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Thread: Thoughts on these 4343 drivers

  1. #16
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    Great. They are a really fun system to own.

  2. #17
    Administrator Robh3606's Avatar
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    "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."

    Hello Ian

    Yes they do especially in a 2 way where you can clearly hear the differences. That said the 4343 is a bandwidth limited system where differences will not be any where near as obvious. Especially since the main differences are HF extension that are covered by the 2405.

    Rob
    "I could be arguing in my spare time"

  3. #18
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    Do you remember the sea shells sound people were claiming from those slant plate lens on the horns. A few improvements here and Giskard was whistling dixy about them….

    The 4343 ran out 6/ db per octave on the ragged edge. Full range the 2420-2307-2308 does go out flat a way but it narrows into a torch beam. The 2405 is the bat slayer or should l say the mosquitoes repeller.

    In contrast 4344 cuts the 2425-2407-2308 12/ db per octave. The 2405 comes on far less aggressively. It’s seemless.

    The 4344mk2 again let’s the dusted 2425-2307-2308 run out at 6/db per octave. Less glare. The 2405 adds air and shimmer.

    It’s hardly surprising the Japanese has a sort of love hate relationship with the 4343. On the one hand they worshipped it. On the other hand they could imagine ways to improve it. JBL came to the party.

  4. #19
    Member VinylGroove's Avatar
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    Quote Originally Posted by club900fe View Post
    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.
    I experienced some anomalies like this at first with mine. Deoxit on the L-pads and the biamp roatary swtich, then working them back and forth with a penny 20 times took care of it. If your sources/pre/amp gear has hiss or noise, it's going to be magnified by these highly sensitive speakers for sure.

    I found that using a combination of the small deoxit bottle with needle on it and the regular spray can with the straw tube helped me get it inside the Lpads much better than using either alone. YMMV.
    https://www.amazon.com/gp/product/B0000YH6F8/

  5. #20
    Dang. Amateur speakerdave's Avatar
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    Well, here’s hoping your friend gets the sound he wants from those speakers.I listened to a pair of 4345 for a few years.As received, the stock CD/horn setup didn’t work for me; no doubt a tired diaphragm was involved, but I do not know if a new one would have fixed it. I ordered some new 2421 diaphragms, but never used them. I found two other solutions; one of them, the one I settled on, was a strictly seat of the pants deal—to substitute a TAD beryllium driver. They are 8-ohm and have quite a different frequency response from either a titanium or aluminum driver, but somehow it worked. I’m aware of a few other people who did the same thing and found it equally satisfactory. I bought used 2001’s on eBay and luckily they were OK; it would be even riskier to do that today because the diaphragms are no longer available. The other people who found this experiment worked out bought new 2002’s. They are still sometimes available, but are very expensive at three grand retail each. I’m not aware of anyone measuring one of these setups. I used a lucky dime to set the levels, but didn’t measure the result. That would be like questioning happiness, wouldn’t it? Who does that?The other solution was a close second; I almost settled on it because it seemed more rational on the face of it. I found that whereas the 2441 on a 2311 was too big to go into place because of the dog box for the 2122 10” midrange, a 2450 did fit. The relevant details of the space may not be the same in the 4343. I installed 16 ohm dusted titanium diaphragms and found it quite satisfactory. The difficulty here is finding the 2311 horn. There is a Selenium horn some say will work but would require a cabinet hack, which you should not do. I haven’t tried it. It would also require a taller 2308.Giskard/4313B built a 4345ish speaker substituting a 2123, a 2445 and the revised 4355 network (no tapped inductors).According to one of the forum founders, the 2450 driver was originally developed for the Truextent beryllium diaphragm and could be fitted with the one available from Radian. I would expect that substitution to require a revised network. Ian should be able to hammer that out.2-ways, 3-ways, 4-ways all have their beauties and compromises. The bandwidth limiting in a four-way is definitely a real value. JBL has dropped support for the lovely big blue-faced four-ways; there may be stashes of key ingredients in certain places, but I am not privy. The viability of those systems may entail a careful update.
    "Audio is filled with dangerous amateurs." --- Tim de Paravicini

  6. #21
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    Hi Speakerdave,

    That’s quite a journey,

    The beauty of these 4343-4344-4345 designs is that they are a diy tweaked delight.

    I too have had an interesting and storied journey.

    A few tips.

    As Speakerdave noted it’s best to look the how your compression driver is going? Give it a health check. Ken Haerr at Upland Loudspeaker Repair is an expert at cleaning and Re fleshing compression drivers. That can make a considerable difference to your listening impressions.

    Next. Those Mylar caps used in the stock crossover really muffled the potential of these systems. The drivers have significantly more potential than the stock crossover network allow. Bypass the lossy Biamp switch and install some good quality binding posts. When it comes to high resolution sound good terminations with large contact area makes a difference. Pick your mark with capacitor options in your new crossover network. Charge coupled a nice but may not suit all budgets.

    After that it’s time to settle in to your favourite tunes.

    Once you become more familiar with the 43XX it’s time to consider adjusting of those L pads. In my experience adjustment of the L pads is an important performance gateway to realising just what these systems can do. The procedure is detailed and there are a couple different approaches. You can perform a spot frequency spl check on each drive and dial back the level with the L pad by a known amount. Or you can use REW. A YouTube of this in on my long to do this. Done carefully you end up with a vastly improved tonal balance and left & right level matching. This improves the sound stage and provides an immersive feeling of being bought closer to the music.

