09-07-2015, 12:05 PM
I have found the distortion model V4 to be sensitive to oscillations. I usually add screen resistors and move the grid resistors to the power tube sockets.
But that doesn't mean that is what you are experiencing.
I know you were very meticulous in changing out components, but I would check the values again, and make sure your solder joints are clean.
you can also narrow things down by removing preamp tubes. I would start with V5 (12dw7) and if it continues, pull V201 (6AN8) if it continues then it is the power tubes and you should do the things I listed above. (they should probably be done either way)
But that doesn't mean that is what you are experiencing.
I know you were very meticulous in changing out components, but I would check the values again, and make sure your solder joints are clean.
you can also narrow things down by removing preamp tubes. I would start with V5 (12dw7) and if it continues, pull V201 (6AN8) if it continues then it is the power tubes and you should do the things I listed above. (they should probably be done either way)