the LE85/HL91 and see what happened.

speakerdave
03-06-2004, 12:15 PM
Thank you for that.

David

Ian Mackenzie
03-06-2004, 09:24 PM
Giskard and I talked about the pros/cons of both the 4343 and 4344 enclosures today.

I will publish a cabinet design soon enough. This will be derived from the 4343 cabinet dimensions but with best practise design/construction for forum members. The baffle layout will have offset drivers like the latter 4344, but the woofer will also be offset and the ports next to it, this being a better engineerig solution.

The 4343 is an excellent system, perhaps the virtue of the 4344 is the offset driver configuration offering arguably better imaging and smoother response where the cabinet is not sofit, or flush mounted as is often the case in a studio.

Those of you who are lucky enough to be proud 4343 owners may therefore opt for an enclosure upgrade and perhaps a recone of the 2131A and upgrade to the 2122 if you can arrange this, along with the 4345 network.

The rest of you will have an open choice, the offering will be the best of the best.....

On that note I will stress in the following posts the use of the highest quality film foil capacitors such as Hovlands in the crossover network, metalised polypropolyene are inferior and will Not extract the full transparency and clarity of the 2307/2308 exponential horn or the Slot Radiator.

If you really seek to further impress your ears and enjoy the golden years they have left, I may be enouraged to offer a very high performance active crossover and a balanced SE class A amplifer exclusively to forum members. (in a private thread)

The synergy of this amplification and the inherent design concept of these 4 way monitors is pure JBL Nirvana at the highest level...but more about that later.

bye for now

Ian:D

boputnam
03-07-2004, 06:47 AM
Originally posted by Giskard
If you are building all this from scratch you are immediately freed from various constraints. You can forge ahead and make all new mistakes, you can remain true to the past and live with the same old mistakes, or you can go with something in between. It occurs to me we need a special thread to archive this invaluable wisdom... :thmbsup:

4313B
03-07-2004, 06:50 AM
Sure we do ..... :rotfl:

subwoof
03-09-2004, 05:22 PM
I just built a pair of new frames to replace the ( now destroyed ) particle board originals...

Here are a few pics:

Ian Mackenzie
03-11-2004, 04:08 PM
Sorry for the delay, I will post the drawings tomorrow.

I have been trying to use a drawing package (Visio Pro), but as a newby to this package its more trouble than its worth.

So the drawings will be accurate, but not of architectual scale...forgive me.....Some of you who are dab hands with a Cad package may wish to tart up the pfds, we can then archive them into secure place on the forums.

More later.

Ian

boputnam
03-11-2004, 06:11 PM
Hey...

I've got AutoCAD 2004, but cannot profess to be proficient at (with) it. But, Giskard has done some dandy work, the Widget too. Maybe a suitable bribe could be arranged...

Vegemite?

NOT!! :no:

Ian Mackenzie
03-11-2004, 06:23 PM
Vegemite....


Yep I wil be bring a few jars with me..thats a given.

Do what you have to do I say

Ian

ngccglp
03-11-2004, 11:07 PM
Ian,

I am also interested to learn how to build my own speakers. But I don't think I will ever manage to build a cross-over. I am thinking of getting a electronic crossover to solve this problem. I can then get used power amps to drive the drivers actively.

Is that possible?

David

Ian Mackenzie
03-12-2004, 01:06 AM
I am also interested to learn how to build my own speakers. But I don't think I will ever manage to build a cross-over. I am thinking of getting a electronic crossover to solve this problem. I can then get used power amps to drive the drivers actively.

Is that possible?

What........? Balls......they are not hard to make.

Some simple skills in the case of the 3145 ..a factory design, careful selection of components and you are home. If you are plan a to build up this project or another JBL vintage design we are here to help you....just ask.

This system can be bi amplified to improve dynamic capability under hi drive conditions but it does involved a bunch of extra amplifiers, cables etc and often is difficult to control hum and noise unless care is taken.

If you are starting a raw design from scratch talk to one of our knowledgeable members about your plans...I am sure they would be happy to assist where they can.

Ian

ngccglp
03-12-2004, 02:14 AM
Alright then, I'll start by keeping a close track to this thread and learn whatever technical lingo there is to learn about cross-over.
Thanks.

David.

Robh3606
03-12-2004, 05:00 AM
Hello David

I run an all active set-up because I am weak with passives. I realized early on how difficult it was to get it really right on your own. I like to try new drivers and fiddling and voiceing a passive crossover is an art. That said if you are clonning an existing system and you have the crossover schematic there is no reason not to give it a go. You have a baseline, it is a great learning experience and its fun if you like to tinker. I will also be building up a pair and in this case I will be using the JBL designed crossovers.

Rob:)

andresohc
03-12-2004, 09:13 AM
Ian, I am attempting to build the 4345 (probably mostly inspired by your posts) and wondered if you have posted somewhere the parts list for your system (the crossover components you purchased, your board layout, your actual speaker elements you are using, whether you modified the crossover significantly from the original JBL circuit, if so your schematic) Any direction to the posts would be great. Thanks for taking the time to document and post all this.

Ian Mackenzie
03-12-2004, 12:12 PM
What,

Another one comin out of the wood work.....LOL.

Okay,

I will cook up a list shortly...have you already built the cabinets?

Looks like another JBL weekend coming up...LOL

Ian

Ian Mackenzie
03-12-2004, 10:06 PM
Here is the first of a series of line drawings for making the 4344 enclosure. The simplified drawing below shows the overall baffle dimensions, cut-out centres and cut out diameters.

I based this layout on the 4345 with consideration of the smaller 15 inch 2235 driver.

Some detailed discussion is in order.

The overall baffle height is almost identical to the 4345 and the exterior dimensions account for a 1/4 routered section into the top and sides.

As you can see the woofer has been pushed over in line with the midrange and horn to minimise standing waves that may otherwise occur with equidistant placement with the adjacent side walls and the ports positioned beside the woofer.

The level pads are repositioned below the 2405 which has also been raised a little in accordance with the 4344 layout. To compensate for the size of the15 inch 2235 driver in the lower baffle region the overall position of the driver set has been lowered an inch to give balance to the layout. Thus the modified position of 2405 retains perfect ear height for its vertical dispersion.

This drawing is rev0.00 and I anticipate discussion from you guys after which it can revised. If some wishes to tart up the final revison with a Cad package that would be nice.

I will post the other drawings in a day or two.

jarrods
03-13-2004, 01:27 AM
Hi Ian,

Could you please elaborate on the 1/4" routered you mention.

Also I take it from various posts I have seen on the forum, and your comments above, that this type of off centre mounting of the 15" is better sonically than the central placement as in the 4434 MkII. (Could the rational of centralizing it in that model based on aesthetics??? - surely not!)

thx jarrod

Ian Mackenzie
03-13-2004, 02:12 AM
Okay,

The baffle has to fix to somthing or it will fall out.

This can be done several ways but the most elegant solution and the one JBL uses is to router / rebate a channel all the way around and inset to the sides/top/bottom the thickness of the front baffle. Side stiffeners the full depth of the enclosures finshe the job.

The effect is strong and rigid structure which will also be square when the cabinet is assembled.

Regards the reason for the woofer being off centre, standings wave are the issue causing potential response peaks/dips.



Ian

4313B
03-13-2004, 02:58 PM
"Could the rational of centralizing it in that model based on aesthetics??? - surely not!"

Absolutely! Numerous JBL systems were based on that rational.

jarrods
03-13-2004, 03:16 PM
OK, got it.

I was going to make the back recessed in like that but have the baffle screwed on to a recessed bead to allow access into the box.

I see in the exploded view posted of a 4343 that JBL fit the back recessed, the lower bass driver baffle recessed, but the top mid/high baffle is not recessed and appears to be screwed to a 25x18mm bead that is recessed. I may adapt this composite idea to my 4344, but then you see screw heads from the front.

-jarrod

Ian Mackenzie
03-13-2004, 04:53 PM
Originally posted by jarrods
OK, got it.

I was going to make the back recessed in like that but have the baffle screwed on to a recessed bead to allow access into the box.

I see in the exploded view posted of a 4343 that JBL fit the back recessed, the lower bass driver baffle recessed, but the top mid/high baffle is not recessed and appears to be screwed to a 25x18mm bead that is recessed. I may adapt this composite idea to my 4344, but then you see screw heads from the front.

-jarrod


Jarrod,

I sense you are eager to get started...... all will become clear shortly...... best not to rush as this project is much bigger than it looks and mistakes can be hard to undo.

Regards the access, it is planned that the upper portion of the rear panel be removeable for servicing of the HF and UHF drivers.

The 4343 front panel for the mid, HF and UHF was made to be rotated for side mounting if required. I doubt if this feature is necessary or desireable for home listening.

Whole removeable panels are not recommended and unnecessary; fitting them up to be removeable is often less than neat in appearance, yes the screws will show and screws and holes tend to shear, leaks are more likely to happen. If all the drivers are removable why have removeable baffles.....

I will post the side elevation tomorrow night with all internal dimensions.

Ian Mackenzie
03-13-2004, 05:44 PM
Originally posted by andresohc
Ian, I am attempting to build the 4345 (probably mostly inspired by your posts) and wondered if you have posted somewhere the parts list for your system (the crossover components you purchased, your board layout, your actual speaker elements you are using, whether you modified the crossover significantly from the original JBL circuit, if so your schematic) Any direction to the posts would be great. Thanks for taking the time to document and post all this.

