On modern ("class A/B" or better "push and pull"?!?) poweramps there is one preamp tube (two triodes) need as a phase inverter...kaomao said:hey guys my old rack poweramp had a 12ax7 valve on it and four EL34.
12ax7 was used as driver, don't ask me what's a driver in the poweramp though...
to describe in a bad way... there are alway 2 (or 4 or 6) tubes in a poweramp one is "pushing" and one is "pulling" the signal...
so one of both needs to get the inverted signal as input... ah better read this in a tube amp book ... I can't describe very well