Audio Systems: Engine noise, vw golf 2, sony head unit

Question
Hello, '95 VW Golf 2-door
I recently upgraded my car stereo in a couple of phases, and on the last installation I now have very loud engine whine.
I first had an MA Audio 800W 4ch amp installed to my Sony head unit and Sony 10-disc Changer with stock speakers, no noise. Next I installed a Audiobahn 10-inch tube, bridged across the 3-4 channels, sounded great, no noise. Finally I installed  a Pioneer head unit and Pioneer 12-disc changer and now with the engine running, I get the whining with rpm's.
I was an IBEW electrician apprentice, I have sucessfully re-wired several cars, and have done plenty of stereo installations, but I can't figure this one out. I ran The RCA lines directly from the HU to the amp on the other side of the car, still noise. I hooked the ground from the HU directly to the neg battery, still noise. I hooked the ground from the amp directly to the neg battery, still noise. I do have an aftermarket amplified antenna from a an Acura MDX, but the thing is that I had no noise until I installed the Pioneer Head unit and Changer.

Answer
Hello Big Wil,
The whine is comming from the alternator. Due to the amount of heat under the hood it can cause the internal filter inside the alternator to fail and the amp is picking up the AC ripple noise from the alternator. For a clean sounding sound from the amp/s you can purchase a high current filter that is rated at least as high of amperage output of the alternator and install it on the output terminals of the aternator as per instructions that come with it. This external filter will cost on the aperage $50-$60. As for the whine being heard only with the Pioneer unit, this is due to some head units not having as good of a filtering network inside the stereo and this is causing the noise to pass thru your stereo system.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net