Spent the last 3 days doing a full audio rewire on my car.
New cables direct from every speaker, new head unit (no seperate amp) and im getting alternator whine 
I have bought, and fitted an inline
"power noise filter" which has reduced the whine by about 80%, but its still there.The new cabling includes direct fused battery feed for the power, bypassing all the old premium wiring.
I have disconnected all the old stock amps, and removed the audio loom that went from behind the passenger to the dash.All cable joints are soldered and heatshrinked, and all speaker polarities have been double checked.
Anyone got any suggestions for me?
im stumped and a bit irritated nowEDIT
- gonna clarify somethingThe new power cabling has the ground lead from the HU going straight onto battery negative.
I have a large single positive feed from the battery, going into a little box I built. This box contains a 2a fuse and a constant 12v output for the stereo memory. The input is also split to another 30a fuse, then through the contacts of a relay then off to the HU as the "Ignition" power. The relay is powered from a seperate 12v feed I tapped into from the ciggy lighter, so the relay is only activated when the ignition is on, engaging the contacts and completing the circuit to the "ignition" power for the HU. This relay seperates the systems and means im not pulling silly power through the ciggy lighter circuit to power the radio.I have tried removing this box to see if it was that causing the whine, but it made no difference at all
