I've edited selected posts and placed them on the Speaker forums of Diy audio.The 4343 has been discussed over there in a number of threads and some modifications
It will be interesting to gauge the reaction and perhaps it will sattract more participation and some new members to Lansing Heritage forums.
I might even raffle off an active crossover kit to a lucky participant...you have to be in it to win it!
The New Doctor
Upgrade 3 – Upgrade 4343 drivers to 4343B spec.
Replace 2231A with 2231H
Replace 2121 with 2121H
Below are the various iterations of this model in the JBL Studio Series.
And some background information on the ins and outs of the 2231A-2231H and the 2235H.
The best post is here from Don:http://www.audioheritage.org/vbullet...7&postcount=24
The bottom line is if you have a 2231A, try and find a 2235H. If you have a 2231H, check the recone is A 2235h recone.
As to the 2121A, if you can find a 2121H go for it but they are as scarce as hens teeth.
Other threads with interesting information.
http://www.audioheritage.org/vbullet...ighlight=2231H
http://www.audioheritage.org/vbullet...ighlight=2231H
http://www.audioheritage.org/vbullet...ighlight=2231H
http://www.audioheritage.org/vbullet...ighlight=2231H
http://www.audioheritage.org/vbullet...ighlight=2231H
Upgrade 4 – Bypass the bi-amp switch.
See post 101 106 by Jean:
http://www.audioheritage.org/vbullet...&postcount=101
http://www.audioheritage.org/vbullet...&postcount=106
Please be aware the colour coding of the wiring in the 4343 is a brain teaser.
Firstly, decide if you intend to biamp or run passive, obviously bypassing this switch will made either mode permanent!
Yoy may also wish to upgrade to superior binding post while performance this update. We will revisit this later I hope with actual images of a step by step guide to bypassing the switch
Upgrade 5 – Upgrade the stock crossovers.
A/ Bypassing capacitors (re route Hf and Uhf signals direct to input terminal)
B/ Replace capacitors. "''' ""
C/ Charge coupling
D/ Upgrade crossover to 3145 spec.
Okay, this is the Juicy post you have all been waiting for...Muhhaha.
A/ Bypassing capacitors (re route Hf anf Uhf signals direct to input terminal)
As we outlined earlier, some of you might just want to dabble and to a large extent preserve the vintage of the 3143 and just make subtle upgrades.
If this is the case I recommend bypassing all the capacitors with Audio Cap PPT Theta 0.01 uf film foil capacitors (Part Number 027-700 available from Parts Express).
Bypassing was essentially the first major impovement JBL did in the evolution of their crossover developement.
While you are at it definately re route the HF and UHF signal directly to the Red input terminal or the input side of the 52 uf capacitor. (see schematic below)
Someone might be kind enough to post a redrawn schematic.
B/ Replace capacitors.
This is a more advanced update and it is open to more user preference for parts. Do not attempt this update A) Without careful planning B) Unless you are confident you have the skills.
It is assumed that the existing stock capacitors will be changed out. It is important that what every you replace them with fits in the existing space.
This may not be the case with some Film foil types.
As to recommendations, I can recommend both the Hovland and Auricaps from personal experience. No doubt there are other good capacitors and some may also prefer to replace and bypass. My suggesting is just go for a really good capacitor if you are attemping to change out the stock parts..you only want to be doing this once.
C/Charge Coupling
This is the next level of upgrade and perhaps the most popular crossover upgrade for the crossover fanatics.
JBL has been charge coupling some of its designs for some time now.The benefits can be found in the Library and on numerous threads on the forums. This upgrade will require building a complete new crossover and again will require advanced skills. If you would like to do this and are not confident to doing it your self there are members on the forums who may be able to offer assistance for a fee.
I would pitch this upgrade with the option of going to the upgrade to stock 4344 crossover (3145) as there are design benefits to be had in this iteration and they go hand in hand with the driver upgrade to the 4344.
I do not have schematic of a charge coupled 3143 so if there is interest here someone might be kind enough to post a schematic.
D/ Upgrade crossover to 3145 spec.
As mentioned above this upgrade assumes you intend to upgrade your drivers to the 4344 spec (the 2231A - 2235H , 2121A to 2122H and 2420 to 2425J)
Essentially the same rules apply as in upgrade C.
This crossover is even more advanced and has different characteristics to match the 4344 drivers.
The 3145 network however uses parts no longer avaialble. Fortunately there is an equivalent network to the original stock 4344 (3145 crossover) designed by Giskard (JBL Lansing Heritage Forums Guru). There is also a further refinement of this original stock crossover in the forum of a new equivalent 3145 network that has been developed recently by Giskard.
They can be built using film foil capacitors, bypassed film foil or charge coupled.
It may also be an option to locate these networks external to the enclosure due to their size and for purely acoustic reasons.
I will post a schematic later.
So you have lots of options and each will appeal to one member or another for different reasons.....
More to follow;
The New Doctor
Those desiring to retain the switching capability, but wanting to upgrade to a new and better enclosed switch might consider this:
http://www.electro-nc.com/rotaryus/c4.pdf
$20 from Newark Electronics, but you may have to work out your own shaft extension or custom knob....
