97 Altima Alternator Noise

We have a customer with an Aiwa head unit, pioneer speakers, and a jensen amp (yes I know, yuck all around).  He has the amp running the back 6x9s, and apparently ever since it was installed there was always alternator whine running through the back speakers.  Now just a few days ago he started having a new problem where there is a REALLY loud rumbling that seems to be somewhat matched to the rpms of the engine, but it is really so loud that you have to turn the car off right away.  Adjusting the volume control on the head unit does not decrease the volume of this rumbling.  I put a ground loop isolator on the RCAs that go to the amp, and that seems to have gotten rid of the rumbling, but the alternator whine is still there.  Any ideas as to what's goiing on? 

What is the amp's gain set at ? If too high it will induce noise alot easier than if lower. Set to a lower level if the gain is above 3/4 and see if this helps the situation. Otherwise I would say it is related to ground of the amp or the deck.Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

Also double check that the rcas and power are at least run 18 inches apart ( opposite side of car would be better).Certified Security Specialist

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