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Thread: Dented panel - simple repair - with care, please!

  1. #1
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    Jul 2012
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    Portland, United Kingdom
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    Default Dented panel - simple repair - with care, please!

    I re-panelled my Quest Zs in 2012 with help from Absolute Sounds and ML - an expensive but worthwhile business. A few months ago, one panel began to make an occasional popping sound. This came and went, and eventually, when present, the pops ran together into an audible hiss. I asked the ever-helpful Dana Brown in ML Service for help, and his reply led suggested low-level breakdown in insulation.

    Vacuuming, swapping crossover units, and checking insulation on cables led nowhere. It was only when I removed the panel FOLLOWING ALL NORMAL SAFETY precautions to ensure that the panels were fully discharged that I was able to locate the problem. With the panel de-energised, disconnected and removed from the rest of the speaker, I laid the panel front side up on a table top under a strong light, and a small indentation in the front of panel revealed itself exactly where the interference had seemed strongest. The dent lay more or less midway between two of the horizontal insulation strips. With care and a bit of experimentation, I was able to thread a piece of strong sewing thread (the sort used for canvas or leather) between adjacent perforations. Taking care to ensure that I did not pull out any glue joints on any spacers, I was able to apply tension - eventually lifting the entire weight of the panel on the loop of thread. Three or so repeats with the thread in different positions were enough to 'pull' the dent out completely, and I was very relieved to find that the interference had been eradicated once the speaker was put back together.

    If you have a similar problem, please consider my solution, but only after you have ensured that:
    1. you know how to safely discharge and remove the panels,
    2. you use thread which will pass through the perforations without damage to the diaphragm and take the weight required, and
    3. that you check that the glue joints will not be affected by the tension you apply.
    For the latter point, I would advise that you proceed slowly and carefully. Dana has looked at my method and encouraged me to share it. Nevertheless, any risk or damage that results is your fault, not mine or Dana's!

  2. #2
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    Jul 2012
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    On reviewing my post, I think it important to credit my wife with the idea of the thread - I'd tried cable ties, tweezers (!), needle-nosed pliers (!!) and plastic-coated wire wraps, all of which were too rigid. When applying tension, using your other hand to steady the area around the dent may help.

  3. #3
    Junior Member
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    Jun 2015
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    Hong Kong
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    Quote Originally Posted by jandswalker View Post
    On reviewing my post, I think it important to credit my wife with the idea of the thread - I'd tried cable ties, tweezers (!), needle-nosed pliers (!!) and plastic-coated wire wraps, all of which were too rigid. When applying tension, using your other hand to steady the area around the dent may help.
    Hi Jandswalker, thanks for the tip. I followed your method on a Matinee centre channel speaker I recently picked up which had a dented panel. I used the nylon rope-like tape used to tie boxes. Its soft but incredibly strong so won't damage the insulation coating on the stator. Instead of pressing down with my hand, I put a roll of tape on its side and pulled through the cardboard ring while exerting downward pressure on it. Worked beautifully. Thanks a lot!

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