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Thread: Sloped front JBL?

  1. #1
    Member jbl-ahhh's Avatar
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    Sloped front JBL?

    Does anyone know of a JBL speaker other than the L3 (see photo) that has a flat front on the bottom half and drivers on a slanted front on the top half? The owner of the ballet studio where my daughter dances uses a pair of 13 or so year old JBLs shaped like that but isn't sure what model they are. She says one of them "has slowly started making a bad sound" so I told her I would try to fix them.

    Maybe just a shot surround causing the voice coil to rub. Hopefully she hasn't been playing them since the noise started. What damage is common if a driver is played too much with a decayed surround? Does the voice coil crack or the spider get torn?
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    Senior Member BMWCCA's Avatar
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    Could be any of the entire L-series from L1 to L7. You might want to ask how many drivers are in each cabinet, or just have her look on the back "where the wires connect" and read the model number. All of those L-series use rubber surrounds so they're likely not deteriorated but they could have come unglued and that could cause a "flapping" sound.

    So, how do you know it's not an L3?? What information did you forget to share?

    ". . . 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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    Member jbl-ahhh's Avatar
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    My original post wasn't very clear. Sorry 'bout that. It definitely could be an L3, but I won't know for sure until Tuesday when I pick it up because she doesn't know much about it and can't get it down by herself from its high perch. My daughter says the bottom part of the cabinet is not slanted and has no drivers, so it's not an L1 or L5 or L7. If JBL made other slanted front speakers around the mid 1990s, then it might not be an L3.

    I offered to try to fix it and was hoping to get information on any other possible models so I'll be a step ahead come Tuesday. In case it is an L3, knowing about the rubber surrounds helps. Thanks. If the rubber surround is coming unglued from the basket, that would be an easy fix.

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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by jbl-ahhh View Post
    If the rubber surround is coming unglued from the basket, that would be an easy fix.
    You might want to do a search here for "butyl" or "rubber" with "surround" and see what the collective wisdom over the years says about it. I hesitated to buy any of the L-models after reading about separation here. That being said, many have offered different solutions to the type of glue to best affect a repair. Myself, I've never had any of my four pair come apart. Personally I'd still try Aleene's Tacky Glue first. Available at WalMart and Michael's, and many others.

    Was there more to the description than just the "bad sound"?

    Good luck. And remember, we love pictures!
    ". . . 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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    Member jbl-ahhh's Avatar
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    Yep, Aleene's glue worked great reattaching portions of the rubber surrounds on my vintage Infinity woofers. (Can I use the "I" word here? ).

    No additional problem description from the owner. I'll post Tuesday or Wednesday about what I find and include pics. I'm hoping for the best. After all, I don't want my daughter dancing to less that fully functioning JBLs!

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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by jbl-ahhh View Post
    Yep, Aleene's glue worked great reattaching portions of the rubber surrounds on my vintage Infinity woofers. (Can I use the "I" word here? ).
    Actually Infinity is part of the Harman family these days so you're okay there. I used Rick Cobb's glue on a set of surrounds for some Infinity RS-4001 speakers with the Injection-Molded-Graphite cones and it worked great...just like Aleene's.
    ". . . 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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    Senior Member Beowulf57's Avatar
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    Given the vague description of the sound problem...do try cleaning and re-tightening all the connections. It might be a simple contact oxidation problem. Also don't neglect to check any signal cables and switches in that problem channel.

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    Member jbl-ahhh's Avatar
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    It is an L3. A bit of a hairy job getting it down off the high shelf with just me and a ladder.

    The pics show the woofer's rubber surround has split right where it joins the cone, so the surround has to be replaced. It is glued to the underside of the cone, making removal more tedious, but a quick scraping test showed it will probably come off okay.

    Does anyone know who might have replacement surrounds for L3's? Rick Cobb does not. If anyone has done these surrounds, are there any gotchyas?
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    Senior Member BMWCCA's Avatar
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    Bummer!

