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Thread: Restoring 4320's / LE85 diaphram issue

  1. #1
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    Restoring 4320's / LE85 diaphram issue

    Hello all,

    I am in the slow process of restoring a pair of 4320's that belonged to my parents for many years, and have hit a wall with one of the LE85's. Once I got the woofers up to snuff, I hooked the pair of speakers to test, and was disappointed to find that one of the horns was buzzing. I removed it and took it Freeman-Tuell in Dallas to get it serviced. The tech took it directly to his bench and hooked it to a signal generator (sweep generator?) and confirmed what I thought, which was that it needed a new diaphragm. He said it would take a couple of weeks, and would cost about $200. That was months ago. The first report was that the replacement diaphragm didn't fit as it should have, and that JBL was looking into a supply problem. Next report was that the new diaphragms were designed for horns made after XXXX year, or XXXXX serial number, and that the work-around was to have JBL machine the groove in the magnet to allow the wider coil of the diaphragm. Next update was that JBL is no longer offering the machining service for the magnets, and that they (Freeman-Tuell) were looking into alternatives. I've had to call them for each update, and I haven't bothered in a couple of months. I assume my horn is sitting on a shelf collecting dust. I have considered just buying a horn on e-bay, but would prefer to buy a matched, close serial #'d pair. That's an expensive (and slightly risky) alternative. I have also considered gambling a much smaller sum of money one of the non-OEM diaphragms. I have also considered just giving up on the project altogether and selling the parts.

    Is this a familiar problem with LE85's? Is there anyone else out there who has experienced the same thing and can provide some information about how to resolve this issue? Any info would be greatly appreciated. Thanks in advance.

    Regards,
    David

  2. #2
    Senior Member
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    Don't part them out over a blown diaphragm. If nothing else get the driver back, buy a pair of 1.75" Radians, get the speakers back running. A couple of threads:

    http://www.audioheritage.org/vbulletin/showthread.php?29722-Diaphragm-options-for-2420-LE85

    http://www.audioheritage.org/vbullet...9-175-diaphram

    I wouldn't machine the LE85. Maybe get some more recent 1" compression drivers to use until you can land a NOS pair of D16R2420 or whatever the tangential surround aluminums were.

    I wouldn't buy another pair of LE85s off eBay, chances are they'll need work, too.

  3. #3
    RE: Member when? subwoof's Avatar
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    guide holes

    chances are that "tech" is younger than the speakers and doesn't know any of the old tricks.

    75% of ALL the older alnico drivers that use the guide pins have to have the matching holes on the dia drilled out slightly to allow room to align.

    it's been over 30 YEARS since any alnicos were sold so unlikely any "spotcheck" by the production lines is done anymore - no matter the country.

    this is SOP whenever I refurb old drivers and it is very rare that one will not work BUT it has happened...

    ask that tech if he know this. if not, look elsewhere

    sub

  4. #4
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    I never thought about the pins, I was thinking about some of the posts mentioning excess varnish on the voice coils of the new production ring radiator 'phragms. But your post makes more sense!

    I hope the guy doesn't part his speakers out over it

  5. #5
    Senior Member
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    I use the Radian diaphragms in my 2420. I am happy with them. If the boxes are really nice you could try to get second hand JBL aluminium diaphragms in order to increase market value.

  6. #6
    Senior Member
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    If you replace the diaphragm in one driver with anything other than an original design/style, you will need to do both so they match. If your other diaphragm is still good, and has a tangential surround, I would be interested in purchasing it.

    Thanks

  7. #7
    Senior Member remusr's Avatar
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    My recommend....Buy a couple of the cheap aftermarket diaphragms for $40-50ea or $80 for Radian and get your LE85 back from that uninterested shop and hope it is undamaged further. Don't use them again. Put one new dia in it and see if you are aware of differing sound. Might be a bit brighter, maybe not noticeable. If so, carefully remove the other oem dia and put in a new one so both have same dia's. See if you are ok. If not, watch for & buy a new JBL dia - expect $150+, or a replacement LE85 with oem dia.
    Here's one that looks real nice, red wax so may be oem, $185 starting bid c/w horn. http://www.ebay.com/itm/Vintage-JBL-...item1c4bfa8280
    But I'd try a new cheapie dia first.

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