Should I buy a pair of JBL 4343?

[Ian Mackenzie]

Without a better high resolution pic l think the midrange driver might have been reconed because the dust cap glue suggest this is the case. Note the dust cap requires removing and replacing with either the original or a new dust cap when reconed or refoam as the voice coil needs a shim to centre the coil in the gap.

After market 2121 cone kits are available. I have not compared them to a factory recone

What some people to us put the 2123H in which can be acquired off Ebay (they are quite common and a superior transducer)

Some reworking of the network is required but you end up with a better spec system if you also replace the compression driver diaphragm. This is path of the course in the improvements mentioned earlier.

The original networks are specific to the drivers in the 4343, the 4344 and the 4344mk11.

This includes not just the midrange but the compression driver diaphragms. The JBL D16R2420 (aluminium in the 4343,4343b), D16R2425 (titanium 4344) and the Acquplas dusted D26R2425 exhibit different frequency response signatures that require specific voltage drives.

[macaroonie]

The cones look a bit sus to me mainly because of a slight shiny appearance , not only on the cones but also on the surrounds.
Usually cones of this age are very dull looking.
However the OP seems to have a deal with the seller ie !k euro down and 1k later if he is satisfied that all is well.
If everybody plays ball this will work out and we will have a new member to guide through the refurb.

I say go for the deal , lets have a look at the drivers , and it seems he is in touch with Guido so help is on hand.

Good luck Kai.

[RMC]

Hi Kai,

Re: "...to check the drivers - is this possible from the front or do I have to unscrew the baffle?
The cone drivers you can remove from the front. As for the compression driver and tweeter you may very well have to remove the top front panel since there are separate chambers for 10" and 15" drivers, so there seems to be no access to high frequency drivers through a mid or woofer hole for example because of those separate chambers (see 4343b data sheet, enclosure section).

RE: "He says that he only could recone the bass drivers with original parts, all other drivers not with original parts, the midrange not all. Is this common sense? And is this the end of the story or has somebody expierence with 3rd party replacements which work equally well?"

This is the cruel reality of purchasing older speakers (1980 or so)... Original parts aren't available forever. And aftermarket parts quality varies from good to bad and ugly... It will work, the issue is how well? Unfortunately, its not written in the sky which is what, though experienced speaker repair people may know more than others about that.

As for aftermarket parts maintaining same specs and performance as original ones, this remains a big question mark. Welcome to the world of older speaker restoration. Regards,

Richard

[RMC]

RE post # 17

"That all is well" and "I say go for the deal" seems easy to say when you're not the one who has to go through all the work involved AND PAY for it! Regards,

Richard

[RMC]

Hi Kai,

An afterthought, and a possible money saving idea for you. I generally try to think about value for my colleague's money instead of just easily throwing good money at a problem.

If, and only if, the cones on the the woofer and mid are actually original JBL stuff and in good condition, it may be worth it to have these re-surrounded properly only (not reconed $), thereby saving a good amount of cash which you may well need anyway for the high frequency devices as mentioned by another and crossovers... That should be done with driver model specific material instead of simple generic surrounds to increase the chances of driver similar performance afterwards. This idea is based on the following.

D.B. Keele has indicated, in his sixth-order LF alignment paper, "The relative insensitivity of vented-box frequency response and cutoff frequency to changes in the driver's suspension compliance..." (1974, P. 354).

Ten years later, Electro-voice reaffirmed that idea in these terms: "... Thiele's model shows that system performance is relatively insensitive to variations in certain speaker characteristics, e.g. suspension compliance." (E-V, Pro Sound Facts, No. 7, Oct. 1984, P. 1).

What this means in practice is that even if new surrounds aren't perfectly identical, within limits, to original ones in terms of compliance (assuming spider is good), then the chances of noticing a difference or deterioration of sound from original ones would be slim. This may be worth a try.

One fellow here even tried it on JBL 15" woofers with Butyl Rubber surrounds (there's a thread here on this) and he was delighted. He added he could not hear the difference from before and after. Food for thought...

Regards,

Richard

[ivica]

Hi Kai,

An afterthought, and a possible money saving idea for you. I generally try to think about value for my colleague's money instead of just easily throwing good money at a problem.

If, and only if, the cones on the the woofer and mid are actually original JBL stuff and in good condition, it may be worth it to have these re-surrounded properly only (not reconed $), thereby saving a good amount of cash which you may well need anyway for the high frequency devices as mentioned by another and crossovers... That should be done with driver model specific material instead of simple generic surrounds to increase the chances of driver similar performance afterwards. This idea is based on the following.