Okay,

Drivers:

2245H
2122H
2420 with 2425 diaphram
2405 Alnico

Crossover: The schematic is available from the jblpro.com


http://www.jblproservice.com/pdf/Network%20Schematics/3145%20Network.pdf

chokes

5.4 mh dcr 0.5 ohms
4.8 mh dcr unknown (or as above)
1.8 mh dcr unknown

Notes
JBL used iron core chokes to miniimise losses here but you can use air core which in theory are better but more costly. The 5.4 mh chokes JBL used had a dcr of 0.5 ohms for production reasons, you can shoot for a lower dcr but some retuning of the 2245 ports may be required according to Greg Timbers.

In my crossover the tapped chokes were not used (as they are unavailable to the best of my knowledge) and an alternative consisting of split air core chokes provides equivelant voltage drive. (courtesy of Giskard/GT)

0.68 mh/ 0.32 mh HF section

0.122 / 0.05 mh UHF section

I wound these values by trimming commercial standard values with an LCR meter. I am happy to provide these chokes for a small fee if you are unable to arrange this.

I will post a pdf of the equivelant circuit for the HF and UHF section shorlty. (Note the 0.24 hm choke is not used in the equivelant design)

I had the large chokes made to order, if you live in Australia Voller Transformers are excellent, if you are in the USA try Parts Express , SpeakerCity, Zalytron and others on www and if you are in Europe try Mundorf.

Capacitors.

This has to be the most debated area of DIY Audio. I will avoid any discuss as I am sure you will have fun tweaking the sound to your liking.

90 uf 250 VDC*
60 uf 250 VDC*
20 uf 250 VDC*
14 uf 250 VDC*
8 uf 100 VDC#
3 uf 100 VDC#
12 uf 100 VDC#
1.5uf 100 VDC#
1.0uf 100 DVC#

*I used metalised polypropolyene non polorised capacitors here, sourced from AOEN, bypassed with 0.1 uf film foil AEON.
# These are all Hovlands speaker capacitors.

#I highly recommend pure film and foil varieties in this design. They are expensive but the results show. Try PartsConnexion, Handmade Electronics, Welbourne Labs and the diy speaker supplier mentioned above.

You can of course use metalised polypropolyene or mylar and bypass with small film foils capacitors. JBL did this in the original design. I recommend North Creek Audio as a supplier for this approach.

Resisters

25 ohm 10 watt
5.1/5.1 ohm 10 watt
39/39 ohm 10 watt
62/62/62 ohm 10 watt
20 ohm 20 watt
39/39 ohm 10 watt

I recommend Mills power resisters here, the ceramic resisters and usable but they are very fragile.

The pads are all ( 3 ) x 8 ohm 50 watt, they can be sourced from Parts Express.

The layout I used was done with Tag Stripes and point to point, not on a PCB. I will post this when time permits

Ian

Claus K
03-14-2004, 02:45 AM
Hi Ian,

can you tell us how the split of these inductors is. I mean would the smaller inductors form the bottom or on the top half sections?

Another idea I have is instead of using split inductors to use normal inductors of the full value (e.g. 1mH for the HF part) and then carefully unwind them measuring remaining inductance until youve reached the required "split point", then scratch off some of the wire isolation and solder a "tap" wire onto the inductor wire. Then rewind the wire that you wound off again. Basically you would end up with a kind of DYI tapped inductor.

Using two separate inductors as you suggest will give the same voltage drive but with a higher source impedance and Im pretty sure that this will change the crossover characteristics (mabe the change is small enough though).

Ian Mackenzie
03-14-2004, 03:39 AM
I did not model the equivelant on Spice, but can assure its measures precisely.

Ian

Ian Mackenzie
03-14-2004, 03:40 AM
The HF network

Ian

Ian Mackenzie
03-14-2004, 03:45 AM
The layout....I just followed the schematic

Ian

Ian Mackenzie
03-14-2004, 09:24 PM
Please refer to this thread 4345 Monitor plans for full visual exterior dimensions...courtesy of Bo.

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&postid=17518#post17518

Ian Mackenzie
03-15-2004, 04:15 AM
Here is a simplified drawing showing the side elevation.

I have omitted the interior details for clarity so don't panic.

From theses basic drawings we can derive basic panel sizes and router cut outs and rebates.

Ian

Edit Note: I just realised there is a bit of an assembly issue this this drawing. Guess what is it? I will re draw this diagram tonight.

To make clamping the top , bottom and sides together easier I have re arranged the side joint so the top and bottom rebate into the sides. This way shorter and no doubt more accessable bar clamps can be used.

Ian Mackenzie
03-15-2004, 04:31 AM
Here is a precision drawing of the front edge moulding courtesy of Bo and Widget. Probably done over a few bottles of Red ..LOL

Ian

Ian Mackenzie
03-17-2004, 12:09 AM
Here is the front view of the simplified plan.

I realise this may all seem obvious but clarity is important particularly when you have rebated joints.

Ian

Ian Mackenzie
03-17-2004, 12:42 AM
Here is the final simplied drawing.

Once I have proofed the drawings I will make a procurement list of all the panel sizes and then post detailed drawings of the panel router rebates.

I will also post more detailed drawings of the bracing and internal midrange sub enclosure shortly.

Ian

Ian Mackenzie
04-08-2004, 02:42 PM
Sorry for the delay in completing the drawings but my time has been diverted to other priorities.

I will post and complete the drawings over the Easter long weekend...

Ian:eek:

subwoof
04-08-2004, 03:22 PM
2000 is a BIG number of postings for one thread...:o)

But it's a rabbeted joint, not rebated.

BTW, for any of the east coast guys who are contemplating this, I will be building a pair in the woodshop in about 6-8 weeks and could always make more....

But of course *after* I see ian's dwgs in person over some "local" ales....

:cheers:

sub

Ian Mackenzie
04-09-2004, 02:35 AM
You mean Views man....too many ales after Sunday school sounds likes.........to me

I may have to make me some concentrated solution and bring it with me ......I'd hate to miss out on my Vitamins..particularly Iron.

If we distilled down a dozen gallons a Yankee ale...that might help...at least avoid wetting the bed........LOL:eek:

More soon:rockon1:

Ian

Ian Mackenzie
04-10-2004, 03:27 AM
Okay you guys.....

Time for a disclaimer....."I take no responsibility for errors or omissons to any drawings or dimensions posted thereon in thread."

These drawings are a guide to assembly of the 4344 enclosure, no doubt many of you will add your own twist to how you wish to build them.

Now for some panel dimensions..

Top and bottom 24 x 14 3/4 inches (panel thickness = 1 inch)

Sides 41 3/8 x 14 3/4 inches (panel thickness = 1 inch)

Front and rear 39 7/8 x 23 1/2 (panel thickness = 1 inch)

So from here you can talk to your favourite lumber yard about sheet sizes for your project.


The next step is to think about the detail of each panel. This will include router cuts and dowel joints to hold your box together!

I'll save that for a strong coffee in the morning

Ian

Ps Tomorrow is officially JBL Blue Day

Ian Mackenzie
04-10-2004, 06:20 PM
Here is yet another drawing,

This time details of the joints, note there Router cut 1/2 x 1 inch but this is only in the sides for the top and sides to join, the top and bottom extend by 1/2 inch into the sides.

This is also another Router cut this time in the top, bottom and sides 1/4 inch in parrellel to the front face 1 inch wide and 1/4 inch deep. The front baffle will therefore need to be fitted during assembly of the top, bottom and sides.

The rear panel has an identical Router cut, but is not set in from the rear panel face and if your cutting is accurate you will be able to fit the rear baffle last after final enclosure assembly.

All the joints should be liberally glued with your favourite PVA wood glue and then clamped securely overnight. Then as suggested Subwoofer, drill holes for 1/4 inch dowells evenly space into each side joint for added strength.

Ian

Ian

Ian Mackenzie
04-10-2004, 06:48 PM
Here I have added the bracing to the side elevation, 1 x 2-3 inch of hardwood.

These stiffeners should be cut for a firm fit so they butt up against the adjacement panel then be liberally glued and screwed into place.

Ian

Ian Mackenzie
04-10-2004, 07:26 PM
This front view has the bracing also added.

Note the additional 1 x 1 cleats used for fastening the removeable rear panel.

I used this approach in my diy 4345, it works quite well.

Again all these stiffeners should be glued and srewed with a snug fit to the adjacent panels.

The cabinet when fitted with these stiffeners is a solid as pressure vessel.

Ian:smthsail:

Ian Mackenzie
04-10-2004, 07:34 PM
Tomorrow I'll post the remaining drawings detailing the 2122 Dog Box.......Time for a Guinness and some JBL "BLUE"

I have it on good authority these 4313's are good for colour matching...LOL

Ian Mackenzie
04-22-2004, 04:16 AM
Okay,

Here are some images of my 4345 cabinets with the authentic JBL Blue baffles.

Special thanks to Bo for so kindly assisting with the sourcing and colour matching, a difficult job and a fantastic result.

If we had an award for the most well liked and most generous Lansing Heritage Forum member, Bo would be the recipent.

The look in reality is quite impressive and I am sure they sound even sweeter. (no kidding).

Ian

Robh3606
04-29-2004, 04:12 PM
Hello Ian

They look great!! I was messing with Paint Shop to make me some labels for my 4344's and it was fun!! Used your dimensions for spacing. They aren't perfect but it will save someone else the trouble in they want to use them.

