Question about KLH ASW10-120 Subwoofer

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Hum no audio output - KLH ASW10-120 Subwoofer

Posted by smiller6911 on


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Rob C

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There are a lot of folks who've had power supply issues with this sub. Typically, the large resistors fail, which takes out the capacitors.

If you know how to read schematics and replace parts, then these might be helpful to you:

Here are the two pages of schematics from KLH. I wrote to their tech department and explicitly asked for permission to share them here.

Here's the lower board, which has the power supply:
KLH ASW 10-120 subwoofer schematic - lower board

Here's the upper board:

KLH ASW 10-120 subwoofer schematic - upper board

Posted on Dec 22, 2009

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  • Brian Oliver May 09, 2012

    I just had this problem occur on my ASW 10-120 a few days ago, and I guessed it was one of the power supply caps (6800 uF). I replaced both caps and a couple of other nearby ones and the loud hum has gone away, but it still has an offset on the speaker output (~1 volt). Unfortunately, the schematic you posted doesn't appear to be the same as my unit (S/N 23785). The most obvious difference is that my power supply has both +16V and -16V for the preamp which are regulated by individual zener diodes, but these zeners are not connected to the base of any transistors. Your schematic shows only a +16V (or perhaps +18V - it's hard to read) from the power supply controlled by one zener/transistor combination. I got this used from a fellow down the street in about 2000.

  • jcqcomm Oct 23, 2016

    |Your provided link for the upper board is still good, but the document for the lower board is no longer there. Is it possible to re-post it?

    Thank you

  • Rob C Oct 29, 2016

    Looks like scribd killed off the old docs. Here they are in Drive: Lower Board: and upper board:



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