The Drive Channel is fed from the input stage, via selectable Gain potentiometers. There is a tube assigned to this channel, V2, that uses one of its two triodes to drive a Treble-Bass-Middle tone stack, followed by a Master Volume potentiometer.
I’ll talk about the tubes I’ve tried here, later. Note: it is a combination of tubes in V1-V2-V3 that have to be considered, as the tubes in V1 and V3 have an effect on both the Normal Channel and the Drive Channel.
For later:
V1 EH-AY7 – V2 EHAX7 – V3 Sovtek-WB settled on this combo because of different voicing for AY-AX V4 T5 B7 M4-2 G7 G5 MV4 – start with MV same as V then tweak Gains for voice – use drive channel for mid and neck pups
RSAX7C Grind; in V2 following V1-12AY7 there is a distinct voice to RSAX7C but overdrive tends to be a bit fizzy. GT-AR-RB in V3.
RSAT7C TS-9 – Surprisingly good choice for V2, not as much bottom as V1-12AY7 but okay boost with a hint of overdrive, especially at higher gain
Tried EH-AX in V2 but swapped into V3 for JJ-83 20131006
JJ following Sov-LPS better volume than EH but clean – 20131006
JJ following EH gives better low volume grind than EH following EH – 20130715
FMI 93 Super Amp 