From: "Simon Byrnand"
Subject: Re: Woofer repair
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Date: Fri, 22 Nov 2002 13:47:49 +1300
NNTP-Posting-Date: Fri, 22 Nov 2002 13:48:21 NZDT
"EBG" wrote in message
> The woofer is not connected to a crossover.
> It's in free air and it isn't the charcateristic resonance peak I'm
> I'm asking ....what construction detail would lend itself to this kind of
> The woofer is obviously defective.
Depends what the "distortion" sounds like, but as Greg pointed out, the
tinsel leads from the terminals to the cone could have a break, I've had
this happen on a 12" woofer before, and at certain low frequencies it
sounded a bit distorted, almost as if something was rubbing, but it was the
lead going momentarily open circuit with the movement. That kind of problem
can be difficult to find, because the leads usually look fine and measure
fine when the speaker is not moving.
If you carefully grasp sections of the lead while the speaker is vibrating
and the distortion suddenly stops, this is probably your problem.
The other most likely reason is a damaged or misaligned voice coil, making
the voice coil former rub on the magnet, perhaps caused by overheating or
If the problem is misalignment of the voice coil then if you set the volume
to the point where it just starts to distort, then push lightly near the
outer edge of the cone and listen to the change, you'll find that on one
side it stops the distortion and on the opposite side it makes it worse.
If its bad all the time then its possible its not misalignment, but rather
that the voice coil is damaged from overheating, perhaps the glue has
bubbled up from overheating and is touching the magnet all the time.
In either case repair can be extremely difficult unless you have previous
experience making those kind of repairs....