In Reply to: E34 & new sound system problems posted by Dave on April 03, 1999 at 21:01:28:
You have a bad ground somewhere - track that down and /or run a large (10+ ga ground from a single point to all components of the system. ONLY by solving the ground problem (and thus killing the very small current that causes ground loops) can you kill the whine. Mine was at the factory ant. amp that allows use of the rear defrost as the ant.
You can search the net for "ground loop" and get plenty of detailed info on this.
: I'm having two problems with the new stereo I just put in an 89 535i I just bought. I had the same probs with an 89 525 I used to have, but this time I want to solve them. Does the factory antenna run through the factory amp? I removed the amp, and now get zero reception. Also, all locations in the car cause ground loop noise (alternator whine) in the system if the gain is above min. on the new amps. I've tried many ground points, routes for the rca cables, twisted pair interconnects, loop isolators, etc. Has anyone else had this problem and solved it? E-mail please, thanks.