Alternator whine via amplifier

[Max399]

Hello,

I've got a 88' 318i. When i bought it from Germany - it had a pre-installed Kenwood stereo system which consisted of the Main unit, front and rear amplifiers and speakers.
I have removed everything from that setup ever since, but i reused their wiring.
I've wired a Blaupunkt SF320 stereo - it has it's own power cable directly to the battery. In the rear i've got a Blaupunkt GTA270SF, it also has a direct power cable to the battery and two grounds - one on the chassis in the trunk and another one on the rear shock bolt.
It all sounds OK when the car is not started, but when i start it - i get that high pitch alternator noise..
I had ordered a noise suspenser form Ebay, it looks something like this:


I gues it worked - but the bad side of it is that it absolutely cuts all of the bass. Even with maximum gain on the bass it has no bass..
What should i try do? Any suggestions?

Max.

[jlevie]

To fix this you need to add RFI filtering on the power lead to the equipment and to any other lead that has a connection to the car's electrical system.

[AndrewBird]

Ground the amps as close to the amp as possible. Sand away the paint and use a self tapping sheet metal screw. Make sure all signal wires (RCAs) are away from power wires and if they have to cross, make sure they cross at 90º.

Those filters IMO are a band-aid fix for the problem. You shouldn't have alternator wine if everything is installed correctly unless something is damaged.

[Max399]

Thanks guys, will see how the cables are routed, maybe theres an issue with that.

Max.