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Thread: Thoughts on these 4343 drivers

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    Thoughts on these 4343 drivers

    Friend of my is going to see a pair of 4343 in NoCal. Cabs are in decent shape. He was told the drivers were original but were reformed but no indication of where. Any thoughts on the reformed drivers? I assume the 2121 kits are no longer available? Thanks.




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    Member VinylGroove's Avatar
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    They look good very clean and well done, though the dust cap is incorrect on the 2121, which should be inverted. As long as they have enough adhesive that the cone is secure to the surround, I wouldn't change them further or worry about it.

    Just as an FYI and a plug for a great guy to deal with - I've done my own refoaming on all previeous JBL speakers that needed it, but for my 4343's I sent the 2121's and 2231a's to Matt at Utah Reconing for his refoam work. Mostly because I didn't want to mess up the rare 2121. He has connections to get anything you need for servicing speakers including full recones, whether it's currently made or not. I know other members of this forum have used him as well.

    https://www.facebook.com/utahreconing/
    (801) 419-3099

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    Thanks, he was mainly concerned about the 2121. I assume the inverted dust cap is no longer available. May have to ask matt or others. In addition to the normal glue, there's seems to be some translucent glue as well.
    EJ

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    The foam surrounds degrade over time in part due to exposure to UV light and to air pollution but unless stressed the voice coil, spider and cone should be fine and not need a full recone. The surround job looks to be well executed. If you want to check unknown LF drivers do what JBL trained reconers to do, get a phone app with a sine wave generator ( Studio Six Digital makes a good one but there are free ones ) and sweep a tone from 100 hz down to 20 hz. At a comfortable listening level about three feet from the speakers you should hear a clear tone without over tones. If you do hear overtones sweep back and forth around the frequency where the distortion is most prominent and see if you can localize the distortion. This is normally done with the speaker out of the enclosure but it's a good test for many potential issues with speakers. If testing drivers other than woofers choose an appropriate tone range, above 800hz for compression drivers, 100 - 1000 hz for mid drivers etc.

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    He will go have a listen. What are prices these days for a 4343?
    EJ

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    Quote Originally Posted by club900fe View Post
    He will go have a listen. What are prices these days for a 4343?
    EDIT: I thought Skyfi Audio sold theirs but they still have 2 listed on their site, they just took their Ebay listings down.
    It appears they had 3 pairs, sold 1 and still have 2. They've also lowered the price on the more expensive pair, which used to be $20k (Kenrick Sound territory) The Skyfi restored pair are currently $14,999 and the original pair are $16,990 asking.
    https://skyfiaudio.com/search?q=jbl+4343&type=product

    I got mine in 2021 for just under $4k on Ebay, from Northridge, CA. I had to convince the seller I would not hold them responsible if any issues arose once they left their hands and were picked up by a 3rd party transporter.

    If you live on the West Coast, you can find better deals than those of us who live inland as no one wants to ship something so huge, even if you tell them you'll handle the logistics. I looked for several years to find a good pair that was under $5k from someone who was willing to ship and they're the only ones I've ever personally found at that price that were complete.

    To anyone considering buying and moving speakers from out of state - look for people who move pinball machines or pianos on Uship.com and have feedback history. To them, a big pair of speakers is a walk in the park.

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    I'm sure people can list what they want but the real numbers are what people pay. The fact that SkyFi's two 4343 are still for sale (even after their big sale) says a lot about price.
    EJ

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    Senior Member HCSGuy's Avatar
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    Quote Originally Posted by club900fe View Post
    I'm sure people can list what they want but the real numbers are what people pay. The fact that SkyFi's two 4343 are still for sale (even after their big sale) says a lot about price.
    There’s always the balance of price versus how long they take to sell - I think a mint pair, in the US, picked up cash in hand, would probably sell for $6k or so, based on the two pairs I have sold in the last 18mos. Sellers can dream of $10k and up, but those pairs almost never sell - at least not in the U.S.
    That the internet contains a blog documenting your life does not constitute proof that your existence is valid. Sorry.

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    Member VinylGroove's Avatar
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    Quote Originally Posted by club900fe View Post
    I'm sure people can list what they want but the real numbers are what people pay. The fact that SkyFi's two 4343 are still for sale (even after their big sale) says a lot about price.
    Oops you're right. I updated my post above.

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    I imagine prices in Japan would be very high given the demand there.
    EJ

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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by club900fe View Post
    The fact that SkyFi's two 4343 are still for sale (even after their big sale) says a lot about price.
    Ouch, those prices!

    Now I don't profess to know all that much about many of the brands they feature but when they delve into my life-long specialty in their Sports Car section, I know they're attempting to shoot the moon!
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Thumbs down

    Quote Originally Posted by club900fe View Post
    I imagine prices in Japan would be very high given the demand there.
    It depends if they are refurbished by Kenji?

    There is a pair locally for sale here for $7,000 imported from Japan in 2020. They are stock in the grey enclosures.

    With these systems the diaphragms in the 2420 was the weak point. This was prior to the diamond surround in titanium which were more robust. They were prone to failure with fatigue. The phase plugs and gaps get dust and debris in them over time. This can effect the performance of the system overall.

    The question is what condition are the diaphragms in and are they the original diaphragms, aftermarket or replacement JBL diaphragms? You won’t know until you buy them and open them up. A check and clean of the compression driver is best done by a factory trained technician. Ken Haerr at Upland Loudspeaker Repairs does this work.

    Unfortunately any other substituted diaphragm will require a revision of the stock network as they were voiced to the specific characteristics of the 2420 compression driver diaphragm. Back in the day JBL used a panel of golden ears to carefully voice these systems. The crossover networks were empirically adjusted until the golden ear panel was satisfied. Such adjustment goes beyond plotting the frequency response on paper.

