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From: ben@catnip.UUCP (Bennett Broder)
Newsgroups: net.auto.tech
Subject: Re: Summary: Car speaker problem
Message-ID: <257@catnip.UUCP>
Date: Sat, 8-Mar-86 11:53:27 EST
Article-I.D.: catnip.257
Posted: Sat Mar  8 11:53:27 1986
Date-Received: Sun, 9-Mar-86 08:30:40 EST
References: <2003@uwmacc.UUCP> <1049@psivax.UUCP>
Distribution: net
Organization: The Broder Residence, Holmdel, NJ  07733
Lines: 46
Keywords: Polypropelyne speakers, paper speakers

In article <1049@psivax.UUCP>, tommie@psivax.UUCP (Tom Levin) writes:
> In article <2003@uwmacc.UUCP> jwp@uwmacc.UUCP (Jeffrey W Percival) writes:
> >Problem: Car speaker (Pioneer ts-411) had a raspy noise, correlated
> >with bass notes.
> >
> >Possibilities:
> >4. Warped cone, rubbing on the piston.
> >   Bingo.  The cone material is a paper-like substance, and
> >   moisture from the trunk area plays havoc with speaker cones.
> >
> >There's no fixing this problem, so I'm shopping for new speakers.
> >Some people recommended speakers with polypropylene cones.  A
> >membranous material that looks highly resistant to moisture.
> >All the good manufacturers make some models with this material,
> >and I think I'll go with that to avoid buying speakers every
> >two years.
> 
> Indeed, polypropylene is water proof as well as temperature proof.
> Thus, it is an ideal material for a car speaker.  
> 
> There is an alternative, though.  For those of you who have paper
> speakers, why not make them water resistant by treating them?
> Go to your nearest art supply store and buy a small bottle of 
> "Acrylic Mat Medium" along with a small paintbrush.  Apply a THIN 
> coat (you don't want to change the speaker's mass significantly) 
> to the speaker.  Not only will this make it water proof, but it will 
> also "clean up" the mid-range quite a bit!  This is an old trick in
> the speaker biz to make cheap drivers sound better.  It works because
> you "stiffen-up" the driver without adding much to it's mass.  Are
> you skeptical?  Well, Polk audio does this with their loudspeakers.
> They buy cheap paper drivers and then treat them with "plastiflex".
> I have used Acrylic Mat Medium on more than one system I've built
> (both home and audio) with excellent results.

Be aware that there is a risk in this procedure.  The acrylic mat medium
can cause the cone to warp (in much the same way as the water would), and
you can find yourself with a brand new speaker with a voice coil that rubs,
and absolutely no recourse.  Speaker manufacturers who produce doped cone
speakers apply the dope and allow it to dry completely before the speaker
is assembled.

-- 

Ben Broder
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