JBL 4343 Renovation

[georgebrooke]

Hi,
Years ago I promised a description of a 4343 renovation. It has taken me nearly 5 years to get anywhere with this... due to work pressure and the number of steps in my house. Neighbours who volunteered to help move the speakers from the garage to the house have aged but luckily some passing builders were talked into getting the speakers into the house.. but only after Rich (of Richluvsound) had performed some minor miracles.

The speakers were purchased (via eBay) from an ex-roadie of Pink Floyd. The initial problems were poor cabinet finish (in spite of the claim of a "piano finish") and rotted surrounds. Apart from putting them on wheels (since removed). They sat in the garage while I pondered active crossover, passive crossover, charge-coupled. Meanwhile I went ahead with building the electronics (Pass B5 buffer, F5 power amp, Crown K2 (purchase) bass amp).
Eventually I decided that I needed to get them into the house and that would not happen with them in their poor condition.

Having met Rich a few times I asked him if he would help on the woodwork. In this case, "help" turned into doing it all. He did an outstanding job as the attached before and after photos show. He has made his own thread on the work he did at http://www.audioheritage.org/vbullet...test-project-! One of my attached photos shows a close-up or the veneering and mitred corners. He has done a really superb job.

The situation now is that they are more than acceptable in a living room. Moreover, they sound ... even in their present un-tuned state so much better than my old L300s that I am sure that I am on the right track with these.

So, things to do.

1. Refoam the bass speakers. They had nestled in the house, not the garage, but that had not saved them from the ageing process. I have ordered kits from Rick Cobb. I have used his products in the past with good results.. and his method avoids the use of shims and dust cap removal.
2. Set up the balance of the speakers.. on 4-way systems not as easy as it should be
3. Listen to the speakers... on all kinds of music and take notes
4. Decide on upgrade priorities. From related threads I am awash with suggestions and ideas. My current thinking is to wait for a DIY version of the B4 crossover from our friend Nelson Pass and combine that with a rebuild of the remaining parts of the crossover. Given the similarity, it may even be possible to adapt the L300 crossover, recently redesigned by Nelson, for use in the 4343.
5. Preserve the original form and components of the 4343

If any one has comments or thoughts on what I am planning to do I am more than keen to hear them

I find it very satisfying to bring back top quality equipment to as near to its original state as possible. With this sort of equipment I am not so much the owner as the keeper, for now. Remember the Patek Philippe advert. "You never actually own a Patek Philippe. You merely look after it for the next generation". Well, if the next generation have big enough living rooms this might just be true!

[Lee in Montreal]

Nice restoration work.

[DogBox]

Hi georgebrooke,
Have you seen the photo's from the library brochures on the 4343? The library has the 4343 and the jblpro.com/vintage has the 4343B-both have pictures on the second page showing the nameplate where Bo said they were placed. Not a real good shot for accurate placement positioning, but let's you know were they were put originally. Hope it helps...

Steve

[georgebrooke]

Hi georgebrooke,
Have you seen the photo's from the library brochures on the 4343? The library has the 4343 and the jblpro.com/vintage has the 4343B-both have pictures on the second page showing the nameplate where Bo said they were placed. Not a real good shot for accurate placement positioning, but let's you know were they were put originally. Hope it helps...

Steve

Hi Steve,

thanks for reminding me about page 2 of the brochure. I still doubt if JBL really intended to stifle the tweeters with a nameplate, so I'm now brooding on the subject, again. The phrase "Get a life" springs to mind :-(

George

[hjames]

Hi Steve,

The phrase "Get a life" springs to mind :-(

George

Not at all - you HAVE a life!
you have a pair of GORGEOUS monitors,
be sure you enjoy the heck out of them -
play some good tunes, or discover something new -
that's the whole point of all this dancing!

[4313B]

It takes a helluva lot more than some little strip of aluminum to stiffle a slot. They'll just burn a hole through that thin foilcal.

[1audiohack]

Hi Steve,
I still doubt if JBL really intended to stifle the tweeters with a nameplate, :-(
George

They didn't and they don't. Inside the grill frame behind the cloth are small metal tabs that the badges clip to/through. They can be attached left or right in mirror image as to not shade the tweeter with the box oriented either vertically or horizontally.

I have the dimensions and pictures but posting them will have to wait until I get home Monday.

[georgebrooke]

They didn't and they don't. Inside the grill frame behind the cloth are small metal tabs that the badges clip to/through. They can be attached left or right in mirror image as to not shade the tweeter with the box oriented either vertically or horizontally.

I have the dimensions and pictures but posting them will have to wait until I get home Monday.

Hi,
i am looking forward to seeing your definitive photograph of the proper positioning of the plates. However, by the time they arrive, Monday, I shall be on a boat just off Portugal and heading to Spain, France, Sicily, Italy and Croatia in that order. Hence JBLs will not be top of my list for the next three weeks. But when we get back......

[57BELAIRE]

Outstanding!