Rob:)

Robh3606
04-29-2004, 05:48 PM
Just for fun

Rob:)

Hofmannhp
04-30-2004, 01:26 AM
Originally posted by Robh3606
Hello Ian
They look great!! I was messing with Paint Shop to make me some labels for my 4344's and it was fun!! Used your dimensions for spacing. They aren't perfect but it will save someone else the trouble in they want to use them. Rob:)

Hi Rob,

if I understand you right, you made some labels for the 4344?
Can you please tell me more 'bout this. Material, silk screen printing? input file (graphics)? does the pic show an original or the DIY version?
Need some labels for 4333b (L-pad and grille)

HP

Robh3606
04-30-2004, 07:28 AM
Hello HP

What I did was start from scratch in Paint. Just set-up you scale. I use 100 pixels per inch. So if I want a 3x9 tag I draw a 300X900 box. For higher resolution use 200. You could also do a high res scan on any tag for the logo and modify accordingly. Then I take a real tag or a photo of the tag and use that for scale, font matching and colors. Bos tags are where I got the colors from and a posted 4344 is what I used to copy. The tag on the speaker is home made with Paint Shop. It was printed 1 to 1 on 360 Inkjet paper, cut out and applied with rubber cement which wont dissolve the Ink. On the real deal I will print in high resolution mode with better media. I have used the matt clear plastic overhead sheets. Just print an inverse image. That way you have a mat plastic tag that is very rugged. Use rubber cement to apply. This is a very simple and inexpensive way to make yourself a decent copy of the L-pad tag. The grille could be made to work.

Rob:)

4313B
04-30-2004, 08:06 AM
Hmmm, do you guys want to start a thread with scanned foilcals? I don't have any of the large Studio Monitors anymore (except the 4430) but I might have some L212, 4313, L96, L100, and L112 foilcals around.

Robh3606
04-30-2004, 09:10 AM
Hello Giskard

Sounds like a good idea to me. Would make it easier if we had a library of scans to use outright or as a base to generate the required label.

Rob:)

Guido
04-30-2004, 02:08 PM
If anyone needs foilcals I might be able to help.

See
http://www.audioheritage.org/vbulletin/showthread.php?s=&threadid=1005&highlight=4425+DIY
for an example.

The foilcals are selfmade

Robh3606
05-05-2004, 06:11 PM
Cut my MDF for the cabinets today. I hope to have them built in the next 2 weeks. I have been planning these for almost 6 months now so it was a big day to actually start. They are big suckers!! Had to modify the dimensions a bit for them to fit into my existing set-up but I don't think the changes will really affect anything as the volume will be very close. I was going to try something really different cabinet wise but decided against it. I just don't have the room. The cabinets are straight up 3/4 mdf glued and screwed with 2x3 and 1x2 braces like my mains now. Nothing fancy.

Rob :)

Robh3606
05-11-2004, 07:23 PM
Have all the holes cut. Have to get a Sonotube and I am ready to rip! Had to layout the drivers. Feel like a kid at Christmas:bouncy:

Rob :)

4313B
05-11-2004, 07:28 PM
Cool Rob!!! :)

boputnam
05-11-2004, 07:39 PM
Rob...

Them are gorgeous! Well done - nearly... Maybe get that damned Aussie to assist in the final assembly, hey?

And, if you want some of the CORRECT JBL Blue, send me a pm - you can have the tin I was holding for Ian's return to Oz... ;)

Ken Pachkowsky
05-11-2004, 09:20 PM
Gonna be nice Rob, Congrats!

Hofmannhp
05-11-2004, 11:17 PM
Originally posted by Giskard
Hmmm, do you guys want to start a thread with scanned foilcals? I don't have any of the large Studio Monitors anymore (except the 4430) but I might have some L212, 4313, L96, L100, and L112 foilcals around.

Hi Giskard,

yesterday I went through the JBL spare part list.
Am I right, that not all of the listed parts are available?
There are also some foilcals listed.
i.e. foilcals of drivers.......from obsolete models.....

HP

4313B
05-12-2004, 04:06 AM
Originally posted by Hofmannhp
Hi Giskard,

yesterday I went through the JBL spare part list.
Am I right, that not all of the listed parts are available?
There are also some foilcals listed.
i.e. foilcals of drivers.......from obsolete models.....

HP The JBL Pro miscellaneous parts list is out of date despite the date stamp. I believe JBL has three 4333B foilcals left. All the others are NLA.

Robh3606
05-12-2004, 05:07 AM
Thanks

I will drop some more pictures up as they go together. With any luck I might get a workable set-up before Ian gets here:D Bo let you know on the blue.

Rob:)

4313B
05-12-2004, 05:27 AM
"Had to layout the drivers. Feel like a kid at Christmas."

Uh-oh... I'm feeling the pull... :eek:

Let's see, all I need is yet another pair of 2405's... :hmm:

Hofmannhp
05-12-2004, 06:47 AM
Originally posted by Giskard
...... I believe JBL has three 4333B foilcals left. ....

Giskard,
very interested in two of them. Pls let me know how we can handle this.
HP

Ian Mackenzie
05-12-2004, 06:52 AM
Hey Rob,

Nice driver suite,

I have the 3145 networks in my luggage for you to try out, but don't rush the box.

Ian

boputnam
05-12-2004, 07:00 AM
Originally posted by Ian Mackenzie
I have the 3145 networks in my luggage for you Yea, and he slept on 'em the entire time here!! Damned Aussie... :bash:

Ian Mackenzie
05-12-2004, 07:49 AM
Well I did offer you the opportunity but as you said only under parental supervision.

Ian

boputnam
05-12-2004, 07:54 AM
Originally posted by Ian Mackenzie
..only under parental supervision. Yea, too bad we couldn't find one...

Ian Mackenzie
05-12-2004, 07:54 AM
Had a close up and personal look at John's 4343's last night, NICE.

The quality of the cabinets was as Bo's 4345s. Much nicer than the 4435's IMHO. Just the veneer and polish appears better.

We also sucked the juice on the 4435/4343 comparsions, still thinking about that one.

Its a case of preferences and depends on the type of genre/program material.

More later.

Ian

boputnam
05-12-2004, 07:55 AM
Originally posted by Ian Mackenzie
Well I did offer you the opportunity... Plus, you'd made 'em for Robh, fer crissake - no way I'm 'bout to steal from a Forumite! :no:

Ian Mackenzie
05-12-2004, 07:56 AM
So Suz must have been out.

Still you are have been crowned the Harp artisan and King of knob Farming.


Ian

Ian Mackenzie
05-12-2004, 08:17 AM
Ah,

Come on, the idea was for all you Lansing Formites to try some sweet candy.

I might even go fully biamp having taste tested Passlabs red wine with the lovely Karen.

And having heard John's 4343 play so nicely, I think the amps up stream also make big influence.

Those Mack's really are as good as it gets, very engaging and not at all clinical.

Yeah know I am going off topic....Blah Blah.

Talk to you guys later, we're going for a drive.

Ian:smthsail:

Robh3606
05-16-2004, 09:17 PM
Finally have useable cabinets to load drivers into. Forgot how much goes into them. Set them up as 5Cu. Ft. subtracting the midrange enclosure and ports. Figure the glass will cover bracing and the horn. Tunned them to 30 Hz with dual 3" ports.

Rob:)

Robh3606
05-16-2004, 09:18 PM
Another about to glue and nail the back.

Robh3606
05-16-2004, 09:22 PM
Final with the back panels on the the top braces installed. Just have to decide how to finish the MDF??

Rob:)

Robh3606
05-18-2004, 07:44 PM
One loaded up waiting for a first listen!:rockon1:


Rob:bouncy:

boputnam
05-18-2004, 08:31 PM
Originally posted by Robh3606
One loaded up waiting for a first listen!:rockon1: Very, VERY nice work, Rob! Ensure you don't rush into a tastetest without proper EQ. Four-ways are notoriously difficult to tame, and are hugely benefitted by proper EQ. You won't know what you've got 'till you get 'em set-up proper... :yes:

I just re-Q'd the 4345's tonight, and my-oh-my, somebody's knees must've been knocking the EQ in the pantry... :banghead: Subtle - VERY subtle - movement to the 1/3 octave has audible influences. Back-on goes the security screen...

boputnam
05-18-2004, 08:45 PM
Almost forgot - when the damned Aussie get's there he can walk-you through the Transfer Function mode of SmaartLIVE - at least how he saw it employed both at the home, and at the gig.

The benefit is, even during and using a live mix, Transfer Function enables ensuring flat EQ. Another-words, you don't need to bore the audience with Pink Noise, nor are you stifled during the gig to being unable to know what is going-on acoustically. ANY reference material can be used, and if properly time-delayed (for mic distance from speakers) can provide an astonishingly powerful real-time tool to analyze room acoustics.

oldmics harped on this way-back when. Most folks use SmaartLIVE only in RTA mode (oh-so lame). Even when Little Wheels Band are last-up, I get the laptop going, and using the Transfer mode, re-Q the room on the fly, to great result. Our audience is noticing the difference...

Sorry - enough outa me... :slink:

Robh3606
05-18-2004, 08:58 PM
Thanks Bo

With Smart Live can you configure your windows mixer Mic Input as a channel?? I have put off loading the trial software so I can have the most productive time with it. I have a phantom power box for my measurement mic but no mic preamp unless I use an input to an old casette deck as my preamp and just monitor that as a second channel. Can you do it with just the sound card???