If you have to have switching (I am not sure why that might be) that is always a possibility. Thanks Zlilchster.
But essentially its another junction the signal has to cross...electrons hate jumping from one condutor to another.
Ages ago Speaker Builder did a revamp of the 4333, the switch was sighted as degrading audio performance.
Upgrade 6 – Discussion on Bi-amping.
Pros and cons.
Active crossovers available on the market;
Okay we have prevous gone over this but for the record biamping improves bass clarityand provides improvements in dynamic range (but there is a downside)
http://www.audioheritage.org/vbullet...3&postcount=61
Refer to the crossover updates to re route the HF and UHF driver signals and you will notice further improvements.
If however you are currently running full passive mode and have only one amp I encourage you to do the crossover and other upgrades and note the improvements before proceeding to bi amping.
Unfortunately, the fidelity of all but the most premium of active crossovers degrades what may be termed the HiFi aspects of the sound quaility. This will be more noticable if you have premium grade amplification (such as a Valve amp like a Cary, Audio Research a Passlabs or other cut above average amps).
If you are considering your options, your strategy might be to spend funds on a good crossover upgrade (plus the other updates) and enjoy the benefits of improved timbre and clarity and transparency as being more important than the last ounce of bass definition.
You may even then go for a better amp.
One interesting comment that has surfaced on the diyaudio forums:
Interesting project, Ian.
I must admit, the "shoutyness" that you have had success in removing, seems to very much be part of the JBL house sound, even affecting their PA boxes and install systems like the Control range. In the Brit audio industry, it is always known as the "American" sound.
Yet, it doesn't seem to be a characteristic of the JBL drivers that I have listened to individually, so your experiences of crossover reworking removing this is facinating. The question has to be "Why that voicing"?
__________________
Al
Our subjective comparisons in the development of the project suggest this is very much the case.
On the other hand if you want a loud, snappy and dynamic sound and can live with some loss of transparency and brassy tonality then go for biamping. For what ever reason this is a namesake of the 4343 historically but we're about to change all that.
It is surprising how well the JBL 4343 upgraded to the 4344 spec can etch out the impact of ampifiers and associated electronics on the original signal.
In summary its a lot more difficult to get the best of both worlds with biamping but if you really have to have it then keep following this thread.
The New Doctor
I've thought about what detail I might be losing because of this rotary switch and have considrered bypassing it since I only run my 4343s in the bi-amp mode. I don't, however, want to clip the wires. Being able to return this to stock is important to me.
If it's possible to "jump" the switch by soldering in short copper wires between certain terminals and make it run in the bi-amp mode, I'd be intertested.
Can anyone make a drawing of this switch showing how to jump it for semi-permanate bi-amp mode?
Thanks,
Tom
Good point Tom,
Lets explore this a bit futher and see what we come up with.
Time for a tea break.
Over and out.
I, too, am interested in your "powered crossover" for the 4343.
Please keep us posted.
Tom
Okay I will note your interest.
Should there be enough interest in this particular device I will set forth and do a one off production run.
While not wishing to elaborate to much at this point it will be minimalist black box so to speak for the 4343-4344 owner "only" but full of very nice goodies and with a few tricks I've got up my sleeve....
The New Doctor
Upgrade 6 – Upgrade drivers to 4344 spec.
1. Replace or recone LF drivers to 2235H
2. Replace or recone MF drivers to 2122H
3. Replace or rediaphragm HF compression driver to 2425J.
1 Well I have discussed that to death above.
2. The 2122H is an upgrade of the 2121 and according to Giskard and others a better driver.
Here are a number of links that will answer all your questions and more!
http://www.audioheritage.org/vbullet...6&postcount=11
http://www.audioheritage.org/vbullet...82&postcount=7
http://www.audioheritage.org/vbullet...95&postcount=4
http://www.audioheritage.org/vbullet...ighlight=2122H
http://www.audioheritage.org/vbullet...ighlight=2122H
http://www.audioheritage.org/vbullet...46&postcount=2
http://www.audioheritage.org/vbullet...91&postcount=3
http://www.audioheritage.org/vbullet...ighlight=2122H
http://www.audioheritage.org/vbullet...ighlight=2122H
http://www.audioheritage.org/vbullet...ighlight=2122H
http://www.audioheritage.org/vbullet...ighlight=2122H
http://www.audioheritage.org/vbullet...ighlight=2122H
3. This is an interested upgrade.
Firstly, if you own a stock 4343 I would think twice about pitching out the 2420 for the 2425J. Some members have reported better sonics from the Alnico 2420/2421.
Secondly, I am not sure if the upgrade to 2121 aluminium diaphragm is still available as a spare part from JBL, I know they are around on E bay sometimes......someone might want to check this out.
Regardless either is better than the original 2420 diaphragm.
The aluminuim version of the diamond surround diaphragm apparently sounds better. If you are really keen you might want to sniff out the aquaplas coated 275nd diaphragms. There might be some technical variations but I think the results would be rather tasty.
