Audio Suppression Problem

[D'Ecosse]

I have an aftermarket amp & speakers (MTX Thunder & Image Dynamics speakers & sub) that came with the car when I bought it.
Reagrdless of radio (am or fm) or CD, there is an interference issue when the engine is running, presumably lack of suppression. Any suggestions on where to start looking, or components I could add?

 

[Kinan]

Is it a whining sound that changes with engine speed and/or electrical load? Does it get worse when you turn on your headlights?
If so, you probably have a ground loop ie. an indifference of ground reference between your head unit and your amp that gets amplified as audio.
Recheck all of your ground connections and try to tie your head and amp grounds as close together as possible.

 

[scott]

I had the same problem. If your amp is mounted in the trunk and the RCA cables run to the amp by the alternator you will pick up alternator noise. You must run shielded cables. Note not all cable you buy are truly shielded, including monster cables etc. The best solution is shielded twisted pair, two wires with a shield. Connect the amp and the head unit with the twisted wires. The ground for the units will be one of the twisted pair. Connect the shield to a chasis ground close to the amp on the amp side and close to the head unit on the head unit side. I ended up shielding my regular RCA cable with braided radiator hose and grounding both ends to chasis. Also make sure your amplifier ground wire is short and fat.