check your wireing. make sure that no bass is getting to the tweets and check to see that your amp is set to a high pass x over. wouldnt hurt to check your ground wire either.
What kind of buzzing? High pitched low pitched? Is it constant or does it change with music or the beat, if you turn the volume down is it still there? have you played with any of the wires yet to see if it goes away? (RCA and speaker wire)