> so i put a new stereo in the beast yesterday.  home built kicker box,
> nice amp, nice head, reasonable three ways.  sound good. sounds good.
> sounds good!!!! [say that to yourself, it won't make any sense after a few
> repititions...kinda like 'egg']  anyway i'm getting interference.  there's
> a high wistle from the tweeters that follows engine rpm.  how do i make it
> go away?

This is indicative of a loose ground connection. Make sure that 
  1) the ground wire is of the same gauge as the power wire, and that both
     are of sufficient guage for the power required
  2) ensure the connection of the ground wire is one of the following:
     a) directly to the battery terminal
     b) to the chassis in a spot that you cleaned thoroughly with a
        wire brush as paint does not conduct well
     c) if you are using someone else's ground wire, make sure there is
        no other electrical device using the same wire, I recommend 
        switching to method "a" or "b".
  3) the ground wire is securely screwed in tightly at both ends
  4) make sure the amplifier's box is not making an additional contact
     with the ground wire or the chassis... having two paths to ground
     can be troublesome if one of them is intermittent
  5) make sure the leads on the ground wire are clean

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Joshua R. Poulson, Systems Engineering, ADP Dealer Services, Portland, OR