So I started working with troubleshooting a channel imbalance on the schematic attached, 12ax7 + 6L6GC push pull. But the problem seems to be a bit different...

My voltages seem to be a bit hot!! (a lot hotter I think...) V2 is even higher than C16 450V rating :S

Please see attached. Any locations/components I need to check first? Thanks a lot.

power supply voltages

channels and feedback

full schematic

  • \$\begingroup\$ An unregulated PSU like that may well supply more voltage when unloaded, so it's possible your tubes are not drawing their intended current. Which could be cool heaters, duff tubes, bias too negative, broken resistors. Compare the two sides, if you're lucky only one is dodgy and you'll see big differences. \$\endgroup\$
    – Neil_UK
    Apr 10, 2019 at 9:18
  • \$\begingroup\$ one side has a bit of a wobbly output. 1khz/300mV input test on 8Ohm dummy loads. this is where my investigation started. To be honest im not sure what to expect in terms of voltages. Some other "120W" amps seem to have similar voltages. But it seems over specs (for the caps) \$\endgroup\$
    – OHTO
    Apr 10, 2019 at 9:43

1 Answer 1


After reviewing tube amplifiers with similar power supplies (identical probably) the voltages seem ok. There is a little variation between channels but I think its within normal operation.

From "Peavey-Triumph-Schematic.pdf"

enter image description here

  • 1
    \$\begingroup\$ Are you posting this as an answer to your own question? If not the information should be edited into your question and this post deleted. If it is an answer then you can accept it after a time delay to indicate that it is solved. \$\endgroup\$
    – Transistor
    Sep 19, 2020 at 17:43

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