Here is Steves schematic using 6973 valves using the same transformers as the schematic for the EL84. Notice that the B+ voltage is 347V at the plate of the 6973 and 330V at the plate of the EL84/6BQ5. Steve sometimes is not worried to push the valves a bit. 300V is the max rated voltage for a EL84. I have run them a little hotter in the past without issue. As I remember the plate voltage in one of Bruce Zinky amps runs over 300V.

There is a resistor change in the power supply that is not on the schematic.







Billy

Last edited by Planobilly; 07/23/23 08:21 AM.