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Speaker foam repair on 15" woofers

Discussion in 'Electronic Repair' started by [email protected], Nov 21, 2013.

  1. Guest

    Hello all!

    I have a pair of Optimus 1050 (Radio Shack) 3-way home stereo speakers
    that are about 20 years old. The foam ring that goes between the outer
    edge of the cone and the steel frame of each 15" woofer is starting to
    split/tear. The speakers still work, but I know it's not a good idea to
    run them once the split goes all the way around. Looking around the
    net, several places sell repair kits for this.

    I have never done it before, but it seems fairly straightforward, except
    for one thing: there appears to be a difference of opinion on whether
    you need to remove the dust cap and stick shims in between the voice
    coil former and the pole piece to center the cone or not. Some places
    say you do, while others seem to prefer moving the cone by hand and
    centering it before the glue on the new foam dries completely. Which
    way does the group prefer?

    These are not audio pile speakers. I think I paid $100-$120 each (on
    sale) new, and I think I can get complete replacement woofers for $40 or
    $50. The main idea here is to get working speakers for less money than
    replacing the woofer or the whole speaker. The kits vary in cost and
    also in what they include. Is there any US supplier that stands out?


    Matt Roberds
  2. Guest

    I vote for shimming, it really can't hurt, and as long as you don't get dirt into the open gap, yhou should be fine.
  3. Guest

    I did 6 Advent woofers. The first kit included shims to keep the voice coilcentered and had new dustcaps. I did what they said and it works fine. Thelater kits did not include shims and even though I had them, I did not useshims or replace the dustcaps. Those drivers also work fine.

    It isn't difficult or even tedious but you do have to wait for the glues tocure.

    I don't vote for shims as it requires careful removal of the dustcap to NOTdamage the voice coil leads. Never disassemble more than necessary.

  4. Bob F

    Bob F Guest

    I did not find shimming necessary. If you carefully push the dome in and out and
    there is no rubbing sound, they tend to work. You can also glue the foam to the
    cone, then hold the outer edge in position and try them out. If you can sweep
    though the audio range without distortion, that's the position you want to glue
    them in. There are audio signal generator programs available to generate audio
    tones of varying frequency. Feed that into your amp to test.

    FWIW, I've done 4 pairs of speakers of various sorts. I bought a kit of foam
    surrounds fairly cheaply that contained several of various sizes. I still have
    most of them left. That kit, of course, only went to 12"
  5. N_Cook

    N_Cook Guest

    If you go the shimming route. I mark across the dome to cone join as a
    reference , then cut a neat ring with a narrow tip scalpel. Shims 3x 2mm
    wide strips of credit card. Reglue the cone with thin hotmelt string and
    felt-tip/painted black glue line, easier if you ever have to remove
    again. Unless the cones are on view, no cloth cover, then a more
    cosmetic glue line required
  6. amdx

    amdx Guest

    As a curiosity, would applying a small voltage across the voice coil
    keep the cone centered without causing other problems?
    (small--1, 2, maybe 3 volts)

  7. amdx

    amdx Guest

    I was originally thinking a DC voltage, and then had a second thought,
    How about a 20khz low voltage signal, wouldn't hear it, but it may
    keep things centered, or even force the fresh glue joint to move and
    release any tension you/it may have caused installing the foam ring.

  8. I have a pair of Optimus 1050 (Radio Shack) 3-way speakers

    Just like it's not a good idea to use your car when the tire pops off the rim.
  9. Guest

    Thanks for the responses! It will be a week or two before I get to
    fixing these speakers; I'll post back with results.

    Matt Roberds
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