Alternator noise to power AMP

Ben Swann benswann at
Mon Apr 4 22:40:52 EDT 2005

Maybe I need to better address the grounding at the stereo(pre-amp) -
although it does go to the common ground point at the driver side kick
panel.  Don't have the grounded sheild cables - I would need to get an
inline sheild adaptor to keep from having to re-run my wires.

----- Original Message -----
From: "Huw Powell" <audi at>
To: "Ben Swann" <benswann at>
Cc: <urq at>; <quattro at>
Sent: Monday, April 04, 2005 7:44 PM
Subject: Re: Alternator noise to power AMP

> > After recently wiring in a power amp to the rear speakers for my '83 Ur
> > Quattro, there is a whine being picked up by the RCA inputs to the amp.
> > is not picked up by the stereo, front speakers, or if rears are wired
> > directly to the stereo without an amp.
> >
> > How can I eliminate this or filter it?  I am using high quality RCA
cables -
> > don't know if they are sheilded.
> Try rewiring your grounds so they are all attached to the same place.
> Also, "directional" RCA cables (shield only attached to ground at
> pre-amp end) can help.  On my coupe I ran ground cables forward from the
> amps to the shifter mounting bolts, and also grounded the head unit
> there.  On my 90Q I ran a ground wire back from the head unit to a
> bumper mount bolt in the trunk where I grounded the amp.  Neither car
> has any appreciable ignition/alternator noise, which is nice.
> > Also, what kind of capaciter would be good to eliminate powere clipping?
> Although I know people seem to love their 1 F etc. caps in the trunk, a
> good heavy power/ground cable ought to be enough - your battery is one
> heck of a charge storage device...

That is what I thought, but still seems to pop when powering on and when
cranking a lot of bass drum, seems to drop out.  I don't necessarily trust
this amp(not new), and it may be an internal thing.
> --
> Huw Powell

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