Mark IV preamp tube functions

[boola]

ok, so the Mark IV manual says:

V1a = Input
V1b = Tone recovery

V2a = 3rd gain stage (rhythm) and 5th lead gain stage
V2b = FX return

V3a = 1st lead gain stage
V3b = reverb return

V4a = 2nd lead gain stage
V4b = reverb send

V5 = phase inverter

I was wondering, what are the 2nd rhthm and 4th lead gain stages?

 

[4Eyes]

V1a = Input (1st rhytm and lead stage)
V1b = Tone recovery (2nd rhytm and lead stage)

V2a = 3rd gain stage (rhythm) and 5th lead gain stage
V2b = FX return

V3a = 1st lead gain stage (3rd lead stage = 1st lead GAIN stage)
V3b = reverb return

V4a = 2nd lead gain stage (4th lead stage = 2nd lead GAIN stage)
V4b = reverb send

V5 = phase inverter

 

[MrMarkIII]

I was wondering, what are the 2nd rhthm and 4th lead gain stages?

They only pop into existence out of the vacuum flux when the Schroedinger Wave Function collapses.