Path: utzoo!attcan!uunet!lll-winken!ames!ncar!stout!cook
From: cook@stout.ucar.edu (Forrest Cook)
Newsgroups: sci.electronics
Subject: Re: Define "GROUND" (& how to solve a "GROUND" loop prob)
Keywords: ground, loops, earth, ship, plane, audio
Message-ID: <3299@ncar.ucar.edu>
Date: 26 May 89 19:41:17 GMT
References: <3917@merlin.usc.edu> <3297@ncar.ucar.edu>
Sender: news@ncar.ucar.edu
Reply-To: cook@stout.UCAR.EDU (Forrest Cook)
Distribution: na
Organization: Field Observing Facility, NCAR, Boulder, CO
Lines: 37

In article <3297@ncar.ucar.edu> cruff@handies.UCAR.EDU (Craig Ruff) writes:
>In article <3917@merlin.usc.edu> cyamamot@nunki.usc.edu (Cliff Yamamoto) writes:
>>BUT by just merely connecting the car body ground ONLY to the ground of
>>the stereo, I get all kinds of motor/ignition noise.

>I've got this same problem.  Luckily, the level of the ignition noise is low.
...
>Currently they are grounded to to different points on the frame.

 ^^^ Currently?  maybe you have stray ground currents floating in the frame.

 But seriously, folks, the problem could probably be solved by electrically
 isolating the power amp from the car frame using plastic washers and running
 a heavy gauge ground wire to the receiver or the place where the receiver is
 grounded.  This can be tricky sometimes so I would recommend mounting the amp
 and checking for no continuity to ground before wiring it up.

 The amp's +12V line should probably be connected to the same place as the
 receiver's +12V line if possible.

 You might even try disconnecting the ground side of the audio line where it
 enters the receiver.  This may make the noise worse but it's worth a try.

 The goal is to only have one (preferably short) ground path between the amp
 and the receiver and to remove any other ground connections.
 Make sure that the speakers wires are not grounded anywhere, they should
 only connect to the amp.

 Shielding speaker wires is probably as effective as plating them with mercury
 in normal environments :-) :-)  (see the sci.electronics archives)

 Good Luck

 ^   ^  Forrest Cook - Beware of programmers who carry screwdrivers - LB
/|\ /|\ cook@stout.ucar.edu (The preceeding was all my OPINION)
/|\ /|\ {husc6|rutgers|ames|gatech}!ncar!stout!cook
/|\ /|\ {uunet|ucbvax|allegra|cbosgd}!nbires!ncar!stout!cook