02-21-2018, 08:18 PM
Thanks for the reply jjmt,
The plate voltage is the same on all the power tubes. I did mention above that I drove the output section with a Marshall 2203 transformer only to recreate the same red plating scenario. Also, in one of the amps, I replaced the PI socket as well as the output tube sockets with brand new ceramics. Further, I replaced all wiring from the main PCB to the sockets to rule out any intermittent break in a wire.
The output tubes were very closely matched before adjusting the overall bias, and I also matched the triodes of the phase inverter on a curve tracer.
Thank you for your comments and keep them coming!
The plate voltage is the same on all the power tubes. I did mention above that I drove the output section with a Marshall 2203 transformer only to recreate the same red plating scenario. Also, in one of the amps, I replaced the PI socket as well as the output tube sockets with brand new ceramics. Further, I replaced all wiring from the main PCB to the sockets to rule out any intermittent break in a wire.
The output tubes were very closely matched before adjusting the overall bias, and I also matched the triodes of the phase inverter on a curve tracer.
Thank you for your comments and keep them coming!