    As to compression driver diaphragms l would spend time appreciating the stock diaphragms. Find out what’s installed after you have them serviced. Different alternatives are available. They generally will fit the compression driver. But to ensure they are correctly fitted seek help from someone like Ken Haerr if you are not familiar with changing out diaphragms. You will subjectively hear a difference from one after market diaphragm to another and the JBL DR162426 diaphragms.

    There are TWO reasons for this. The metallurgy and suspension components are different and the frequency response of each diaphragm varies. Yes it does. This can be dealt with by small adjustments to the L pad or you can EQ out the differences with your system EQ if you use one. Adjustment of the horn and slot filters is a specialised option. If you have a graphic EQ or Dirac in your receiver or pre processor you can dial in your system. I know of a long standing member who has done this with excellent results. You can fine some good deal on a 31 band Klark Teknik EQ online. They look cool and are an interesting conversation piece over a beer.

    Acquaplas coated JBL diaphragms are a very nice option that is less invasive than installing a large format driver. To optimise the tonal balance requires adjustment of the crossover components in the horn and slot radiator crossover filters. Ken Haerr can assist with acquaplas coated diaphragms. If you wish to go the large format compression driver route it’s expensive and requires horn and slot crossover network filter adjustments. They offer lower 2nd harmonic distortion at higher frequencies and greater dynamic capability. The wider two in throat on the large format compression drivers can impact on the high frequency dispersion and this is where network adjustments can assist. It’s a detailed specialised area that requires measurements and re calculation of the network filters. If you are interested in that rabbit hole l can be reached via the link below.

    I would recommend focusing on getting the most out of what you have before embarking on changing too many things at once.

  7. #22
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    Lightbulb

    Quote Originally Posted by Robh3606 View Post
    "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."

    Hello Ian

    Yes they do especially in a 2 way where you can clearly hear the differences. That said the 4343 is a bandwidth limited system where differences will not be any where near as obvious. Especially since the main differences are HF extension that are covered by the 2405.

    Rob
    We all have a different perspective on reality.

    Throughout the evolution of these 4 way systems JBL made improvements to the diaphragms and applied different crossover EQ and crossover slopes to the horn compression drivers.

    In layman’s terms a skilled loudspeaker engineer can create driver EQ within a crossover network. This was done by JBL in the horn crossover filters of each of the 4343, 4344-4345 and the 4344mk2 systems so that the drivers blended correctly.

    This is as much an art as it is a science. JBL applied acquaplas coatings on some of their compression driver diaphragms including that in the 4344mk2 for a reason. What it does is not easy to measure in detail but it does change the sound of the horn. It’s not subtle.

    The trick is though to then reassess the whole system subjectively and look at how the horn will best blend with its different qualities between the mid cone and the 2405.
    An impedance control network was added to the compression driver with a different EQ tilt and the horn extends out further than in the preceding 4344 system. The result is not just a smooth blend but the horn now has a very similar timbre to the mid cone. The 2405 transition over from the horn is more coherent. You must use the 4344mk2 network with an acquplas dusted JBL D8R2425 diaphragm for the best results. In the 4344 equivalent network the acquaplas diaphragm sounds dull or muted. It just does work not as well as the 4344mk2 network.

    Rob is perhaps a bit more reserved than me. I am not backward in coming for when l discover a new insight into the JBL sound. I have been told l sound like a JBL engineer…Lol. I am a curious person who looks into how things work and l go after it. I built my first clone of a JBL 4343 back in 1980. At the time l wrote to JBL at Northridge for details of the 4343 passive crossover network. The late Gary Margolis wrote back to me with a nice letter explaining he was unable to assist and recommended l actively crossover my 4343 clone. Gary was an applications engineer at the time.

    https://fohonline.com/featured/in-me...lis-1941-2022/

    Moving forward in 2005 l penned a thread on upgrade options for the 4343 to a 4344 with Lansing forum member Porschedman. Rob made the comment are you sure people will be able to hear these upgrades?

    https://www.audioheritage.org/vbulle...4343-to-a-4344

    https://www.audioheritage.org/vbulle...o-4344-upgrade

    The rest is history….. Lol .

    Since then more 4344 & 4345 upgrades and clones have been completed than probably any in any other medium format monitor in history. Many people including Giskard and Greg Timbers contributed to that renaissance. Rick another Lansing forum member who l have met in Ohio formed Kenrick Sound in Japan with Kenji and they started making clones of a range of JBL monitors and to this day continues to provide upgrades. I still keep with Kenji and we share a mutual respect.

  8. #23
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    Good stuff, all. Given the holidays, he says it may be a while before he is able to get the drivers looked at and serviced. In the meantime, he is enjoying them as is. Hiss and all!
    EJ

  9. #24
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    Refer to post 22.

    A snippet of new measurements on all things JBL

    Measurements are one thing. But the truth is in the listening 👂

    (2426 acquaplas is brown)
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  10. #25
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    For all those JBL fanatics playing their 4343 legacy systems here is a simple tweak.

    It’s a lot less effort than removing that upper baffle.

    Grab a swivel office chair and adjust your listening height so your ears are level with the bottom of the slant plate lens. (Most people listen to the horn on axis right. Just like being on axis with the tweeter of a two way loudspeaker.)

    This listening height may offer an improvement in coherence in the mid and horn outputs depending on your listening environment.

    Try it and let your ears be the judge.
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