Rob:)

boputnam
05-18-2004, 09:18 PM
It depends... :hmm:

Your sound card must be full duplex, and have stereo inputs. My laptop failed that test, requiring I go through three different USB preamps to find one that worked (with my laptop). My laptop had some "issues" with the SmaartLIVE drivers - particularly with a Delta Audio USB device otherwise well regarded. I could not sort-out the problem, and had to upgrade to the "USB Pre" - a phenomenal (but pricy...) device that has two XLR mic inputs (with gain control), and numerous other flexibility. The USB Pre is co-sold on the SIA site for an otherwise un-matched price, but is, as I say, still pricy. Were I not using it twice a month live (and frequent tweaking our rehearsal studio), it would have been hard to justify.

You must be able to:

1) input the Pink Noise into the preamp (output from SmaartLIVE).
2) pre the EQ, sample the pre-amp output (whether Pink Noise or other material) - this is the reference signal. I usually grab it from either a "Y" off pre-amp output, or use the EQ parallel input as a source...
3) sample the ambient output of the speaker (one side at a time) of whatever source you are using (use a flat-response acoustic mic)
4) measure the variance between the reference signal and the ambient mic, and adjust the EQ for flat.

Hmm-mm-good... :yes:

Robh3606
05-18-2004, 09:32 PM
Thanks Bo

I will have to give it a whirl and get back to you. My card is full duplex with stereo inputs so it should work.

Rob:)

Hofmannhp
05-18-2004, 11:55 PM
Originally posted by Robh3606
Thanks Bo
With Smart Live can you configure your windows mixer Mic Input as a channel?? I have put off loading the trial software so I can have the most productive time with it. I have a phantom power box for my measurement mic but no mic preamp unless I use an input to an old casette deck as my preamp and just monitor that as a second channel. Can you do it with just the sound card???
Rob:)

Rob and Bo,

I arrived exactly at the same point as Rob.
The problem is:
Connection of the very linear measurement mic to the PC system.
I tried it first with the soundcard mic input ...-> very poor.
After building a phantom power source for the balanced mic out, I tried some prof mic amps (V676a) but there the frequ resp. is also cutted near 35Hz and 15kHz.
Now I decided, to develop a special mic preamp with the best parts available for less noise and max linearity.
The magic part is a matched transistor pair called LM 394.
My benchmark here is min 90dB S/N with + 34dBgain and a linear frequency response from 5Hz to 40KHz.
If you use any of the equipment like cassette deck or.... as a mic preamp, the main frequency response between 18 and 50Hz is only a trend.
If there's any interrest in such a mic preamp (when ready and tested) let me know.
HP

boputnam
05-19-2004, 06:40 AM
HansPeter...

You sir, are quite correct. I found that using the laptop on-board sound card gave poor results. And, in-fact the best laptop soundcard is pathetic quality, unable to do what is needed. Some PC cards are plenty good, and capable, but I needed remote capability.

Sound Devices' USBPre (http://www.usbpre.com/) - the merits of which I've posted before - was my final solution after two other devices failed to give the flexibilty and/or had driver conflicts. All-in-all, I'm really glad everything else failed, because the USBPre has proven perfectly designed for the SmaartLIVE Transfer function application (and RTA, as well), in-that it gives you gain control over both the reference and measurement signals to ensure your measurements (and adjustments) are relevant and accurate.

Robh3606
05-19-2004, 07:18 AM
Don't load new software after 11pm. I was playing until about 2:30 last night before I realized the time. It works just fine with my soundcard and measurement mic. Very powerful sofware. Spent a hour doing sine sweeps in 1/12 octave monitoring SPL looking for room modes. Very educational also confirms my Behringer the two are damn near exact is 1/3 octave RTA mode. Have to play more. Thanks Bo for the help.

Rob:)

boputnam
05-19-2004, 08:01 PM
Rob...

I've been thinking about your post - in-particular tonight listening to the fruits of my re-EQ last night.

These four-way studio monitors are tricky. They certainly can be set-up to great satisfaction vis-a-vis comparisons to "ordinary" (not meant in a demeaning way...) cabinets. It will amaze your friends. However, there is some astonishing JBL engineering evident when these are EQ'd proper. Investing in accurate and suitable test-gear seems a "must" if one is to tame a four-way to the acoustic response of the room they're in, and really hear what they are capable of. Period.

I loved the 4345's the first time I heard them. Today, I marvel ever-more at their definition, clarity, voicing, and depth of soundstage - characteristics that are optimized by test-gear equal to the quality of the 4345's, and up for the challenge.

Do not under-invest in your test gear, even if only used a few times a year.

'nuff said...

Ken Pachkowsky
05-19-2004, 08:13 PM
Hmmm......Loved them the first time I heard them. Now they sound better.....hmmmmm.:rotfl:

Could not resist BoBo

boputnam
05-19-2004, 08:51 PM
Originally posted by Ken Pachkowsky
Now they sound better... Not quite, my audio-addicted friend... "Today, I marvel ever-more..." is/was the phrase, and you know better than I how important is the set-up. :yes:

Why, by now, you must have had to elevate the bed to stuff all your test gear beneath!! :nutz:

4313B
05-20-2004, 07:32 AM
"However, there is some astonishing JBL engineering evident when these are EQ'd proper. Investing in accurate and suitable test-gear seems a "must" if one is to tame a four-way to the acoustic response of the room they're in, and really hear what they are capable of. Period."

We've talked about this in several versions of the forum and I don't think it can be stressed enough. "Understanding what you are dealing with." It's printed in several JBL publications.

I can't count the number of people who've maligned JBL Studio Monitors over the years. Every single one of them tried to use a 43xx in their home. They were all plug and play types with virtually no concept of the kind of loudspeakers they were dealing with. Their negative experiences were directly related to their attitudes that if they expended the extra effort to spend x amount of dollars on a JBL Studio Monitor then it should just shake right out of the shipping carton and kick major ass. Never mind that many of their rooms utterly sucked in the acoustics department.

It isn't just the 4-ways, the 3-ways and 2-ways like special consideration too. Systems like the 4331 and 4333 can sound very, very good. They can also sound downright awful. It's the user's choice as to how much effort they want to put into the end result. The Studio Monitor should be one of the tools in the bag, not the only tool in the bag.

boputnam
05-20-2004, 08:06 AM
Originally posted by Giskard
"However, there is some astonishing JBL engineering evident when these are EQ'd proper. Investing in accurate and suitable test-gear seems a "must" if one is to tame a four-way to the acoustic response of the room they're in, and really hear what they are capable of. Period."

We've talked about this in several versions of the forum and I don't think it can be stressed enough. "Understanding what you are dealing with." It's printed in several JBL publications.

I can't count the number of people who've maligned JBL Studio Monitors over the years. Every single one of them tried to use a 43xx in their home. They were all plug and play types with virtually no concept of the kind of loudspeakers they were dealing with. Their negative experiences were directly related to their attitudes that if they expended the extra effort to spend x amount of dollars on a JBL Studio Monitor then it should just shake right out of the shipping carton and kick major ass. Never mind that many of their rooms utterly sucked in the acoustics department.

It isn't just the 4-ways, the 3-ways and 2-ways like special consideration too. Systems like the 4331 and 4333 can sound very, very good. They can also sound downright awful. It's the user's choice as to how much effort they want to put into the end result. The Studio Monitor should be one of the tools in the bag, not the only tool in the bag.

A beauty post, Giskard. Reminds of the set-ups I've seen/heard of 4-way Studio Monitors, running passive, and plugged into a Receiver... :banghead: Oh well, when they tire of them, maybe they'll show-up on eBay... :yes: :yes: :yes:

boputnam
05-20-2004, 08:19 AM
All gear has "coloration". The amount and influence of that on the acoustic response simply cannot be guessed at.

Scotty Fitlin's having a (justified...) love affair with the Crest amps he's lately been installing at his larger-than-life application. Fine, but, I'm quietly curious on just how much do we really know: How much testing / measurement has been done? Were both the prior set-up and the current one EQ-optimized so that the improvement can really be attributed solely to the Crests? Sure, the ears know, but are the impressions borne-out by giving equal chance to any gear that is trialed? Maybe the Crest have a coloration that is more pleasing to Scotty in his set-up - maybe the same could have been achieved with a better controlling of the existing (now prior...) equipment. I don't know. There has not been much posted on how the application was being "tested"/measured.

I do know that the more I'm able to quantitatively measure and thereby control the signal, the more depth (qualitative pleasure) I get from all my gear, and the more I appreciate the capability that often lies unutilized in stuff I've got. (whew! actually back on topic... :rotfl: )

Having said all that, oldmics has a cotton for Crests, and he more than many of us get's to put gear through the paces, in a variety of settings. So, off I go then... :slink:

Robh3606
05-20-2004, 09:11 AM
Plug and play??? :scold:


Rob:)

Ian Mackenzie
05-20-2004, 11:49 PM
I've been thinking about your post - in-particular tonight listening to the fruits of my re-EQ last night.


I loved the 4345's the first time I heard them. Today, I marvel ever-more at their definition, clarity, voicing, and depth of soundstage - characteristics that are optimized by test-gear equal to the quality of the 4345's, and up for the challenge.

Do not under-invest in your test gear, even if only used a few times a year.

'nuff said...

Hey dood, every try getting your ears Waxed, best EQ your ever likey to hear..no Kidding. Shave 1/2 a db off hear and there and WOW.

Hey, on the topic now, Did some interesting observations with John Nebel. We found using the 2235's on the 4343 meant that the levels in the bi amp mode for the woofers extra 1 db sensitivity had to be compensated.

Without allowing for this the mids sounded withdrawn, particularly in straight comparion to the 4435's. With the adjusted sensitivity the voicing of both systems was very similar.

I find similar adjustment, often 1/2 a db on the pads can make or break the whole package, I doubt if the RTA would pick that up.

