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Thread: JBL 4343 Renovation

  1. #16
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    Nameplate Positions

    It seems that photos of 4343s with grilles intact are pretty hard to come by. Worse, it seems that some grilles, like mine, have these plates in front of the tweeters. Unless JBL were doing some very sophisticated sound-engineering I doubt if this was intended. I am still searching for an authoritative photo of JBL originals. If anyone has such a thing I shoudl be very grateful to receive it. I would then try to get the exact positioning and publish the figures.
    I would never have believed such a "simple" question would be so complicated

  2. #17
    Senior Member DogBox's Avatar
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    Photo's

    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

  3. #18
    Senior Member 1audiohack's Avatar
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    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.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  4. #19
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    Nameplate Position .. the latest...

    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

  5. #20
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    Quote Originally Posted by DogBox View Post
    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

  6. #21
    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by georgebrooke View Post
    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!

    2ch: Oppo, Acurus RL-11, JBL 240ti, Heath AS101, Carver TFM-25,Von Schweikert VR4
    7: Oppo BDP103D, B&K, UREI 809A, JBL B460,

  7. #22
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    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.

  8. #23
    Senior Member 1audiohack's Avatar
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    Quote Originally Posted by georgebrooke View Post
    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.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  9. #24
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    Those nameplates

    Quote Originally Posted by 1audiohack View Post
    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......

  10. #25
    Senior Member DogBox's Avatar
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    Quote Originally Posted by georgebrooke View Post
    .... 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.......
    Hi Georgebrook, BonVoyage! Enjoy! ...and just remember: where ever YOU deceide to put the front nameplates- you can always take the grills OFF when you listen so that NOTHING get's in your way of listening enjoyment whilst reminiscing over the tour you've just been on!!!
    Lookforward to your safe return, and next post.

    Steve

  11. #26
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by georgebrooke View Post
    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
    http://www.audioheritage.org/vbulletin/showthread.php?6345-Tricky-mic-position-create-random-response-mesure&p=60625&viewfull=1#post60625

    Hi George,

    The boxes look nice.

    The tone frequencies are roughly centre to the pass bands of the mid, HF and UHF drivers so it was chosen on that basis.

    The purpose of the process is not to adjust the overall tonal balance in your listening roon but to balance the sensitivites of all 4 drivers so you then have a base line to make other adjustments.

    As there are 4 drivers (and not 2 as in a two way) its almost impossible to set up these systems by ear without getting the drivers sensitivity matched first.

    By a process of deduction you can negatively engineer a flat response from knowledge of the voltage drivers and drivers response as measured by JBL and the "cut" of each L pad as marked in the L pad plates.

    The fixed resister pads in the network were chosen to allow a +- range of adjustment for each driver with the L Pad of a known amount of dba.

    The only inaccuracy is in the resistive wire element of the L pads and the give in the plastic adjustment knobs and that is why we use a "meter" to measure the tone level at full level on the L pad and then adjust to cut the level a specific db to match zero position at discrete frequency points for the mid, HF and UHF Pad postions, ie - 4 dba, -3dba as the case maybe.

    If you have a lot of glass in your room or flat walls I would suggest Baxandall tone controls http://makearadio.com/tech/tone.htm

  12. #27
    Senior Member 1audiohack's Avatar
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    4343 Grill and Plate

    I left my note book so the detailed measurements will follow.
    Attached Images Attached Images    
    If we knew what the hell we were doing, we wouldn't call it research would we.

  13. #28
    Senior Member 1audiohack's Avatar
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    More detail.
    Attached Images Attached Images    
    If we knew what the hell we were doing, we wouldn't call it research would we.

  14. #29
    Senior Member DogBox's Avatar
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    More Detail.. And then Some!!

    Hey 1audoihack, B-E-A-U-T-I-F-U-L pictures, and detail. Seems amazing that those foilcal's mount using those small holes in the 1/2" angle.. and like you said- provision to be able to place them L or R, even with the top baffle rotated... plenty of angle pieces to utilise.
    Thanks Barry!

    DogBox

  15. #30
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    Crossover

    Hi Ian,

    I just saw your note explaining how you chose the frequencies etc. when setting up your speakers. Thanks for that information. Right now I am awash with possibilities but now that the speakers are domestically acceptable I am just listening to them for a while.
    I am still looking at the B4 approach, using the passive crossover components that you sent to me a long time ago.... leaving the original crossover untouched . I do get a lot of contradictory information from various people about the best way forward here.. pure passive, bi-amp, pure active, a mix and so on. A colleague is currently evaluation speaker cables based on CAT 7e and he seems to be getting quite excited about the results. it might be something I pick up on too.. when I stop the listening. We hope to publish the results of these listening tests later this year.

    Nice to hear from you again.

    best regards


    george






    Quote Originally Posted by Ian Mackenzie View Post
    http://www.audioheritage.org/vbulletin/showthread.php?6345-Tricky-mic-position-create-random-response-mesure&p=60625&viewfull=1#post60625

    Hi George,

    The boxes look nice.

    The tone frequencies are roughly centre to the pass bands of the mid, HF and UHF drivers so it was chosen on that basis.

    The purpose of the process is not to adjust the overall tonal balance in your listening roon but to balance the sensitivites of all 4 drivers so you then have a base line to make other adjustments.

    As there are 4 drivers (and not 2 as in a two way) its almost impossible to set up these systems by ear without getting the drivers sensitivity matched first.

    By a process of deduction you can negatively engineer a flat response from knowledge of the voltage drivers and drivers response as measured by JBL and the "cut" of each L pad as marked in the L pad plates.

    The fixed resister pads in the network were chosen to allow a +- range of adjustment for each driver with the L Pad of a known amount of dba.

    The only inaccuracy is in the resistive wire element of the L pads and the give in the plastic adjustment knobs and that is why we use a "meter" to measure the tone level at full level on the L pad and then adjust to cut the level a specific db to match zero position at discrete frequency points for the mid, HF and UHF Pad postions, ie - 4 dba, -3dba as the case maybe.

    If you have a lot of glass in your room or flat walls I would suggest Baxandall tone controls http://makearadio.com/tech/tone.htm

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