    After new substitute diaphragms are fitted careful measurement of the system and the network with all the drivers connected is required. Only then can re calculation of a revised network and measurement of the overall system to done correctly.

    This is the thing. Why would you spend $7,000 and listen to it if it wasn’t right! These loudspeakers are not some pieces of nostalgic trophy junk. They need careful maintenance and confirmation they are working they way they should be as they pass from one owner to another.

    FYI impedance of these 4343 dips to below 4 ohms at 1 khertz. Not ideal for all amplifiers. See curve attached.

    Best to check these things out thoroughly once you buy them. That’s when the real journey begins.
    Attached Images Attached Images  

  13. #13
    Administrator Robh3606's Avatar
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    Quote Originally Posted by Ian Mackenzie View Post

    Unfortunately any other substituted diaphragm will require a revision of the stock network as they were voiced to the specific characteristics of the 2420 compression driver diaphragm. Back in the day JBL used a panel of golden ears to carefully voice these systems. The crossover networks were empirically adjusted until the golden ear panel was satisfied. Such adjustment goes beyond plotting the frequency response on paper.

    After new substitute diaphragms are fitted careful measurement of the system and the network with all the drivers connected is required. Only then can re calculation of a revised network and measurement of the overall system to done correctly.

    Best to check these things out thoroughly once you buy them. That’s when the real journey begins.

    Why would you have to redo the networks?? People use Radians all the time and the JBL techsheets allow for driver substitutions. The substitute diaphragms are listed as 2421's and driver replacements if not serviceable are 2425's and coded as only slightly different replace both in a pair.

    Rob
    "I could be arguing in my spare time"

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    Talking

    Well it’s 8.40 pm in NY. Good evening.

    To answer your objections if you go to the trouble of detailed measurements of the drivers, networks and listening you will understand why.

    The three JBL diaphragms do in fact sound subjectively different and measure differently.

    Therefore they in fact have a different crossover network requirements as they do in fact have. The way they are integrated with the slot radiator is also different.

    The 4343 was voiced around its particular set of drivers. Having built 4343 clones myself and heard the 4343 in different homes l do understand these systems in detail.

    Perhaps you do not.

    It’s like everything. The harder you look the more you know. This was always there.

    You don’t have to accept this and plug and play.

    Finding the best sound out of a particular loudspeaker is about focusing on detail.

    Edit
    For those newish to the JBL legacy scene here is some useful background information. What l have posted above will then gel.

    The larger 43XX monitors went though several iterations from the early 70’s to the early 80’s. Some of these changes related to the move from Alnico to ferrite magnet drivers. In other instances the HF compression driver diaphragm was upgraded to a diamond surround. Initially this was an aluminium diaphragm then JBL changed to titanium. JBL also upgraded the mid cone driver in the 4 way monitors with a 10 inch driver.

    The table below is in the 4344 reference thread.

    As these variants were rolled out JBL did in fact update and refine the crossover networks to accommodate the characteristics of the driver / diaphragm changes. Greg Timber’s was tasked with a revision of the 4343B and the 4350 and other systems in the consumer range. The 4343B (ferrite magnet version) was succeeded by the 4344. The 4344 kept the same woofer (now the 2235H) and a new more refined mid cone was introduced called the 2122H. The diamond surround diaphragm was also introduced into the 4344 design with the 2421 compression driver. With these changes Greg Timber’s made significant changes to the prior network used in the 4343 numbered the 3143. The new network was numbered the 3144/3145.

    Fast forward to the mid 2000’s and these legacy four way system regained popularity.

    I was building a clone of the 4345 and l reached out to Greg Timbers for assistance with the crossover network. What eventuated were discussions around upgrading the 4343 to the 4344 driver compliment and network specifications. A lot of people jumped on that wagon and Greg Timber’s designed an equivalent diy 4344/4345 crossover network that forum members could build. Two other equivalent crossovers followed with minor differences.

    Now, if you have an original stock 4343 with the stock drivers you can elect to keep it completely stock. However, if you want to keep the 4343 system with the stock drivers you won’t find the stock 2420 diaphragms available. JBL in their now defunct replacement parts list do show the DR162426 titanium diamond diaphragm as a replacement diaphragm for the 2420 compression driver if you can still get them. It will go but the stock 4343 network is not optimised for that diaphragm per my outline above. The 4344 network was changed for the diamond surround diaphragm. How it works is quite different. The most recent four way version of these systems called the 4344mk2 with the ten inch mid cone has yet another different network with characteristics optimised for acquaplas diaphragms.

    So it matters enough for JBL to make sure that a particular driver and diaphragm combination has a good blend in the system in which it is used.

    So what about playing with alternatives? You can try the Radian diaphragms but again they won’t necessarily a be perfect drop in replacement for the 2420 diaphragm as far as the 4343 driver blend is concerned.

    I am proposing to cover this area of intrigue in more detail once my new website is up.

    Ian
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    Last edited by Ian Mackenzie; 12-19-2022 at 09:16 PM. Reason: Additional information

  15. #15
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    Well, he got them. He's been looking for a 43XX for a long time. He said the midrange had a bit of shout quality to them (as compared to other 43XX he's heard but that's based on memory and could have been the room). Also, the was some definite hiss or some such from the UHF, HF, and MF drivers even at a few feet away from the baffle. I suspect it could be due to the sensitivity of speakers but I've not experienced that with the 4333, 4343, or 4344's. In any case, he will have the drivers attended to. Thanks all.
    EJ

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