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Path: utzoo!aesat!bmw
From: bmw@aesat.UUCP (Bruce Walker)
Newsgroups: net.audio
Subject: Re: Auto cassette deck vibration - !@#%$
Message-ID: <385@aesat.UUCP>
Date: Wed, 1-May-85 08:14:09 EDT
Article-I.D.: aesat.385
Posted: Wed May  1 08:14:09 1985
Date-Received: Wed, 1-May-85 09:25:48 EDT
References: <14700017@hpfcms.UUCP>
Reply-To: bmw@aesat.UUCP (Bruce Walker)
Organization: AES Data Inc., Mississauga Ont., Canada
Lines: 41
Summary: 

In article <14700017@hpfcms.UUCP> bill@hpfcms.UUCP (bill) writes:
>I recently saw a note in net.audio concerning vibration noise in car
>cassette decks.  Well, I'm on my fourth deck in my car (a Ford Tempo '84)
>and I've just about given up on listening to my tapes.  The vibration is
>horrible.  It seems to occur in the frequency range (4k-8k hz?) where
>alto saxes, high male or females voices, piano, oboe, etc. live.  The
>first three decks were Alpine, and the current deck is a high-end Yamaha.
>
>Bill (stop the car - I want to listen to a tape) Gates
>hpfcla!bill-g

You may be changing the wrong component; try a new car. :-)/2

I wrestled with that problem in a car I owned a couple of years ago.  I had
a Panasonic (not particularly hi-end) system which was too big to be placed
in-dash so I mounted it beneath the glovebox on a little shelf that the car's
maker (Mitsubishi) had stuck there for some unknown reason.  Everything was
fine until you hit about 55mph (90kmh) at which point wow & flutter values
were about 100%.  So I removed the shelf and used it as a template for a 7/16"
plywood replacement reinforced down the front with a piece of 1.5" on-a-side
by 1/8" thick steel angle-"iron".  This whole affair was securely mounted to
the car's chassis with the aid of 3/8" threaded rod and whatever else was
necessary to mechanically couple the deck to the car.  The theory is: either
completely decouple the unit with viscous damped shock absorbers (I couldn't
find anything readily available) or else *tightly* couple the unit to 
something whose vibration rate is low, in this case the car's chassis.  You
want to avoid having any mounting arrangement which allows some free movement
in any axis which would allow mechanical resonances to occur.  Also avoid
mounting to anything which is coupled in some way to the engine (firewall,
perhaps, or transmission hump).

Anyway, my mounting method worked reasonably well, and probably increased the
burgler-proofness as well.  On my current car, I searched high and low to come
up with a unit that would fit in the dash.  This way, the unit is inherently
well mounted up front and only needs reinforcement behind.  I have had no
problems with this arrangement.

Bruce Walker     {allegra,ihnp4,linus,decvax}!utzoo!aesat!bmw

Accuracy Disclaimer:  I am not a mechie, so take these comments with a grain of
		      silicon.