Alternator whine in radio

When driving I can hear a slight whine in the radio that varies with rpm. I can only assume it is coming from the altenator... any ideas?

is this aftermarket stereo? or stock?


In general, i'd check all you're grounds...make sure they're solid grounds.

If it's aftermarket and you're running seperate amps for speakers.....don't run your rca cables with your power cables....preferably rca's down the middle and power down teh side of the vehicle.....