    Orange County shows an edge kit but it looks to be foam, which is actually what the remnants of yours looks like on the back of the cone. Working on the back of the cone isn't that hard and is common on JBLs, though it's more accessible on larger speakers. I'm more interested in knowing where the surround gets glued to the frame; is there a bezel of some kind that is removable? I'm not willing to disassemble my L7s or L5s right now to find out.

    OC shows the kit here at $30 a pair: http://www.speakerrepair.com/mm5/mer...Category_Code=
    though it doesn't look particularly unique for the 708G-1. I'm sure Cobb could supply the same kit but he probably knows it's not the same as the rubber JBL used, if that is what it is. Plus OC's linked repair price list doesn't even show a 708G-1. They do show a repaired 708G-1 here but list it under close-out: http://speakercloseouts.com/repairpi...08g1-pics.html

    You could take a chance on a pair of 708G-1s right now on Ebay for a BIN of $100. But add another $100 to that and you'd probably be able to find a pair of L5s if not L7s. It's a dilemma, for sure.

    There is a pair of L3s on Craig's List in Augusta, Maine, that have gone nowhere at $225 and are now in a combined ad for a bunch of stuff listed as "want gone asap". Might not be that far from you, or a good reason to go to Maine?

    The last single 708G-1 I saw on Epay only brought about $20. You could wait for another, but you might also want to check your friend's other L3 for any similar damage.

    Good luck.
    ". . . 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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    Senior Member rdgrimes's Avatar
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    If one has done this, you can bet money that the other is not far behind. Do them both. Shouldn't be hard to re-foam them at all.

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    Member jbl-ahhh's Avatar
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    Yeah, I'm planning on doing the other L3 right after this one. One at a time so the studio still has music.

    I re-edged my 4411's which are glued on the back of the cone. It went fine, but those 12-inchers have a lot more finger room on their backside than the 708G-1 does!

    The 708G-1 surround has just a 1/8" outer lip which glues to the frame. And there's no gasket or anything on top of it, no bezel to remove. The inner lip attaching to the cone is 1/4", maybe 5/16." Since much of the glue is still intact, I'm trying heating the surround with a hair dryer to get it to come off the cone cleanly and safely.

    I'm thinking that buying used would only postpone the inevitable unless the used woofers have been re-edged. Thanks for the link to OC. I'll check if they have a butyl version.

    Any thoughts on if foam would be alright? These L3's are used in a dance studio and always will be, so maybe foam surrounds wouldn't be noticed sonically? Or am I just talking myself into something?

  12. #12
    Senior Member rdgrimes's Avatar
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    The 8" drivers (117H) I have re-foamed were the easiest of all. Because of the fit of the surround they practically centered themselves. Much easier than the larger models IMHO. You'll be hard pressed to hear any difference between butyl and foam once they get broke in.

  13. #13
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    Quote Originally Posted by rdgrimes View Post
    You'll be hard pressed to hear any difference between butyl and foam once they get broke in.
    And from looking at those photos of the remainder of the surround on the back of that 708G-1, I'm not sure that what we've assumed were butyl surrounds on the 708G are really that at all and not just normal poly-foam with a smoother finish. :dont-know

    It does look like the surround on the smaller 704G-1 in the L7 is actually some composite with reinforcement built into the surround. The 708 looks more simple, for some reason.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  14. #14
    Member jbl-ahhh's Avatar
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    I agree, it is a wierd surround material. The front side sure looks and feels like butyl, but the backside looks and feels like foam (see pics). Given the short lifespan, I don't see how it could be butyl.

    It probably doesn't matter since I think it will have to be foam surrounds by default because I'm striking out trying to find butyl. And Orange County Speaker said their foam surround isn't actually the right size for the 708G -- I would have to trim a bunch off from theirs. I sent an e-mail to the service folks at the JBL website and got a list of places to try next. Is this the fun part?
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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by jbl-ahhh View Post
    Is this the fun part?
    I think you are a true pioneer in this endeavor.

    What were JBL's suggestions? Did they tell you what material they called it? The catalog is far from clear.
    ". . . 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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