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DIY driver surround doping

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  • Brian Steele
    started a topic DIY driver surround doping

    DIY driver surround doping

    Just curious if any of you have tried doping the surrounds of any drivers and measured the results.

    I had to repair the detached/torn surround of a Bose AM7 subwoofer driver recently, and when I did some impedance measurements, it seems my "repair" eliminated the surround/cone resonance around 1kHz without significantly impacting the driver's other parameters. The "repair/doping" was done by basically using a popsicle stick to run a bead of siliconized caulk around the edge of the surround. The caulk dries clear and I wiped away the excess with a few tissues, so the result looks pretty neat (which means that anyone can do this and end up with a very neat result, given my fumble-fingers). The fix worked, but the bigger surprised was that the resonance at 1kHz completely disappeared (see impedance graph comparing the fixed driver to the other, unfixed one).

    I might end up trying this "fix" on one or two of my SF drivers, which show a nice big cone/surround resonance blip in their impedance curve...

  • Brian Steele
    replied
    Here's the close-miked FR of both drivers - in red is the FR of the undoped driver, in blue is the FR of the doped driver. The drivers are otherwise identical in build. Looks like the doping really does make a significant difference.

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  • kirk78h
    replied
    This may be a good application for Seal 'N Peel caulk. It has good adherence; but can also be removed with little to no damage.

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  • badman
    replied
    Nothing wrong with giving it a test. Worst case is driver damage, but I've been able to successfully modify almost every type of driver in one way or another, and I'm a fumblefinger like you. Expecting it to be as effective on the SF may be a little more of a stretch, the bose had the advantage of being very small and lightweight. Just measure a lot, and do it a little at a time, and you'll be good. IOW, start by doing 1/4 of the surround, in 4 strips around the cone and see what changes. Nothing, or a slight positive change? Add more and re-test. Negative change? Stop.

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  • geewhizbang
    replied
    Speakerlab used to spray some black rubbery paint on inexpensive Phillips drivers, called it "Polylam" and despite the hype it probably did make them sound a bit better.

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