210-65 2275-65 squeal

Alpha Dog

Replaced all electrolytic caps, new glass, new reverb tank, sounds fine until you get gain over "7" and then it squeals, like a self generated feedback loop. I would not think this is "normal", I must be missing something somewhere.... Suggestions? Thanks!

Full Name
Rob Flindall
Music Man Equipment
112RD-100 with EVM speaker, built 1981

Member for

10 years 1 month
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RD112 Sun, 09/15/2024 - 08:20

See the Service Bulletin #1 available in the Downloads & Resource Section of this Site.  You may need to adjust the output tube cathode bias.  There is a small trim-potentiometer on the circuit board.  What you describe sounds like it might be a cross-over distortion/feedback.