D.B. Keele has indicated, in his sixth-order LF alignment paper, "The relative insensitivity of vented-box frequency response and cutoff frequency to changes in the driver's suspension compliance..." (1974, P. 354).

Ten years later, Electro-voice reaffirmed that idea in these terms: "... Thiele's model shows that system performance is relatively insensitive to variations in certain speaker characteristics, e.g. suspension compliance." (E-V, Pro Sound Facts, No. 7, Oct. 1984, P. 1).

What this means in practice is that even if new surrounds aren't perfectly identical, within limits, to original ones in terms of compliance (assuming spider is good), then the chances of noticing a difference or deterioration of sound from original ones would be slim. This may be worth a try.

One fellow here even tried it on JBL 15" woofers with Butyl Rubber surrounds (there's a thread here on this) and he was delighted. He added he could not hear the difference from before and after. Food for thought...

Regards,

Richard

Hi Kai,

I think this is good suggestion.
Regards
Ivica

[Ian Mackenzie]

The local Jbl service agent in Germany would be able to confirm that with a sweep using a Woofer Tester or other Test apparatus such as Liberty Audio Suite. Most agents offer the service of new surrounds these days.

[martin_wu99]

... me again ...

As suggested, I contacted Guido from Behringer Electric, and it does not look good. He says that he only could recone the bass drivers with original parts, all other drivers not with original parts, the midrange not all. Is this common sense? And is this the end of the story or has somebody expierence with 3rd party replacements which work equally well?

Hi kai,don't think too much,just ask the seller again to send you hi res. pics of all drivers,the fronts and the backs,then it is easy to judge(this need the seller to dismentle all drivers),this is a rightful claim.
if some drivers are not original,tell the seller directly,and ask him to reduce the price,make sure this is a good deal.if he is not willing to reduce the price,think over if it is still a real bargain.
BTW,except the 2121h,other drivers are not so difffcult to be reconed or replaced

[Robh3606]

If, and only if, the cones on the the woofer and mid are actually original JBL stuff and in good condition, it may be worth it to have these re-surrounded properly only (not reconed $), thereby saving a good amount of cash which you may well need anyway for the high frequency devices as mentioned by another and crossovers... That should be done with driver model specific material instead of simple generic surrounds to increase the chances of driver similar performance afterwards.

If they are indeed original cones I wouldn't be to quick to do that. Whoever re-foamed them was way to generous on the glue and if they were recently done it is going to be very hard to cleanly remove the foam without damaging the cones. The 2121 cones are thin and light and if the FS is screwed up it simply won't matter in a sealed enclosure crossed over at 300Hz. If you tear or delaminate the cone your done. Better off just letting them age and re-foam them again down the road.

The 2231/35 all you need to do is verify Fb with a simple impedance sweep to see where it is and again if reasonably close within a Hz or 2 just leave them be. The 2231/35 cones are much heavier but the will peel apart if the glue and foam is fresh.

I recently did re-foams on my 2235 and 2122 drivers in my 4344 clones and you really have to be careful even when the stuff if falling apart as the 2122's are so thin it takes very little to damage the cones. When you re-foam the glue stays on the cone, you can't get it off only the foam comes off.

Rob


http://www.audioheritage.org/vbullet...d-Step-by-step

[Ian Mackenzie]

Yes they are delicate.

Btw l thought we had a forum member in Spain.(alpina)
Perhaps he can be of assistance given all the help he’s received recently.

[more10]

The most important part is the cabinet. The drivers are approximately worth 1600€ if in good shape. The bass and midrange are rare. I believe a pair of 4343B in good condition are worth 4000€. So a pair of good cabinets are worth at least 2000€, if my calculation is correct.

This is a good deal, if it is for real. You will have to make shure the cabinet is original JBL and not a DIY thing. You will have to make shure the cabinet is nice.

If the cones and voice coils are ok, a good repair shop can replace the foam and the spider. As long as they sound without any bad sounds, they can be refurbished. If not you will have to look for second hand drivers.

It could be a scam. You have to go there to make shure the cabinets exist. Strict pay on delivery!

Mårten

[Kai]

Don't want to be slimy - but thank you so much to all of you! The learning curve was very steep for me the last week.
And as fas as the purchase of these speakers on Tenerife are concerned - this seems to be cancelled. As mentioned, we agreed on half payment upfront and the rest upon arrival of the speakers. I told him that I'd pay as soon as I have pictures of the ready-to-ship pallet plus a written confirmation of the forwarder that they in possession of the consignment. I haven't heard from him since.


