I have the buzzing problem with my F-14 also. It happens to have a Rotten Dog MPU in it as well. I learned in another thread that this is somewhat common with the RD MPU. The sound quality on mine is sub par as well. I currently have a Williams board out for repair and am hoping that once I get it back and installed, that the sound improves on my machine.

I get the buzz on startup about 80% of the time. I never get the "bong" that you get with the Williams board. I then get this weird fluttering background noise. No circus music though.