I have a 1980 2204 that I had bought 20 years ago and at the time it was a basket case (and sat in the basement until a few weeks ago). After aquiring a good scematic for this amp I was able to revive it back to life. It was a bit noisy (pots were nasty) and it was making a buzz type noise which would be minimized if I turned down the tone knob on my guitar. I verified that it was not my guitar by using another one and had the same results. I have replaced all of the pots and and the filter caps figuring that I may eliminate most if not all of the noise. The buzz type noise is still there. The new pots & caps have improved the overall sound bit did not eliminate the noise. Where is a good place to start? I have not biased the amp as of yet. If the bias were to be out of whack could that cause the noise? Any and all help would be appreciated.