Whining new tweeters

Got my new tweeters + front 6,5" + filters mounted this summer. Very nice..
BUT, now I got a whine in the tweeters going with the engine's RPM, no matter if the stereo is on or not. Very irritating!
Is this common, and what should I do?

I had this in another car, was told is a need for a supressor.

Probably a suppressor (sp?) for the alternator required - that would rise and fall with the engine speed.