These types of adjustments take a long time as Robert just commented.

By the way Robert has a very sweet sound on his 2344 / 2123 hyprid.

Ian

Ken Pachkowsky
05-21-2004, 12:05 AM
Originally posted by Giskard

It isn't just the 4-ways, the 3-ways and 2-ways like special consideration too. Systems like the 4331 and 4333 can sound very, very good. They can also sound downright awful. It's the user's choice as to how much effort they want to put into the end result. The Studio Monitor should be one of the tools in the bag, not the only tool in the bag.

I spent last Sunday EQ'ing a room for a buddy who had purchased a nice little JBL 3 way system. I convinced him to get a 1/3 ocatve EQ and even I was amazed at the difference it made on those 4313B's.

4313B
05-21-2004, 06:38 AM
"Did some interesting observations with John Nebel. We found using the 2235's on the 4343 meant that the levels in the bi amp mode for the woofers extra 1 db sensitivity had to be compensated."

Now that is kind of weird. The 2231 is the more efficient driver but not by a terrible amount. It would be interesting to run a response curve of both drivers side by side to see what they were doing at the crossover frequency. It might be that one has a slight peak or dip that the other lacks. Anyway, if you did the deed and they sound better for it who's to argue.

Ian Mackenzie
05-28-2004, 08:44 PM
Hi,

Just just looked in BassBox and the stats in there are indeed similar. Oh well the audibility of the issue is certainly real, just the sensitivity was the only thing I could think of at the time to explain it.

Regards Johns Nebel's equation, the other option is to raise the 2122H a notch and the horn and slot in equal incriments.

I just think that when we start comparing models that the "0" positions on the Pads do not necessarily mean "flat" in a particular room and some adjustment of the pads is mandatory for the sweetest balance of lows, mids and hi's.

The 4435 also have the flat power response unlike the 4343 so that blows equivelant pad settings to hell.

Anyways I felt privileged to hear Mint 4343 and 4435's side by side.....a JBL wall of sound..WOW

Ian

Hofmannhp
06-27-2004, 12:46 PM
Originally posted by Ian Mackenzie
Under Construction

This thread will be dedicated to those members wishing to construct the vintage JBL 4345/4344 Professional Series Studio Monitors.

Over the next few weeks I will document blue prints (in JBL Blue..LOL) and provide a Step by Step Guide to Enclosure and Crossover Network Design & Construction.
......Ian Mackenzie.
:cool:

Ian,

sorry....saw this posting today......let me know if I can assist you in this job (I don't wanna disturb your circles with YOUR documents)

HP

PS: thanks for the drawings....I will wait for your reply

Ian Mackenzie
06-27-2004, 02:53 PM
Well it does need completing but the interest died off when I made the great voyage to North America in search of the Pass and the Diva.

Now that I have returned and washed my soiled denim from La Honda I will complete the journey here soon enough. Perhaps we should purge this work with the JBL Blue Thread (The Bermuda Triangle) before it gets covered in more graffitti.

Ian

Robh3606
07-05-2004, 06:40 PM
Hello Ian

Will have these babies up and running by the weekend. Some odds and ends like wiring in your crossovers. But the cabinets are done and the driver loaded. Let you know how I like them.

Rob:)

Ian Mackenzie
07-05-2004, 10:35 PM
Very nice Robert!

:cheers:

Ian

Ian Mackenzie
07-23-2004, 09:15 PM
here are some near field response measurements some of you might find interesting and useful.

All measurements are taken with the drivers on the 4345 baffle with the crossover filters inserted. I did this to create a library of data for when I try to quad amp the system.


This is the 2122 right channel

Ian

Ian Mackenzie
07-23-2004, 09:20 PM
The 2122 left channel.

The near field distance is about 1 foot. (30 cm)

Ian

Ian Mackenzie
07-23-2004, 09:38 PM
The right channel 2307/2308 horn lense combination.

Ian

Ian Mackenzie
07-23-2004, 09:41 PM
The left 2307/2308 horn lense combination

Ian

Ian Mackenzie
07-23-2004, 09:44 PM
The 2405 slot right channel.

Ian

Ian Mackenzie
07-23-2004, 09:47 PM
The 2405 left channel.

Ian

Ian Mackenzie
07-23-2004, 09:53 PM
Here is an updated 2307/2308 response measurement. The 2308 has 4 mm of soft open cell foam packed in the rear of the lense.

I have not done any subjective comparisons yet.

Ian

Ian Mackenzie
07-25-2004, 03:17 AM
Here is the full system response at 1.5 metres, gated to minimise room effects. I a reflection free field environment I would expect this to be marginally smoother.

The response about 15 kherts is down a bit, perhaps my 2405 need a some more joules! I plan to have all the compression driivers re gaussed soon.

Ian

boputnam
07-25-2004, 03:05 PM
Nice.

Remind us about your measurement microphone - Panasonic, wasn't it? :hmm:

Ian Mackenzie
07-25-2004, 05:39 PM
Its the Panasonic.

Technique matters as much as anything. I am research this and will post some information in a day or two.

Bit like a surveyers or navigators instrument, in the wrong hands and your stuffed.

Ian

Ian Mackenzie
07-28-2004, 05:36 AM
Here is another graph,

Some explanation is in order.

Over the past few weeks I have been evaluating the 4344mk11 network to assess if its horn and slot passband filters would work for the 4345, saves the split chokes.

All the above graphs used the original 3145 mid passband filters, but the 4344mk11 horn and slot passband filter topologies.

There are some differences but its works well enough. (namely in the UHF passband.) So if you are stuck for the split chokes you can use the values shown in the 4344mk11 network for the horn and slot including the fixed resistor Pads.

However, tonight I returned to the original 3145 network (4345 original network) and experiemented with chokes of various Dcr. The design is reasonably tolerant of choke Dcr, but try and keep it as close to spec as possible, (JBL works to 5% tolerance).

The graph below represents what I consider the state of art crossover for this system (3145 with Giskard/GT alternative split choke values).

The response is on axis at 2 metres indoors and is unsmoothed, not even 1/3 octave smoothing. The divisions are 6 db, the scale is linear and not log so there is more detail at high frequencies and less at low. (The JBL graphs have a log scale).

In comparison to GT's test data, under the microscope the similarity is remarkable and the transitions are perfect.

Adjustment of the pads can fine tune the balance overall and that is up to the user.

Ian

Ian Mackenzie
07-28-2004, 05:52 AM
This is the 2405 slot run at near field (30 cm), the divisions are 6 db linear scale as above.

Ian

Ian Mackenzie
07-28-2004, 05:55 AM
The 2307 horn response with the 2425 diaphrapm (with 2308 lense ) as per above measurement conditons.

Ian

Ian Mackenzie
07-28-2004, 06:05 AM
Here, the 2122H midrange near field response.

Ian

Ian Mackenzie
07-28-2004, 07:18 AM
So there you have it, a complete set of graphs for the diy JBL 4345.

If you are planning to build either the 4345 or 4344 I am happy to assist.

Ian

Ian Mackenzie
07-29-2004, 11:04 PM
Having a JBL day off (home with the flu) I have quietly developed some techniques for tweaking the response for ruler flatness.

Previous mid field response measurements drew to much interference even with tight time gating.

So I began carefully measuring and documenting the exact near field response levels for the mid, horn and slot against the zero marker on the Foil cal for the midrange driver (2122H).(referenced (-3) db from maximum.

I was able to then adjust the pads on the horn and slot for each to be level with the zero line on the response output.

As it turns out, adding a 20 ohm shunt resister across the horn cpmpressio driver (8 ohm driver) terminals shaved a db or two off its sensitivity and when its pad is at the zero position this is now correct.

Below is an overall full response taken near field mid way on axis between the horn and slot so as to provide the best overall mean response. The mid cones dispersion is sufficiently wide that its sensitivity is only slightly down.

The response is now very smooth and even overall. So its can be seen that with even modest test equipment good results can be obtained with the right approach.

The ultimate test is however listening, and I will do that later over a few ales. (after I have calibrated the other monitor)

Ian

Ian Mackenzie
07-30-2004, 08:58 AM
The subjective performance mirrors the response measurements above.

After trying several different pad levels for the Mid, High and Uhf I settled for zero (0) for the UHF, zero (0) for the HF and (-1) for the midrange.

The latter is most likely the result of an anomally with my ealier measurements but non the less the response envelope did not lock in correctly without a slight reduction in the midband level.

The drivers now behave as one, and their individual outputs are indistinguishable at the listening position.

Setting the UHF at +1 and the HF at -1 while maintaining the above mid level is altenative alignment of the Pads . This give a sort of BBC (reserved) dip in the upper midrange with a nice crisp top end. But I prefer the former setting for the classic JBL presentation.

The Foil Cal is now calibrated from -3 to +3 for each driver Pad so adjustment can be made with some degree of accuracy based on the actual acoustic response of each driver.

If you are planning to build the 4344 monitor with the 2235 woofer using a full passive crossover network it should be noted that the above references for adjustment levels of the Foil Cal relate to the 2245 woofer sensitivity of 95 db 1 watt @ 1 metre.

So the zero level positions for midrange on the 4345 are (-3) db from maximum, and (-4) db for the HF and UHF.

For the 4344 the pads levels will need to be referenced to the sensitivity of the 2235 woofer which is 93 db 1 watt @ 1 metre.

Therefore, the zero level positions for midrange on the 4344 are (-5) db from maximum, and (-6) db for the HF and UHF.

