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Thread: jbl 4311 - replacing mid and tweeter

  1. #1
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    jbl 4311 - replacing mid and tweeter

    hello everyone
    i have a pair of 4311. In one of them the tweeter and mid need to be raplaced. The cone of the tweeter is pressed in and cracked, and the mid seems burnt (I measured it with a multimeter).

    I tried to remove the tweeter, but it's glued on and doesn't seem easy to become unstuck. I tried removing the woofer to gain access to the inside and maybe push it out, but the woofer is also glued. It seems hard to remove any of them without damaging the wood.

    Any help on how to proceed appreciated

  2. #2
    Dang. Amateur speakerdave's Avatar
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    I doubt they are glued; more likely they are just gasket-stuck. I would suggest you try gently working a thin-bladed wall knife (or putty knife) under the edge and gradually loosen it all around. Put some stout paper under the wall knife to keep from marring the surface of the baffle. I would cut a circle out of a piece of card stock to fit around the driver and tape it in place. The main thing is patience and working slowly.

    I'm not sure which tweeter that is--the LE25, I think. They can be found used at reasonable prices.

    The midrange should be the 2105. That also shows up on ebay for fairly reasonable prices. They are no longer serviceable at JBL, so be sure you get one that is in good working condition.

    David
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  3. #3
    Senior Member mbd7's Avatar
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    One of my favorite tools

    For speakers and everything thing else.

    Dave, thanks for the chuckle!

    mbd

  4. #4
    Dang. Amateur speakerdave's Avatar
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    Quote Originally Posted by mbd7 View Post
    For speakers and everything thing else.

    Dave, thanks for the chuckle!

    mbd
    Actually, I didn't mean anything by it. It was just that since the question came from someone in Greece, I didn't know if the word "knife" would have all the same meanings to him.

    David

  5. #5
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    thanks for replying,

    speakerdave, the tweeters are actually glued on. The glue is visible between the tweeter metal casing and the wooden cabinet.
    I tried removing them with a knife but the glue was too hard (I didn't force it much). I'll give it a go again and see...

    btw I just spoke with a friend of mine in the UK who has the same model and his tweeters are also glued...

  6. #6
    Dang. Amateur speakerdave's Avatar
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    You might be trying to pry the tweeter apart. There may be a plastic layer, a metal layer (the body of the tweeter), and a thick paper/cardboard gasket under that. The glue you're seeing may be holding the plastic to the metal body of the tweeter. Don't pry hard on the plastic layer; you may snap the edge. I'm looking at an LE26, assuming the LE25 is similar. You may need to work the knife in at a steep angle to get under the metal layer if it is recessed into the baffle board. That appears to be the case with my son's 4311. If you can't get it out without digging up the baffle board, you may need to pull the woofer and rapp the tweeter from behind while you're prying on it. You probably will be replacing that tweeter rather than reconing it, so it's not critical, but still, it would be nice to get it out without wrecking something.

    The cast metal mounting flange of the midrange is mounted to the surface of the baffle board. Are you seeing glue there? It should not be glued. The drivers are held in place with screws. The factory may have used some sealant like duct seal to prevent the enclosure from leaking and losing tune (AR did this). I don't think JBL did this, but if so it will hold the driver some, but not like glue. It will let go. I think, however, you will find that in both cases there are paper/cardboard gaskets which, under pressure all these years, have stuck to the finish and the driver. They will let go with reasonable outward pressure

    David

  7. #7
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    david, thanks a lot for your help.

    here are some pix of the speaker:
    http://www.audioheritage.org/images/.../l100-431x.jpg
    http://blog1.musicfield.jp/du_ao1/archives/4311B.jpg

    these speakers are of great sentimental value to my father, so i did not force them at all.

    it seems the tweeter is held by those 4 screws at the corners. the glue is under the metal square part of the chassis of the tweeter (which is screwed on the cabinet). It seems that no other layers exist between the metal and the cabinet, other than the glue.

    the mid-range had no glue or anything else, i could easily remove it when i removed the screws.

    I haven't made another attempt to remove it, as i had no spare time the last days, i'll try using a spatula (or whatever it's called) as you suggested in your first post.

    please tell me if i'm missing something

    stefanos

  8. #8
    Dang. Amateur speakerdave's Avatar
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    OK. There may be some sealant under the tweeter mounting flange. There is a subenclosure behind the midrange to shield its cone from the back pressure of the woofer in the cabinet. The tweeter is enclosed in itself and so doesn't need that and backs directly into the enclosure space I believe. JBL may have found it necessary to mount it with duct seal or something similar to get rid of air leaks around it. They would know these tweeters may need to be demounted if blown, so they would not glue them. If there is sealant it will hold unto the tweeter, but not like glue. It should let go with reasonable upward pressure.

