Simul's "Class A" question

[edward]

Sorry if this has been explained before, but just how does a SimulClass' "Class A" switch bring the EL34 pair down to 15 watts? This is for a pentode (greenie), if that matters. Thanks!

Edward

 

[JOEY B.]

The pentode (green stripe) will be a 25/85 watt switching system. Think of it like this: The inner pair of tubes are wired in class AB pentode and provide 60 watts of power. The outer pair are wired in the "MESA Class-A" pentode and provide the other 25 watts. When the switch is moved to Class-A, the ground is lifted on the inner pair of tubes, rendering them inactive. I hope this helps. 8)

 

[edward]

Thanks, Joey. Makes sense! So if I modded via add'l switch to make the outer pair switchable between pentode and triode, it would bring it down to about 15 watts?

Another thought: could the outer pair of ELs be wired so it could be switchable between stock Class-A and AB so as to have a bit more headroom but not go into Simul mode?

Edward