Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 72Blazer on July 01, 2024, 05:41:25 pm
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Another one of my builds. Stock except reverb and tremelo in both channels, a master volume (Post phase inverter), and multi-tap (selectable switch installed) output transformer
Amp was working fine with the exception IMHO that channel 2 was not nearly as loud as channel one. but has developed a hum and distortion in BOTH channels when strings are played.
I have put in new matched set output tubes (rebiased the amp) and switched in and out different preamp tubes in all positions. No effect whatsoever on this distortion accompanying the strings/notes played. I’ve reflowed many solder joints and verified good ground connections.
Rectifier putting out 390VAC. Schematic shows ~360v
340v on the output tubes and biased at a cool 19mA. Voltage on the schematic shows it should read ~460v.
Any ideas where else I should check?
EDIT: The issue was that one of the filter cap wires (red one going to the far corner of the eyelet board) came loose.
Channel 2 is still not quite as loud as Channel one. Channel 2 pegged is like channel one on 6. Can't figure this one out.
Vr
J.