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Thread: JBL 4343 Renovation

  1. #1
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    JBL 4343 Renovation

    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!
    Attached Images Attached Images     

  2. #2
    Senior Member Lee in Montreal's Avatar
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    Nice restoration work.

  3. #3
    Senior Member 57BELAIRE's Avatar
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    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!
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    OPUS POCUS

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    Quote Originally Posted by 57BELAIRE View Post
    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!

  5. #5
    Heather [Senorita member] hjames's Avatar
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    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!

    Quote Originally Posted by georgebrooke View Post
    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!
    2ch: Oppo, Acurus RL-11, JBL 240ti, Heath AS101, Carver TFM-25,Von Schweikert VR4
    7: Oppo BDP103D, B&K, UREI 809A, JBL B460,

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    Question Setting Up the 4343s: Help / advice wanted

    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.

  7. #7
    Senior Member jbl_daddy's Avatar
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    I have toyed with the idea that you just completed, my wife says she still will not let them in the family room. Lucky she likes the 250ti's... In her defense she puts up with more than i could.
    Well why not it's just one more pair...
    4340's and 250ti's what an odd pair...

  8. #8
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by georgebrooke View Post
    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.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  9. #9
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    <snip>,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!


    Ian MacKenzie posted a "KISS" procedure ( quite a few years back ) that used an SLM/SPL meter ( along with certain test tones ) to balance the Lpads of these big 4-ways . It was apparently quite effective .






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    Setting those L-Pads

    Quote Originally Posted by Earl K View Post


    Ian MacKenzie posted a "KISS" procedure ( quite a few years back ) that used an SLM/SPL meter ( along with certain test tones ) to balance the Lpads of these big 4-ways . It was apparently quite effective .





    Hi,
    I did see Ian's post.. but I could not understand why he chose the frequencies that he did and some of the instructions were a bit (IMHO) ambiguous.
    Anyway, the plan is still to listen for a while.. fix the foam surround (which arrived from the US in just a few days after ordering) and let the system settle. Then start a procedure for balancing. Ultimately I suspect it will be a procedure followed by fine tuning according to ear-preferences. We shall see. This is just the start of a long job.

    Strangely this morning I noticed the JBL smell reappearing. Perhaps the bass notes have shaken it out of the wood but it is definitely there. It could make a nice aftershave :-)
    I am still impressed how non-hi Fi it all sounds.. big, relaxed and nimble!
    Thansk for all the advice

  11. #11
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    L-Pads

    Quote Originally Posted by BMWCCA View Post
    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.
    Thanks for the above .. I think they are the start of a procedure that I could use. Re. the involvement of God in this.... you can give him a helping hand by starting from a clear starting point. This may sound stupid, but if you have one of those Water Pic devices then , using warm water, you can give yourself an ear syringe. I promise you that for around 30 seconds (until clever-old brain adapts) you will hear detail in your music like you have never heard before. Don't use cold water.. apparently this is used to test pilots for a tendency to vertigo and it could trigger an attack. Still, even if you are on your back it will still sound pretty amazing.

    George

  12. #12
    Senior Member spkrman57's Avatar
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    Great thread

    Nice work!

    Regards, Ron
    JBL Pro for home use!

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    JBL 4343 Grilles and Setup

    Hi,
    I seem to have answered my own question regarding the set-up. A colleague appears to have a pair of "golden ears" and infinite patience and went through an extended adjustment session with me on a variety of music. We arrived at a setting which we both appreciated. Whether this is "right" probably does not matter.. they sound glorious.

    There is another small problem. Eagle-eyed readers might have noticed something odd about the grilles shown in my photographs above. The JBL model number plate is fixed to the top of the grille and extends in front of the tweeter and super-tweeter, doing nothing good to the sound at all. I have so far not been able to find the recommended position for the JBL model-number plate, except to guess that it should be at the bottom of the grille. Can anyone provide me with photographs and / or measurements of the correct position of this plate. I really would like to get it right when I do move it. Most photographs that I have come across avoid showing JBL grilles, in favour of showing off those impressive drivers. Thanks for the help

  14. #14
    Senior Member 1audiohack's Avatar
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    I can send you a picture and measurements in a couple of days of an original near pristine pair owned by a friend but I can tell you in the meantime that the plates are top left and do shadow the 2405 and 2308. Isn't that odd??
    If we knew what the hell we were doing, we wouldn't call it research would we.

  15. #15
    Senior Señor boputnam's Avatar
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    Quote Originally Posted by georgebrooke View Post
    ...Can anyone provide me with photographs and / or measurements of the correct position of this plate. I really would like to get it right when I do move it.
    Per my pm, my 4345's are top-left, as per Barry's post (1audiohack) for both cabinets, R or L, JBL logo always on L side (like the Union Jack on the US Flag...).
    1 1/8" below top of grill
    2 1/2" inside left edge of grill
    But, these are 4345's, and not the cabinet in question.

    Quote Originally Posted by 1audiohack View Post
    I can send you a picture and measurements in a couple of days of an original near pristine pair owned by a friend but I can tell you in the meantime that the plates are top left and do shadow the 2405 and 2308. Isn't that odd??
    Not the 2308, surely (unless your vanes are angled upwards...? ). On the 4345 there is no obstruction to the 2405; on the 4343, from the pictures here, it looks like only the very top'ish area of the 2405? But remember this is a horizontal-dispersion wave guide. I think we need some pics from un-retouched 4343's to see what the makers intended - maybe that logo plate is shifted upwards....
    bo

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