However, this does not worry me too much. Now, that I have licked blood, I'm currently in negotiations with a seller in Torino, Italy. Still 15 hours to drive, but at least manageable. He has no idea about the speakers, bought them himself 3 years ago, didn't change anything since, and invited me to come personally. Sounds much better than my first try.


From the pictures I'd guess that the midrange again had been re-foamed/-coned, but I assume this will be the feat of every 4343 one can buy today.
I'll have a telecon with Guido tomorrow, I'm a little worried about the 2121H since I believe this is most important unit in the system and defines the whole character of the speaker.

[ompdiburi]

Just my opinion, to be in Europe 2000€ is a very good price, but it suonds strange to me that the seller accept to receive the second half of the payment after you receive the speakers, be sure that he really have the speakers, ask him a copy of his I.D. and be carefully in general, good luck!
Giuliano

[RMC]

Hi Kai,

RE: Post # 24

RE: "... if they were recently done it is going to be very hard to cleanly remove the foam without damaging the cones.(...) "Better off just letting them age and re-foam them again down the road." Pretty clever idea in my view, just in case. Quite possible refoam done recently in order to sell the boxes... The drawback is that you have to keep looking at the damn sloppy job previously done for a while, unless putting the speaker grille on... Though still better than damaging the cones with too early refoams: "all good things come to those who wait" then...

BTW I was thinking these would be sent to Guido to do that work (he's presumably competent), not to do it yourself. Additionally, since it was mentioned here by the same fellow (who also rightly said HF devices may need some love too) that 2231 recones are no longer available, I assume when Guido said he could only recone the woofers with original parts then he probably had in mind 2235 recones (not 2231). Oups, another bit of "non-originality", but then one does what he can. 2231/2235 T/S not the same but not too far off, compliance quite different but less sensitive or critical to performance, as shown by Keele/EV. EDIT: See also Bullock on P.24.

On the other hand the same fellow told us in another thread (Deeper bass...) that 2235 recones were getting more difficult to find... This not to show any issue here, but rather to illustrate this is getting like the dog chasing its tail for older speaker restoration with original parts! Moreover, It does tend to show the more you wait here the less original parts your likely to find... NOT "all good things come to those who wait" in matters of "original" recones availability though... So a decision has to be made about wait (refoam) and don't wait much (recone woofers).

RE: "When you re-foam the glue stays on the cone, you can't get it off only the foam comes off." I certainly cannot agree with that statement however. I have done it (removing the old glue) on back of cones of my 2214H with Isopropyl Alcool 91% sold at Wallmart (not the usual 70%), as indicated by Simply speakers, and it worked fine, though a monk's job! I guess i'm more courageous or work harder than others then. I didn't want to leave that sticky stuff there and add more on top of it to glue the new foams on the back side of cones, even if it can't really be seen when driver mounted. For two reasons that follow.

First, I would have felt like doing a sloppy job and I like my things proper, as original as I can.

Second, since I cut the dustcaps 90% around just above the old glue line, except where the wires are, to also remove foam rot inside the drivers (another monk's job), I felt the dustcap's new black glue line would already add a little cone mass and I didn't want to add more of that on the back side of the cone where surrounds are glued. Plus I preferred to keep, if possible, the original dustcaps, which I did.

EDIT: On the driver frame where the other end of the surround is glued, with my cleanup I'm down to the black original paint all around, not a drop of old glue nor anything else left, just the black paint with metal under.


Naturally, soaking the cone's edge with 91% alcool is a no go, to avoid defeating its chemistry. So I put alcool on a soft rag and using a finger in the rag went around patiently and slowly MANY times avoiding touching non-glued surfaces, turning the rag with again some alcool, even using cotton swabs with alcool for hard to reach places. Yes, its time consuming but I wouldn't have it any other way (i.e. as original as I can). Proud of job done!

Regards,

Richard

Edit:

Still have another pair of drivers to refoam, this time small woofers I like, if I can find proper surrounds locally. Then, hopefully, refoaming work is over for ever?

I've been trying for a few years now to avoid foam surround drivers like the Ebola disease, running away from them. They don't last long enough for me and way too much work to refoam, when doing it properly...

Among the six pairs of woofers I purchased in the last four years, NONE has foam surrounds. Only rubber or treated cloth surrounds, that's it.

[Triumph Don]

What is the price in US dollars? If both woofers work, they can be re foamed to work, sound, and look fabulous. I have done many over the years-just need very sharp tools [razor blades, exacto knives] good eyes steady hands, and patience. The real tough ones have already been "repaired" with anything from silicone to electric tape. These look to be perfect candidates. Looneytune2001 on eBay has the best kits IMO.