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Thread: L65 no thumb

  1. #1
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    L65 no thumb

    I’m 41. Pops bought these L65, back in the late 70’ies. I grew up with them, know their sound, has anyone come across the phenomenon, that e.g. “Money for Nothing” just doesn’t sound like you remember it, and felt it, no matter what equipment you feed in front?Anyway the question goes on bass “thumb” lower midtone, that smacks your chest to the beat, that 12” piston x-ing at 1000Hz going “THUMB”, like the purest feeling of firing up your big V8, praising the lord you haven’t become a modern man, with a lease on a electric toy car!Pops has become a modern man sadly, so no love for the old L65 no more, so I gladly and quickly made them get off his mind, and into my living room. -But why have they stopped “thumping” ??When I play tones 30-40-50..200hz they are all considerably lower than just a tad up the midrange, way before 1000hz the amplitude rises. They also sound fatiguingly sharp, so brilliance has to be turned down to 2, and by doing that I can hear the treble cuts out, if not wiggled back and forth some times, yes the pot is dirty. Woofer has been reconed in 2004 everything else is original. Amp is 300W Classé CA-2300 or 200W Cambridge Audio 851W both newly serviced. Speaker has been moved out 60cm, and smack up the wall with no difference. Polarity is checked. What is my NO thumbing issue here?What are my exact model?What are the cost no option filter refit for these?

  2. #2
    Senior Member BMWCCA's Avatar
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    Welcome!

    Immediate questions from your post (at least for me) would be:

    Re-coned? By whom? With what? Or did you really mean re-surround? Depending on your version, there are better alternatives for the woofer. I've always thought the 128H-1 was a superior woofer for bass and it is a direct fit. Different models all had different woofers, IIRC. The models were L65 Jubal, L65A Jubal, and L65B. Each had a different woofer. JBL suggests the 128H-1 as the best replacement for all the others. Only for the L65B do they consider the 128H-1 a similar acoustic performance to the original, and I kind of doubt that but others here will know much more than I do.

    Moving to a your place from your Dad's place. Your room acoustics are likely completely different. When I moved my 4345s from my old small and well-upholstered and carpeted living room to a more spacious one with less furniture per square-foot and much taller ceilings than where they has spent nearly ten-years, the dynamics changed . . . a whole lot! And they've got the same tweeter that you do.

    Barrier reinforcement? The L65 always sounded better if you got them a bit off the floor. While that helped with tweeter position, it will diminish the bass, just as moving them away from a side wall will. Back walls not so much since yours are front-ported and big enough I don't really think they need to be out further in the room.

    All the best for getting your kick back!
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Quote Originally Posted by BMWCCA View Post
    Welcome! Immediate questions from your post (at least for me) would be: Re-coned? By whom? With what? Or did you really mean re-surround? Depending on your version, there are better alternatives for the woofer. I've always thought the 128H-1 was a superior woofer for bass and it is a direct fit. Different models all had different woofers, IIRC. The models were L65 Jubal, L65A Jubal, and L65B. Each had a different woofer. JBL suggests the 128H-1 as the best replacement for all the others. Only for the L65B do they consider the 128H-1 a similar acoustic performance to the original, and I kind of doubt that but others here will know much more than I do.Moving to a your place from your Dad's place. Your room acoustics are likely completely different. When I moved my 4345s from my old small and well-upholstered and carpeted living room to a more spacious one with less furniture per square-foot and much taller ceilings than where they has spent nearly ten-years, the dynamics changed . . . a whole lot! And they've got the same tweeter that you do. Barrier reinforcement? The L65 always sounded better if you got them a bit off the floor. While that helped with tweeter position, it will diminish the bass, just as moving them away from a side wall will. Back walls not so much since yours are front-ported and big enough I don't really think they need to be out further in the room. All the best for getting your kick back!
    I mean re-surround of cause! By a certified JBL tech.I have of cause thought about room dimensions, but I'm not sure that's it entirely. Room is 3,5x7m and 4,5m tall - placed on the left side of the 7m wall, playing across the 3,5m. Listening position is then 3m away.I don't believe they are Jubals actually, but the picture upload doesnt seem to work. Ill post links instead. https://imgur.com/a/jQGKnNz I'll dismantle the woofer tomorrow and post pictures of exact model.

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    Senior Member BMWCCA's Avatar
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    Your serial number should indicate L65A, which should have the 122A 12-inch woofer. Re-surround looks well done.

    Do you have the same amps and the rest of the system from your Dad, too?

    Was polarity connection of the woofers done correctly when they were reinstalled after the surround replacement?

    Even the three different L65 schematics here can't seem to agree on what goes where and none list the polarity at the driver. Someone should be along soon enough to straighten out that JBL quirk in convention. Take a look at this one: https://manuals.harman.com/JBL/HOM/T...Jubal%20ts.pdf
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Quote Originally Posted by BMWCCA View Post
    Your serial number should indicate L65A, which should have the 122A 12-inch woofer. Re-surround looks well done.Do you have the same amps and the rest of the system from your Dad, too?Was polarity connection of the woofers done correctly when they were reinstalled after the surround replacement? Even the three different L65 schematics here can't seem to agree on what goes where and none list the polarity at the driver. Someone should be along soon enough to straighten out that JBL quirk in convention. Take a look at this one: https://manuals.harman.com/JBL/HOM/T...Jubal%20ts.pdf
    I've had the woofers out once. And I remember Alnico, a yellow sticker, if I'm not mistaken, the woofers are 126A - will confirm that tomorrow.NO! He had an old PIONEER SA-8500 at 60W RMS - that's why it makes even less sense with 5x the power, in real life being probably closer to 50x with that 40kg Classé!If polarity is wrong, it would suffer from a wild phase shift, and they don't.And does anyone have a clue, to why the site here, eats all my spacebar, and enter hits?? This looks like it's written by a crazy person haha

  6. #6
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by DonPeterD View Post
    I've had the woofers out once. And I remember Alnico, a yellow sticker, if I'm not mistaken, the woofers are 126A - will confirm that tomorrow.
    The original L65 had that woofer, according to the tech bulletin here: https://manuals.harman.com/JBL/HOM/T...Jubal%20ts.pdf

    The current issue with text formatting and photo upload is addressed here: https://www.audioheritage.org/vbulle...l=1#post442946

    Still no fix for the lack of emogis! ;(
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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