(This assumes you plan to use low loss inductors as specified by JBL)

The point of providing the above detail on the acoustic alignment of the system is that without a reasonable degee of calibration it is nearly impossible to setup the system correctly. So to avoid dissapointment and frustration some care must be taken to calibrate the level pads.

Ian

Ian Mackenzie
07-30-2004, 09:06 PM
I have just reviewed the thread and noted that we have not looked at the Dog Box dimensions or its position on the front baffle.

Some of you may wish to adapt these drawings to suit your own interpretation of the driver layout so they are for here for reference.

The Dog box internal measurements are 10 x 6 x 14 1/2 inches, the internal volume is 1/2 cubic ft3. The Mdf walls are 3/4 inches. Similar construction methods can be used from the main enclosure.

I have chosen to align the Dog Box with the edge of Foil Cal position for drawing purposes. Again you may wish to vary the dimensions somewhat or even flush mount one side to the main enclosure.

The Dog Box should be securely fastened to the front baffle with PVA glue and screws once you are happy with postion.

The thickness of the side wall bracing will also need to be consider or moved to allow clearance of the Dog Box.

Ian

Alex Lancaster
07-31-2004, 11:58 AM
The bad news "Messenger" always got shot, and while We are at it, You Merciless pagans, throw a few prayers for Charlie Rummel, it works.

Ian Mackenzie
07-31-2004, 06:38 PM
There's above 5000 views on this thread now although not many posts from interested members.

If there's sufficient interest I'll start posting the 4345 drawings during the next week or so.

Ian

andresohc
07-31-2004, 08:00 PM
If there's sufficient interest I'll start posting the 4345 drawings during the next week or so


yeah, yeah, yeah, yeah, yeah!

Figge
08-01-2004, 02:09 AM
Originally posted by Ian Mackenzie
If there's sufficient interest I'll start posting the 4345 drawings during the next week or so



:yes:

andresohc
08-01-2004, 07:00 PM
I will be building the 4345 system in the next three to four months (hopefully). I have collected all the parts (minus the crossover stuff yet), and have been waiting to see the cabinet blueprints/ info. I have bought the mdf, the jigs, router guides bits, glue, mahogany veneer. I have printed this thread and the others (as best I could in that the borders are too wide) and reread them several times. I am waiting a while to start the project, but am also anxiously anticipating the blue prints. Please dont mistake lack of response to threads as lack of interest. Basically I dont have much to contribute, but try to absorb as much as I can. When the chips start flying I am sure I will have some educated questions. I greatly appreciate all the documentation you have provided allready and thank you for the committment to get this stuff out. I can reverse engineer most anything if necessary, but I would rather follow at this point then take off into the jungle with a machete. ;)

andresohc
08-01-2004, 10:11 PM
"but I would rather follow at this point then take off into the jungle with a machete"

(To blaze my own path is what I meant in case anyone is scratching their heads and ducking), :D

Ian Mackenzie
08-02-2004, 03:52 AM
Okay,

The 4345 is basically a larger version of the 4344, the box is 9 cuft3 with the 18 inch 2245 woofer, all other aspects are similar.

The internal dimensions are in inches 28 wide, 39 high , 16 deep.
The material is 1 ich mdf but would consider laminated MDF for birch ply for the front baffle.

Here is my earlier sketch of the front baffle.

The woofer in this model is centred in the baffle , theres no where else for it to go. I will post the other drawings soon enough which were redrawn for the 4344, so I will modify the dimensions to avoid a total re work.

The 4345 is more difficult to build because its bigger and heavier to handle, so enter at your own risk; hmm: The Waf factor ain so good either and your neighbours might move home..LOL

Ian Mackenzie
08-02-2004, 04:07 AM
Probably of more significance is just how to go about the job.

So here are some practical hints for the 4344/4345 builders.

Its not a weekend L100 project, more like 3-6 months..a labour of love. Take your time, plan out the steps for the job and how you are going to go about it. In my 4345 there were over 50 tasks to complete not counting the paint job.

This is a tricky project, the baffles are mirror image pairs and the enclosure must be assembled to a prescribed order.

In particular care must be taken with the baffle cut out. As they are mirror image pairs for left and right and you must be careful to draw up the layout of the baffle before cutting and check everthing at least twice.

I will redraw the overall baffle dimensions for the actual baffle size as per the 4344 construction approach.

You must have a Jasper circle Jig and a powerful Router with a new cutter, plenty of ventilation and a Jig to hold the baffle.

Ian

Ian Mackenzie
08-02-2004, 04:39 AM
I would cut the baffle and then router the driver cut outs as the first steps, taking care to sketch up you plans life size on the baffles, check and re check before any cutting.

Then proceed for with the driver bolt holes and fit up the the horn, and slot. These fittings are precise so care must be taken as you only get one shot at it. Make a practise Jig for the horn and slot first to ensure a perfect fit up of the /horn drivers. This also applies to the 2122H, there is little tolerance for error here. A drill press/jig will help as the holes must be perfectly plumb.

If you are using a laminated baffle do the above step after the fabrication of the laminate as the holes will fill with glue!

When you are done there cut and trim the port holes for a snug fit. You can make the outer skin the front edge and insert the port into the rear layer, it looks great done that way. Alternatively if using 1 inch MDF, place the layer of 3/4 MDF behind the baffle and use as an insert.

If you plan to use laminated 3/4 MDF like I did, then laminating is the next step. So make a frame jig to hold the baffles when they are glued to stop them moving. Use plenty of PVA glue and pressure with Glad Wrap clear plastic film around the edges to stop the baffles adhering to the jig. You will also need to rebate out the rear layer for the flang of the 2307 and 2405. I did this pre the laminating but suit yourself.

When the baffle is complete the Dog Box panels can be cut. Assemble with glue/screw and then carefully postion on the rear of the baffle allowing clearance of the Pads (and ports in the case of the 4345). The Dog Box should then be glued and screwed into place.

A support brace for the compression driver like this one will need to be arranged. I used hard rubber as a support to avoid vibrations. You can also ues a strap around the driver if you like but the weight should be sufficient to stop it going and where. (unless you plan to ship the boxes).

You will also need to consider how to go about assembling the plate for the Foil Cal. I used 3mm aluminium plate and cut it to size, the carefully drilled the holes for the pad knobs and fitted it into a rebated area within the front baffle as seen in the picture below.

That about does the baffles, but its about a weeks work in that.

Ian

Ian Mackenzie
08-02-2004, 04:43 AM
Here the baffle being fabricated/assembled.


Ian

Ian Mackenzie
08-02-2004, 04:49 AM
Here the Dog Box being assmbled and mounted on the rear of the baffle. As you can see there is zero tolerance for errors, so take care.

Ian

Ian Mackenzie
08-02-2004, 04:53 AM
I will post the other drawings later in the week.

Ian

Ian Mackenzie
08-02-2004, 05:00 AM
With any luck your baffles wiill turn out like this example.

The details and exacting features are all visible.

Ian

Ian Mackenzie
08-05-2004, 05:18 AM
Before I do any more posting here I would like to ask Don how these types of threads or edited aspects there of can be stored and indexed or catalogued on the forums or in the JBL/Lansing Library so that a member can see that its available.

(There seems little point to it if this can't be arranged.)

I would add a lot of very useful technical information and images are posted of equal or greater value than in this thread and then lost as all the new threads roll forward and i don't see the search function as a solution.

We seem to be treading over old ground a lot and as a Heritage Forum I think we could be doing this better.

Don, can you assist?

Ian

Hofmannhp
08-06-2004, 08:05 AM
Originally posted by Ian Mackenzie
Before I do any more posting here I would like to ask Don how these types of threads or edited aspects there of can be stored and indexed or catalogued on the forums or in the JBL/Lansing Library so that a member can see that its available.
......Don, can you assist?

Ian

:yes:
Ian....I agree completely ......

I think that we can add some more heritage systems in the future to this kind of data base.

Don, what do you think...?

HP

Ian Mackenzie
08-21-2004, 04:20 PM
Apparently there is reference area, so at some stage when these drawings can be put into Autocad they could be saved there perhaps.

Go here for more practical information about building the 4345.

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&threadid=952

I will be opening my own home page as a reference of these designs shortly, in the interim if you need assistance send me a Pm.

Here are the remaining drawings, adapted from the 4344 drawings posted earlier.

Ian

Ian Mackenzie
08-21-2004, 04:27 PM
More dawings.

Ian Mackenzie
08-21-2004, 04:29 PM
This is the front elevation.

Ian Mackenzie
08-21-2004, 04:33 PM
Here is the top elevation.

Ian Mackenzie
08-21-2004, 04:35 PM
This drawing details the enclosure joints.

Ian Mackenzie
08-21-2004, 04:37 PM
Here is detailed side elevation of the bracing.

Ian Mackenzie
08-21-2004, 04:42 PM
Here the rear elevation with details of the bracing and boot opening.

Ian

B&KMan
04-16-2005, 05:13 PM
The layout....I just followed the schematic

Ian

Hello again Mr Mackenzie...

I continue my quest of information for buiding a DC charge blend caps for replace my 3143 networks (4343)

Do you have a better pict and any complementary info for modificstion of schematic ???

Thanks for all

Jean :)

geowal3
04-18-2005, 06:25 PM
Hope I can interject a related question here about the 3145 "equivalent circuits" provided by Giskard for Ians 4345 project, without twisting this thread too badly.

I dont understand much at all about these circuits but am confident I can assemble them. I am working up a variant of a 4345 (triamped, 2245H, 2123H and 2441/2405, crossed over at 250 and 1100Hz). Many thanks to Ian for all his detailed posting on "how to", and all the others that contributed so freely of their time along the way, especially Giskard!

