Whining noise in stereo - how to fix?

gaz_69, Jun 13, 5:30am
Hey guys,

I have an awful whining sound in my stereo, and nothing seems to fix it.
The noise is only present when the car is running. The noise fluctuates with the RPM.

So far I have done the following;

Made sure there are no power cables near the RCA leads.
Checked all the earths and sanded back the paint so there are nice grounds everywhere.
Added ground loop isolators to the amp. (made no difference apart from making the music sound sh1t)
Added a noise suppressor thing to the head unit. (did nothing)
Currently I have no aerial as I shaved this off when I rebuilt the car.
I don't know if this is relevant, but when I removed the headunit ground (battery still connected) A different type of hideous whine was emitted through the speakers even though the stereo was off (no faceplate)
Anyone have any suggestions of other things I can try!
Cheers
Tom

twaymouth, Jun 13, 5:39am
Have you checked the noise suppression capacitor on the back of the alternator! If you have already added a noise suppressor to the head unit then this may not matter but it might be worth a look.

gaz_69, Jun 13, 5:43am
Hmmm, didn't know there was a noise suppression capacitor on the alternator. How would I check this!

twaymouth, Jun 13, 5:47am
It will be a little round cylinder or cube like this: http://i77.photobucket.com/albums/j76/basslyne/altques2.jpg However not every alternator has one. If your alternator has one then you can try replacing it and see if it helps.

johnf_456, Jun 13, 6:01am
Are your RCA leads and power for the amp running down separate sides of the car!

gadgetman, Jun 13, 6:08am
To test if it is coming from the alternator, you could disable the alternator by running without fan belt just long enough to test if the whining is gone!

richms, Jun 13, 6:58am
Is the ECU directly under the headdeck! Could be injector whine not alternator.

Anyway, take the ground for the headdeck back to the same location as the amps ground instead of using the one in the loom and see if that helps.

iman007, Jun 13, 7:01am
its prolly johnf45678, frig, he could whine for new zealand!
and win!

lmfao

johnf_456, Jun 13, 7:34am
Lmfao care to help the op!

iman007, Jun 8, 12:13am
you could do with an op,
frontal type!