    David

  9. #9
    Senior Member grumpy's Avatar
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    To add to speakerdave's advice:

    I've removed an LE25 from a 4311WX-A . It -can- be difficult to
    remove them without damaging the front of the cabinet (having bits of
    cabinet stay stuck with the tweeter). Cutting a scribe line along the edge
    of the tweeter helped. There was indeed a paper gasket underneath, but
    there was also a "seal" that didn't want to give up easily... whether it was
    intentional or paint that was wet when the assembly went together,
    it was mostly just the edge that was stuck. Just be careful and take your
    time. -grumpy

  10. #10
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    success...
    ok i managed to remove it. as speakerdave suggested what appeared to be glue was in fact sealant (tiny amount around the edge). There was a layer of paper or something between the tweeter chassis and the enclosure which was stuck to the finish (and that was keeping the tweeter there). I followed grumpy's advice and cut the sealant around. No damage was done on the wooden front, just to that paper layer, which partly remains stuck on the front, but seems easy to remove...

    I tested it with other drivers in place of the tweeter and mid, and the crossover seems ok. Since these speakers are so old, should I check/replace any parts of the crossover?

    thanks to all for the help,
    next step, finding replacement parts....

  11. #11
    Dang. Amateur speakerdave's Avatar
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    Cool. Glad it worked out for you. Both the LE25 and the 2105 have shown upon ebay since this thread started. If they're gone, it'll happen again.

    David

  12. #12
    Senior Member brutal's Avatar
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    Quote Originally Posted by speakerdave View Post
    You might be trying to pry the tweeter apart. There may be a plastic layer, a metal layer (the body of the tweeter), and a thick paper/cardboard gasket under that. The glue you're seeing may be holding the plastic to the metal body of the tweeter. Don't pry hard on the plastic layer; you may snap the edge. I'm looking at an LE26, assuming the LE25 is similar. You may need to work the knife in at a steep angle to get under the metal layer if it is recessed into the baffle board. That appears to be the case with my son's 4311. If you can't get it out without digging up the baffle board, you may need to pull the woofer and rapp the tweeter from behind while you're prying on it. You probably will be replacing that tweeter rather than reconing it, so it's not critical, but still, it would be nice to get it out without wrecking something.

    The cast metal mounting flange of the midrange is mounted to the surface of the baffle board. Are you seeing glue there? It should not be glued. The drivers are held in place with screws. The factory may have used some sealant like duct seal to prevent the enclosure from leaking and losing tune (AR did this). I don't think JBL did this, but if so it will hold the driver some, but not like glue. It will let go. I think, however, you will find that in both cases there are paper/cardboard gaskets which, under pressure all these years, have stuck to the finish and the driver. They will let go with reasonable outward pressure

    David
    Sometimes a sharp smack on a horizontal edge using a piece of wood and a plastic or lightweight hammer works to pop those sticky buggers off.


  13. #13
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    Question le 25 and le5-2

    hi,
    i,m new to the forum and need help. i bought some 4311s and both mids and both tweeters dont work. my question is how can i tell if the problem is the speakers or the crossovers oor some other components? thanks for any help

  14. #14
    Senior Member SMKSoundPro's Avatar
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    Remove the non-working units and test for continuity across the two terminals. It will read 4-12 ohms if good, and open if bad.

    Also, sweep the mid and high controls back and forht to "scrub" the contacts in the l-pads.

    Dump the 4311's on the net for firewood, and get some big L200b's to rock the house!

    Scott.
    One step above: "Two Tin Cans and a String!"
    Longtime Alaskan Low-Fi Guy - E=MC▓ ▒3db

  15. #15
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    I've also got a pair of 4311s which I like a lot. They seem to need some attention, and I am doing my best but I am a bit lost with an issue.
    I replaced already a blown tweeter (difficult to take out because of the gasket and sealant). Now I seem to have a blown midrange too, but I am not positive it was blown when the speakers first came home.
    Would a bad crossover kill the tweeter and / or the midange?
    The thing is I would like to check both crossovers anyway, but I don't know how to get to them. Once I saw one of those crossovers and they have two holes to screw them somewhere, but there are no screws to be seen on the front face of the box, so I don't know how they are serviced -if they ever are- I figured new capacitors may improve the performance of the speakers, as old paper capacitors tend to go bad and leak with the years, but again I am not really sure in this case. Any suggestion very much appreciated, and happy New Year!

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