Will the equivalent circuit for the 2421 work for the 2441? I am assuming that since they are both 16 ohms nominal that they will. Secondly, in both the 2405 and 2421 equivalent circuits, there are resistors shown in series with the inductors; are these actual resistors or are they just the resistance values of the inductors?

Many thanks!

Ian Mackenzie
04-18-2005, 11:08 PM
I am away at the moment, I will try and respond by the weekend.

Ian

4313B
04-20-2005, 08:54 AM
My original equivalent circuit:

4313B
04-20-2005, 08:58 AM
New simplified proposal - someone with custom 4344's would have to give it a try. It should be perfect. :p

DCR values are extremely important and this model is based on Jantzen 18 and 20 AWG coils.

Use gangs of resistors to achieve proper power handling.

4313B
04-20-2005, 09:02 AM
Hope I can interject a related question here about the 3145 "equivalent circuits" provided by Giskard for Ians 4345 project, without twisting this thread too badly.

Will the equivalent circuit for the 2421 work for the 2441? I am assuming that since they are both 16 ohms nominal that they will. Secondly, in both the 2405 and 2421 equivalent circuits, there are resistors shown in series with the inductors; are these actual resistors or are they just the resistance values of the inductors?
I edited the schematics to show the DCR.

You can try it with the 2441 and let us know what happens.

Ian Mackenzie
04-20-2005, 02:20 PM
I am curious, what are the differences in the voltages drives b/n the equivalent circuit with the simplified schematic?

Ian

4313B
04-20-2005, 03:24 PM
Orange is "old equivalent", green is "new equivalent", white is actual "tapped autotransformer" model.

Orange was done from 1981 Engineering Design Specification voltage drive using datapoints - all L-Pads open - all 8 ohm dummy loads.

There is enough slop in the L-Pads that both are viable - the new model should be cheaper to build with less parts.

geowal3
04-20-2005, 06:57 PM
Many thanks Giskard! I certainly will provide feedback on "what happens" using a 2441 at the end of this project - but it will be a while.

I see another possible pitfall, but don't know enough to evaluate the problem. The graph below shows output of the electronic crossover I am working with. ("Stuck with" would be more apt - it's fixed at 1100 Hz 24db/Oct and built into a BGW triamp, and there no changing it now).

Is there a problem in with the way that the high pass "new equivalent circuit" for the 2441/2421 will "see" the input from the electonic crossover, and/or a problem between the MF output to the 2123 and the new equivalent circuit?

Robh3606
04-20-2005, 07:17 PM
"Is there a problem in with the way that the high pass "new equivalent circuit" for the 2441/2421 will "see" the input from the electonic crossover, and/or a problem between the MF output to the 2123 and the new equivalent circuit?"

You have me confused:blink: The electronic crossover will be driving the amp. The speaker crossover will see a bandwidth limited input from the amp and filter it the same way as a fullrange signal. Is that rise in HF response real on the graph??? If it is it will change the response independent of the crossover. You may be able to use the 2405 trim pot to get most of it. It will change the slope a bit on the 2421/2441 roll off to the 2405. Can you tailor it for flat response by changing out part values in the crossover?? OK You have a 3 way active crossover at 300Hz and 1100Hz. The HF driver is a 2421 or 2441 and the UHF is a 2405?? Why are you concerned with the High crossover point?? You only have to build the low pass half of the 2421/2441 filter and the 2405 High pass. Once you match the attenuation between the 2421/2405 the active will set the average level for both drivers and you will have the pots to adjust. The 2123 is bracketed by the filters in the active crossover and should not be affected at all. I also run an active 4 way with points at 50Hz 300Hz 1200Hz same slopes 24dB L/R. Use the same midrange driver 2123. It should work fine using the passive between the 2421/2441 and the 2405.

Rob:)

geowal3
04-20-2005, 09:57 PM
Rob, appreciate the carefully crafted response. Sorry I have you confused - I thought I was the one confused. Your bottom line is very reassuring! Here's what I think I know:

1. Yes, the rise in HF response is real. As I understand it, it is designed in to the beast as purpose built for a JBL 2441 and a CD horn - but don't hold me accountable on that! However, I don't believe that is a problem for me. First, I am 61. Second, in my former life I spent 27 years in the army, about half of it around tanks. So my ears are probably "down" something like 150dB @2500Hz or whatever. (It's not that bad, I know I can here above 7K for sure!!:))

2. IF there is a problem in the HF or UHF range, as you say, the pads in the passive crossover may handle it, but I cannot make any changes in the electronic crossover (WAY over my head!). I would not tackle it myself, and having BGW (or, actually the company that bought them out in 2003) do it would probably be comparable to the cost of, say, a space shuttle launch.

3. In my very limited understanding, it seems there may be a "gap" between the 2123 and the 2441, (how do I say this?), because the 2123 (MF) is "down more" on the triamp graph relative to the output to the 2441 on Giskard's graph. Even more amateurishly put I suppose, in Giskard's graph, the 2441 lower end is related to a particular slope for the MF (in my case a 2123 but I don't think that is relevant). On the triamp graph, the MF output appears to match the HF output at a lower point (maybe 1020Hz?) than on Giskard's graph (maybe 1080Hz?). Am I reading the graphs correctly, and if I am, is this a problem? Or will adjusting the output levels of the triamp handle this "discrepancy"?

Thanks for your patience!

Robh3606
04-21-2005, 04:44 PM
Hello geowal


Giskards graphs also show the network attenuation that is needed to match the drivers outputs. Both the 2421 and 2405 need a good bit of attenuation because of their higher sensitivities. With the active crossover as long as you can adjust the individual drivers you should be fine.

Rob:)

geowal3
04-24-2005, 08:13 AM
Thanks for the insights Rob. I have been trying to get down to the brass tacks of ordering components for these networks. Two concerns arise.

First, Giskard says to use "gangs of resistors" for proper power handling. How do I determine the handling capacity to shoot for ? The 2441 is rated at 150 Watts @ 1KHz, but I would never come close to cranking it that high, so what's a reasonable level? I realize this is a flaky question, but can someone provide a rough guideline?

Then, once that answer is in hand, how do you determine the number and value of resistors to satisfy a given requirement? Let's say the desired power handling capacity is 60 watts, and, as an example, let's take the 15 ohm resistor in Giskard's HF network in post 170. Using 10 watt resistors, I would need six 90 ohm resistors in parallel, correct?

Secondly, I have been researching numerous threads on the forum to learn more about what capacitors to get. What a blackhole topic that is !!! Along the way I have read quite a bit about charge coupled networks being very worth the extra expense. Presuming that would be true in this case, how would these circuits be modified?

4313B
04-26-2005, 08:58 PM
First, Giskard says to use "gangs of resistors" for proper power handling. How do I determine the handling capacity to shoot for ?Well you could use a calculator program as found here (http://www.bcae1.com/lpad.htm).

woodstocksound
04-28-2005, 05:35 AM
Under Construction

This thread will be dedicated to those members wishing to construct the vintage JBL 4345/4344 Professional Series Studio Monitors.

Over the next few weeks I will document blue prints (in JBL Blue..LOL) and provide a Step by Step Guide to Enclosure and Crossover Network Design & Construction.

Some of you will have already been this route with the 4343 so please your collective wisdom and knowledge is most welcome

Ian Mackenzie.

http://audioheritage.org/vbulletin/images/smilies/cool.gifRob ,do you know of anyone who would have the drawings for the JBL 4550 BKA cabinet ? Any help would be much appreciated. Thanks... Darryl /Woodstock Sound

Robh3606
04-28-2005, 09:13 AM
Hello George

"Then, once that answer is in hand, how do you determine the number and value of resistors to satisfy a given requirement? Let's say the desired power handling capacity is 60 watts, and, as an example, let's take the 15 ohm resistor in Giskard's HF network in post 170. Using 10 watt resistors, I would need six 90 ohm resistors in parallel, correct?"

Yes

"Secondly, I have been researching numerous threads on the forum to learn more about what capacitors to get. What a blackhole topic that is !!! Along the way I have read quite a bit about charge coupled networks being very worth the extra expense. Presuming that would be true in this case, how would these circuits be modified?"

Take a look at the 4343 Crossover Mod Thread. It's simple just double the capacitance and put 2 in series with a 3 Meg Resistor at the junction of the 2 caps.

Hello Darryl

"Rob ,do you know of anyone who would have the drawings for the JBL 4550 BKA cabinet ? Any help would be much appreciated. Thanks... Darryl /Woodstock Sound"

No and I don't see them in the Library. Start a new thread in the Tech Help forum. I think there are people who do have them and this question is going to get lost. Someone will step up if they have them.

Rob:)

Ian Mackenzie
12-09-2005, 03:35 PM
Orange is "old equivalent", green is "new equivalent", white is actual "tapped autotransformer" model.

Orange was done from 1981 Engineering Design Specification voltage drive using datapoints - all L-Pads open - all 8 ohm dummy loads.

There is enough slop in the L-Pads that both are viable - the new model should be cheaper to build with less parts.

Here is a request for another iteration.

Lets assume for a moment most will want to bi amp these and the 4344.

I note the 3145 midrange passband filter has 2.5 R fixed L pad and a variable pad.

The penny drops that the essence of bi amping to gain maximum power and damping on the cone drivers. So why do we need to Pad back the midrange filter at all and in doing so sacrific sensitivity and power amp head room?

