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From: fish@ihlpm.UUCP (Bob Fishell)
Newsgroups: net.audio,net.auto.tech
Subject: Re: Car speaker problem
Message-ID: <663@ihlpm.UUCP>
Date: Tue, 14-Jan-86 18:00:17 EST
Article-I.D.: ihlpm.663
Posted: Tue Jan 14 18:00:17 1986
Date-Received: Fri, 17-Jan-86 02:05:40 EST
References: <1882@uwmacc.UUCP> <682@bonnie.UUCP>
Organization: AT&T Bell Laboratories
Lines: 33
Xref: watmath net.audio:7151 net.auto.tech:599

> > 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