Power tube usage

[aaronlyon]

There are four power tubes in the Mark IV, labeled A through D. I currently have EL34s in the two outside sockets, A and D, and 6L6s in B and C. When are the EL34s used? Only in Simul-Class? Always?

Is the Mark IV tube or solid state rectified? I don't see a rectifier tube…

 

[MrMarkIII]

A and D are used in Simul-Class (with the 6L6s, 85 watts) and by themselves in Class A, 25 watts.
The rectifier is solid state.