(The midrange can still be balanced via the Hf amp level although not independently of the Hf & Uhf. Although I tend to think its much easier to set the levels of the horn and slot against the midrange anyway and then adjust the woofer level)

I would therefore like to propose running the 2122H without a fixed and variable pad and revising with fix pads for the Hf & UHf filters in the "new equivalent filter" by Giskard.

It would be much appreciated for Giskard to review the above and publish a revision when time permits.


Ian

4313B
12-09-2005, 04:10 PM
That would be worthwhile.

Robh3606
12-09-2005, 05:46 PM
Well just make sure that those resistors don't effect the Q of the bandpass filters. I have run the 2122 strarght up and you get a rather pronounced bump without the filter in place.

Rob:)

Ian Mackenzie
12-09-2005, 06:37 PM
Well just make sure that those resistors don't effect the Q of the bandpass filters. I have run the 2122 strarght up and you get a rather pronounced bump without the filter in place.

Rob:)

Rob,

I assume you meant the resisters.

Ian

Robh3606
12-09-2005, 06:41 PM
"Rob,

I assume you meant the resisters.

Ian"

Yes just see what happens without them may not do a thing but???

Rob:)

4313B
12-15-2005, 02:36 PM
I would therefore like to propose running the 2122H without a fixed and variable pad and revising with fix pads for the Hf & UHf filters in the "new equivalent filter" by Giskard.

It would be much appreciated for Giskard to review the above and publish a revision when time permits.You can go ahead and pull the 3 dB pad from the 2122H when bi-amping. That will be like doubling the power of your driving amp. The original network was based on the low pass inductor (1.8 mH) having a DCR around 0.6 ohms so try to maintain that. e.g. Using an inductor with 0.2 ohms DCR shifts the crossover down by roughly 50 Hz. A Zobel based on 10 ohms might also be beneficial for tweeking since you would be removing the L-Pad.

Well just make sure that those resistors don't effect the Q of the bandpass filters.Absolutely. In this particular instance it is evident by inspection that were are looking at a 3 dB pad based on an 8 ohm model. The DCR of the inductor will affect the slope and should be kept around 0.6 ohms. The Solen 16 AWG or 18 AWG would be decent.

Ian Mackenzie
12-15-2005, 09:32 PM
Okay,

But what I meant was the fixed pad drops the level 3 db, the L pad is normally also set at - 3db from max for zero position.

This suggests the 2122 is pad back more than -3 net.

If I dropped the fixed pad and turn up the L pad full I wonder if there would be enough level in the HF and uhf filters, even with them up full?

Ah, I think I get it There was a certain amount of real gain in the 2122H bandpass filter and some real loss of gain in the 2245H low pass filter due to choke 5.4 Mh dcr. That net difference could account for the fixed pad attenuation and the -3 db flat position for the mid range L pad. And of course it was voiced and then balanced to sound right..the numbers don't always tell the whole story!

They must have had a hell of a time sorting out those voltage drives.....
G.T did a commendable job calibrating the 4345 L pads.

I will try bypassing the 2122H fixed pad this weekend.

Ian

Ian Mackenzie
12-25-2005, 02:21 PM
You can go ahead and pull the 3 dB pad from the 2122H when bi-amping. That will be like doubling the power of your driving amp. The original network was based on the low pass inductor (1.8 mH) having a DCR around 0.6 ohms so try to maintain that. e.g. Using an inductor with 0.2 ohms DCR shifts the crossover down by roughly 50 Hz. A Zobel based on 10 ohms might also be beneficial for tweeking since you would be removing the L-Pad.
Absolutely. In this particular instance it is evident by inspection that were are looking at a 3 dB pad based on an 8 ohm model. The DCR of the inductor will affect the slope and should be kept around 0.6 ohms. The Solen 16 AWG or 18 AWG would be decent.

I am also busy winding coils for the new equivalent design for trial over the Christmas break.

What assumptions/values did you make/use in calculating the fixed pad. trying to work out your values for the horn fixed pad and 2405 ?


Am I correct in assuming you were shooting for a 10-11 ohm impediance on the horn for the fix pad values of 5.6R and 8.6 (15/20)?

Given the 2307/2308 sensitivity of 108 my guess a 10-11 ohm impediance load seen by the crossover, is about -7 db for the fixed pad, about -2 db from the 20R shunted on the horn and about -4 slack on the variable L Pad = 95 db for 0 position.

The 2405 would also appear to be perhaps about 10 ohms impediance hence the 6.8R / 6.8R values which gives about -8 db (105db -8 for the fixed pad -3 db in the variable L pad =95 db for 0 db position.

Ian

Ian Mackenzie
12-25-2005, 03:25 PM
Thanks Giskard,

If I recover sufficiently today I will have a crack to firing it up tonight!

(had to polished off most of a bottle of sparkling Shiraz yesterday ..goes well with Turkey...nice)

Ian

Tom Loizeaux
12-25-2005, 09:10 PM
I like the way this discussion is going. Designing a crossover for a 4344 (45) would be a very useful exercise!
I agree that if one were building a new pair of these speakers, they'd probably want to run them in bi-amp mode. Given that, the passive crossover would only need to deal with the 10", HF compression driver and 2405 slot. Since the 10" (2122 or 2123) would be the least efficient of these three componants, it should run without any pad (except to deliver the correct slope with the compression driver). Then it may be best to pad the compression driver and slot with stepped attenuators. You wouldn't need more then 6 dB of level adjustment. This would keep variable L Pads out of the crossover and should lead to superior performance.

Tom

Ian Mackenzie
12-25-2005, 11:27 PM
Glad someone caught on!

Tom Loizeaux
12-26-2005, 05:43 PM
I think there would be great interest, at least here in the Forum, for buying a complete set of detailed plans for building the 4344.
Since a few of us have built, or are building these, it would be smart to have you guys pool your plans, have someone refine, adjust and proof these, and ultimately make them available to prospective 4344 builders. The proceeds of the sale of these could go to support the Forum.
Along with the plans could also be the schematic for the crossover for these "upgraded" bi-amped 4344s. The details of this crossover are currently being worked on (thanks Ian and Giskard).
I, for one, would love to have accurate plans, maybe even including some life-size templates, etc, so when I'm ready to undertake that project, I'd have all the detailed info I'd need.
Though I love my 4343s, I would consider building the 4344s, using the "upgraded" drivers and crossover. I'm sure they would be an improvement, even if only slight, over my vintage 4343s. Having these plans and knowing I could get the correct drivers and crossover parts would make this a very attractive project down the road.

So who's going to step up and agree to coordinate getting these plans and crossover info together?

Tom

4313B
12-26-2005, 07:30 PM
I've already done too much for this forum in the past five years. I don't need to step up to anything...

I've gone over this 4344 stuff a few times. Ian has real life hands-on experience and knows what to do.

Ian Mackenzie
12-26-2005, 08:47 PM
Look, my simple response is use the search button and keep searching and asking the right questions for about 6 months. Then you will have an inkling of what the product is about......

Building one of these is not something that comes straight off the blue print and I think any notion of "selling" plans is totally off the wall. What would be worth while and is sadly lacking is a product profile like the 4430 in the Library.There's more factual knowledge there than half the crap slapped over the forums by people who are simply clueless and guessing.

The same perspective applies to the 4343-4344-4345. Its very complicated, a large investment, an absolutely huge job and you need a shit load of resources and its a steep learning curve all the way to the end. ie Its not just case of having a router, but how to use one skilfully in new and challenging situations, devising and making up special jigs etc.

A mentor is a must!

I generally find a good deal self satisfaction from first collecting the facts about something I know little or nothing about rather than filing a request for everthing on a silver platter.

That way you take less for granted and have a lot more respect for those who put in the first hard yards.

Hofmannhp
12-27-2005, 12:48 AM
I think there would be great interest, at least here in the Forum, for buying a complete set of detailed plans for building the 4344.
...........
So who's going to step up and agree to coordinate getting these plans and crossover info together?
Tom

Hi Tom,

I can do it , but need a precise measurement of original cabs.....(handdrawn)
incl. the type of used material.

HP

saeman
12-27-2005, 12:52 PM
Building one of these is not something that comes straight off the blue print and I think any notion of "selling" plans is totally off the wall. What would be worth while and is sadly lacking is a product profile like the 4430 in the Library.There's more factual knowledge there than half the crap slapped over the forums by people who are simply clueless and guessing.

A mentor is a must!



Hello Ian - If you or another forum member decides to build a "Product Profile" on the 4343 - 4344 - 4345, I would be happy to provide the plans that I have accumulated for these monitor enclosures. I have detailed drawings for the 4343 and the 4345. My 4344 plans are lacking a few details but are close. Although the original baffle layout on the 4344 has flaws, I have original baffle info should anyone want it.

My plans are no more than detailed drawings of how JBL built the cabinets and of course, as you well know by now, I do not have the electronic background to assist beyond cabinet construction. I would gladly provide what I have with the understanding that they are just detailed drawings. There is no amount of information that could be added to these drawings, that would allow an individual with no skills to produce a quality end product. The individual builder must have the knowledge to choose correct materials and make necessary joints to build the enclosure.

I did some time ago provide detailed drawings of the 4350. To my knowledge nobody to this date has bellied up to the bar and started building a pair. The information is none the less there.

I don't think money should change hands for this type of information. Unless I've missed something in my time on the forum, the members have freely shared info in their respective areas of expertise. I have benefitted many times from you, Giskard and many others on my projects. I'm happy to return the favor and provide any info that I have.

Some good thoughts and some rambling - Rick