[net.audio] Car speaker problem

jwp@uwmacc.UUCP (Jeffrey W Percival) (01/07/86)

I know zero about speakers, so this problem might seem pretty
trivial to a lot of you...

One of the two speakers in my car is making a "fuzzy" noise that
correlates with low notes in the music.  The problem just sort
of started up.  I don't use excessive volume in the car, and only
I drive it, so I don't think the speaker has been exposed to
damaging signal strengths.  Do speakers randomly go bad like that?

I bought it 2.5 years ago, and it is a fairly good one (I forget
the brand and type, but I can find out if anyone is interested).
I took it out of its bracket in the trunk, and I found that if I
touched the paper lightly, the noise went away (along with the
bass response).  There were no visible defects.  Any thoughts?

	Jeff


-- 
	Jeff Percival ...!uwvax!uwmacc!jwp

saf@bonnie.UUCP (Steve Falco) (01/09/86)

> One of the two speakers in my car is making a "fuzzy" noise that
> correlates with low notes in the music.  Do speakers randomly go bad
> like that?

Yep.  The car environment is pretty rough with very high and very low
temps. plus humidity.  It is entirely possible that the cone has warped
slightly causing the voice coil to rub - this makes the fuzzy noise.
It is also possible to warp the basket of the speaker by mounting it on
a less than flat surface and/or overtightning the screws.

If switching the speaker leads (switch left & right) doesn't cause the
fuzz to move to the other side of the car, you can be sure it's in the
speaker.  If the problem moves, then it is in the radio/tape unit.

If the speakers have a long warantee, you might get a free replacement.
I know that most home systems have at least a 5 year warantee but I
don't know what car speakers typically have.  Good Luck.

	Steve Falco  AT&T Bell Laboratories

fish@ihlpm.UUCP (Bob Fishell) (01/15/86)

> > One of the two speakers in my car is making a "fuzzy" noise that
> > correlates with low notes in the music.  Do speakers randomly go bad
> > like that?
> 
> Yep.  The car environment is pretty rough with very high and very low
> temps. plus humidity.  It is entirely possible that the cone has warped
> slightly causing the voice coil to rub - this makes the fuzzy noise.
> It is also possible to warp the basket of the speaker by mounting it on
> a less than flat surface and/or overtightning the screws.

All this is true, but I'd like to add that there is a basic problem with
the construction of many auto speakers that can produce the effects
described.  Most Auto speakers are the "coaxial" variety, which place the
tweeter and possibly, a midrange driver, in front of the woofer.  These
are usually attached to the speaker terminals by gauze wire that is
attached to the surface of the woofer.  As the auto speakers are usually
long-throw types, this creates considerable flexing of the attaching
wires.  Metal fatigue eventually sets in, the gauze deteriorates, and
you get a variable resistance that's modulated by the bass driver.  I've
experienced this with two sets of auto speakers.

In each case, the prescription is to snip off the gauze connections
and wire the tweeter/midrange/crossover assembly to the terminals via
a bypass wire that is routed around the woofer cone.  I used 20-gauge
stranded zipcord for the repairs.  I also drilled holes in the speaker
housing to route the wires through, so I could get the grilles back on.
This took care of the problems, and it's held up for over two years now.
-- 
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				Bob Fishell
				ihnp4!ihlpm!fish