I am currently involved in a similar project with a pair of 4350's and after some discussion and following numerous threads on this forum and other's, I've decided to keep them as original as possible with the exception of charged coupled networks.

They had been stashed in a warehouse for some years and before that were in a basement party room. I hope to bring them back to their former glory...well, almost. The walnut veneer is passable for now and the original drivers (except 2202H mid-bass) are surely roadworn but still pack quite a whallop.

After seeing yours, I'm fired up again to complete this project even more than ever

Your efforts are truly inspiring!

[georgebrooke]

Outstanding!

I am currently involved in a similar project with a pair of 4350's and after some discussion and following numerous threads on this forum and other's, I've decided to keep them as original as possible with the exception of charged coupled networks.

They had been stashed in a warehouse for some years and before that were in a basement party room. I hope to bring them back to their former glory...well, almost. The walnut veneer is passable for now and the original drivers (except 2202H mid-bass) are surely roadworn but still pack quite a whallop.

After seeing yours, I'm fired up again to complete this project even more than ever

Your efforts are truly inspiring!

Hi,

it seems that your speakers had a troubled start just like mine... starting out in a garage. I really would encourage you to finish them.. but always be able to get them back to the original state regardless of changes that you might make.
In doing all this work my speakers are back to the original JBL "slam" but sadly they have lost the characteristic JBL smell. It used to be that I could recognise JBL speakers at 20 paces. No longer with mine. I think Rich cleaned them out properly!

[hjames]

They do look gorgeous now - Rich did outstanding work ...

and if you want the old "JBL smell" back, I imagine you could always spill a few pints on or around it and
get that back too, tho it'd be a real shame to muss that fine wood finish!

Hi,

it seems that your speakers had a troubled start just like mine... starting out in a garage. I really would encourage you to finish them.. but always be able to get them back to the original state regardless of changes that you might make.
In doing all this work my speakers are back to the original JBL "slam" but sadly they have lost the characteristic JBL smell. It used to be that I could recognise JBL speakers at 20 paces. No longer with mine. I think Rich cleaned them out properly!

[georgebrooke]

Hi,

can anyone point me to a clear procedure for setting up the L pads on the 4343s? I have a sound meter and access to a signal generator, but I am not sure of the frequencies to choose nor of the levels to aim at. In other words, not a clue!

Today the new foam surrounds for the bass units arrived. And just in time too... as a bass-heavy track left pieces of foam scattered over the carpet. I am expecting the bass to get even tighter with the repair fo the surrounds, but even now it is considerably tighter than my memory of the L300s.

[BMWCCA]

Hi,
can anyone point me to a clear procedure for setting up the L pads on the 4343s? I have a sound meter and access to a signal generator, but I am not sure of the frequencies to choose nor of the levels to aim at. In other words, not a clue!

One method: Run a full frequency range, record SPL at each frequency and aim for a flat response (same level) on every frequency you run, with the meter in the spot your ears would be. (You'll probably need at least a third-octave EQ to do it accurately depending on your room).

Another: Adjust the L-pads in small increments and listen. Set it the way you like it. Treat them like tone controls to some extent. They're your ears and it's your system.

One more: Assume that god knew what he was doing; do away with all tone controls and keep the L-pads at zero. Any audiophile will agree.



I used a Rat Shack dB meter and a compact pro tone generator with a full-spectrum sweep. I put the meter on a tripod and actually found my room reasonably flat without any adjustment. It was more reassuring than it was illuminating, but my room is well-damped, pretty small, with low ceilings and equal openings at either end/side, with enough "stuff" and furniture to kill just about any resonance. I do have a third-octave EQ in every system but generally use it for low-level listening compensation only.

[1audiohack]

Hi George and DogBox;

I am currently visiting a friend who has a one owner, near pristine pair of 4343's as his home mains. I left the camera at the shop last night but I will before I leave this weekend collect the dimensional information and pictures you are asking for, please stand by.

Barry.

[georgebrooke]

Hi,
well as information on the position of these nameplates continues to pour in, it seems there is no real resolution. I have come across photos showing the nameplates positioned at the top as well as at the bottom of the grilles.

Although the top position is persuasive, being shown in a JBL brochure, I cannot believe that it is intended. The plate passes across the centres of the two tweeters. This is unorthodox to say the least. So, unless someone can provide evidence that this is an intended sound modification .. a crude type of lens for example.... I think I have to dismiss top mounting, even if it does look nice.

So, positioning at the bottom is not so difficult. The brackets that JBL provide do have to be moved (they provide brackets for top mounting for vertical use, and side mounting for horizontal use) to the bottom of the grille. They only questions then is to left or right justify , or to provide mirror image. Since none of these choices can affect the sound it is a purely cosmetic decision. The brackets control the height of the nameplate. There is about 18 cms. of movement possible in left-to-right positioning. Feel free to choose, as we seem to be leaving JBL's mounting decision anyway.

I am still open to persuasion on this... if there is compelling evidence to support the top position. Melanie thansk for the many answers and PMs on this subject.

George