The issue with these things is mass, stiffness and self damping....much like any other driver actually.
There are a number of threads that explain how these diaphragms work and so on and so forth.
Please arrange the upgrading of the diaphragm by a JBL authorised service centre. Edgewound is one Authorised JBL service agent I am aware of on the forums although I have not heard much of him lately.
My recommendation is don't do any driver upgrades yourself, just call your local JBL service agent and tell them what you need.
Upgrade 7 – Converting to Hi End Crossovers.
1. Internal vs External placement
2. Passive
3. Active
1. Internal vs External placement
The theory and to some extent subjectively some listeners say that external crossovers sound better. I have never seen any scientifically conclusive analysis that confirms this one way or the other however I know from personal experience external crossovers do sound in some instances different. There is an apparent deeper silence between the notes and the speaker tends to sound more clean and precise.
It also depends on how far you want to go. Some say if you can carefully hot melt glue the crossover parts down on a backing board they will not vibrate much. This is where a bit of black art comes into play.
I would also point out that due to layout considerations however, internal crossovers tend to be cramped up in a small space and therefore compromised. Putting everything in na confined space is not always ideal electrically for the filter to perform at their best due to mutual coupling of coils and isolation of filters from one another due to poor wiring layout.
The design of a external crossover is more likely to perform to the ideal due to less practical/physical limitiations of layout.
In the case of the charge coupled networks I would suggest this is welcome due to the complexity invloved.
If you do plan on an external network you will need to arrange a suitable means of cabling to the outside world. I used an 8 Pole Speakon Plug and Socket. There a several advantages with this style of connector, its air-tight, has very good electrical characertistics, takes a 13 gauge cable and the polarity of the individual driver cabling is identified and maintained without fear of error.
Phasing errors are by far the single biggest issue with reworking a multiway network.
You can place the external crossover on the rear of the speaker or in its own dedicated enclosure if you wish.
HI End Passive Parts.
Well, the skys the limit here and I have had many members ask for recommendations. There are dozens of brands, Auricaps, Mundorf, Hovlands, Cardas, Audiocap and North Creek to name a few.
The use of Solen fast caps bypassed with hi quality film foils and charge coupled is also another avenue as used by JBL.
In this respect its a trade off of complexity versus cost.
Ideally the cost of crossover should account for 1/3 the total cost of the system according to one speaker builder author. So if the bill of parts appears expensive don't finch..its the way it is. Just don't tell your wife.
Mills resisters are preferred for in signal path locations. Coils should be chosen based on the specific electrical characteristics. Do not use iron laminated cores unless specified.
Wire, well I am not even going to go there, use common sense. Wire gauge should be proportional to current.
Active
We have discussed this above. If you propose to layout a fair amount of cash on passive crossover parts don't expect a miracle with bi amping unless your unit is up to spec. Otherwise go full passive. The JBL 5235 and the Ashly active crossovers for what they are aren't bad but are not deserving of any crossover upgrades discussed in this project.
Using high quality capacitors and all the other updates we have discussed will absolutely improve the transparency of the loudspeaker. But it will also let through the warts and all.
All the stuff upstream has to come down stream, if its dirty it will stand out like dogs balls. You will hear the impurities in the form of sonic glare or a cloudy haze, the bass lacking definition and the loss of fine details and ambiance.
This is why I have been referring back to a total system approach. Just pretend you are a UK or Japanese Hifi nut but on an industrial scale.
Ocassionally I have seen some nice units on audiophile review sites but they are few and far between. The DEQX is promising but for $3K its not cheap and a lot of wasted horse power if you are not a speaker designer wizzard.
I will give the idea of organising a package based on the my class A discrete crossover some thought if there is sufficent interest. As mentioned above it will be be a minimalist purpose built limited edition Hi End crossover for the 4343-4344.
Everything has to be in balance.
http://www.audioheritage.org/vbullet...8&postcount=50
Upgrade 8 – Cabinet Upgrades
1. Improve internal bracing.
2. Modifying the top 4343 baffle
3. Modifying the bottom 4343 baffle
4. Cabinet and grille repairs
Please refer to the images below.
It is best to limit this discussion at this point until members come forward and provide input on what they would like to do. Obviously there will be limits with what you can do with an exisiting cabinet. Some may even go the the extent of re building the enclsoures...bravo to that cause!
http://www.audioheritage.org/vbullet...0&postcount=41
http://www.audioheritage.org/vbullet...2&postcount=42
http://www.audioheritage.org/vbullet...0&postcount=41
http://www.audioheritage.org/vbullet...2&postcount=42
http://www.audioheritage.org/vbullet...2&postcount=44
This series of post has been mainly descriptive of the specific updates to flesh out the what, why and how.
The intention is to use work in progress on members own systems as the discuss focus from here on which will when completed be posted in edited form into the 4343-4344 design thread.
That way everyone who wants to particpate with a specific upgrade has the opportunity to show and talk about what they are doing and share ideas and experiences with each other.
It should all be a lot of fun, that after all is why we are here.
The stats ...134 posts and 2956 views......I told you I would not babble on to much....LOL
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