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Speaker repair?

Anyone know anything about speaker repair?

I've got a pair of speaker cabinets that my parents gave me when they invested in a modern 7.1 speaker system. Recently the woofer in one of the cabinets stopped producing sound. After disassembling the cabinet, I was able to determine that the woofer has a short (0 ohms).

Googling around for parts, I've discovered that it's a valuable vintage set (Sansui SP-1700s), which means that:

  • It may actually be worth the trouble of repairing, and
  • Spare parts are not available
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6 comments to Speaker repair?

  • You may want to cross-post this to since I know Prefect and Mute and some others do speaker repair.

  • Okay, let’s see.

    Here’s an FAQ with some basic info:

    http://www.jblpro.com/catalog/support/faqgeneralaudio.aspx

    If you’re seeing 0 ohms through there, my guess is that the voice coil is burnt, like if you sent too much power or a big DC spike through it. You may not be able to see this, since it’s likely that the coil is actually inside the magnet on the back of the driver. (Awesome speaker dude jargon: the “driver” is the actual speakery piece in there– the woofer is one driver, the tweeter is another, and so on. So you may want to do web searches for replacement drivers rather than replacement speakers.)

    I’m hoping that if you’ve taken it apart that far, you’ve already checked the obvious stuff, like wires touching or something, right? If not, check that first. Once you have, and if it’s not that, onward.

    One easy way to tell if it’s a coil problem (at least an obvious and nasty problem) is to push very very gently in on the middle of the speaker (not off-center, but if the dome in the middle is made of something soft, don’t push it directly or you’ll dent it, and that’s potentially bad too). If it moves in and out smoothly (and if it’s a woofer, it may have a pretty good amount of freedom– 1/4″ or more, but be VERY careful testing this since if you push it in too far you can crush the coil yourself or rip the ) that’s relatively good. If you feel scraping or if there’s resistance, the coils are shot and either you get to do some very touchy and delicate rewinding, or you might as well give up and replace the driver.

    Most of the expense of a loudspeaker is the design and materials for the cabinet and the crossover design and so on. The drivers themselves are relatively inexpensive. I repaired my Model 12’s by finding midrange drivers the same size as the originals and with a similar frequency response. That may be easiest, since rewinding speaker coils is very fiddly and probably not worth the trouble.

    Looking at the material here:
    http://www.classicsansui.net/images/Literature/Speakers/SP1700.jpg
    http://www.classicsansui.net/images/Literature/Speakers/SP1700%202.jpg

    …you can at least find the size and frequency response. The crossover frequency is at 700Hz, so you would look at the graph there and try to find a driver of a similar size with similar response up to the 700Hz line. That shouldn’t be too tough, really. You’d probably want to replace it on both speakers, too, so they stay symmetrical…

    Those are some cool-looking speakers.

    • I’ve already searched for a replacement driver (Sansui W-110) and found absolutely none. As near as I can tell, this is the only model that used that particular driver, and it seems to be one of the more obscure Sansui models. :-(

      I removed the driver from the housing and disconnected it, and there’s no touching wires visible. In fact, visually everything looks in great shape. No noticeable wear on any part of the driver, just a bit dusty. The dome bit moves in and out smoothly.

      All of which makes me feel quite awful that it blew under my care. My best guess is that I may have unplugged and touched the input to the amp while the amp was turned out and the random noise sent a big spike. I tend to have the amp’s volume up pretty high because the Apple Airport outputs a small signal. Blah.

      How would I go about looking for a driver with similar response?

      If I took it in to a speaker repair shop, is there any chance they’d be able to repair the driver itself, or is that basically hopeless? (a shame since the driver looks great from the outside)

      Thanks!

      • They might be able to repair it, but it would very likely be super expensive. See ‘s reply elsewhere for a little more info on that.

        When I talked about replacing it, I meant with a new driver with similar specs, since an exact replacement may not be possible (or may mean stalking ebay for parts).

        • When I talked about replacing it, I meant with a new driver with similar specs, since an exact replacement may not be possible (or may mean stalking ebay for parts).

          Right, right–but how do I go about doing that? Is there a website where I can browse drivers along with links to their frequency response graphs?

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