Valve amps - push/pull configuration?

[the record spot]

I've read about older valve amps having a push/pull configuration. I think this relates to the valves themselves, but don't know what this means - can anyone out there come up with an answer perhaps?!

 

[drummerman]

Modern high power output stages are usually push pull, often necessitating some form of phase splitter to derive a differential/balanced drive signal from a single ended input, typically followed by a further gain stage (the "driver") prior to the output tubes.

Single ended" power stages using very large valves exist and dominate in radio transmitter applications. A sidebar is the observation that the niche "DH-SET" (directly heated single-ended triode) topology favored by some audiophiles are extremely simple and typically constructed using valve types originally designed for use in radio transmitters

 

[Anonymous]

You can get more power out of two tubes than one. You may be surprised to learn that you can get more than twice the power out of two tubes in push-pull then you can get out of just one. In simple terms it's like two people cranking a human powered winch. There are two cranks, one on each side of the winch. The two cranks are 180 degrees apart and just when one man gets to that part of the circle where he is lifting and pushing away on the crank (his weakest point) the other man is pulling down and toward himself (his strongest point). It works much the same way with two tubes in push-pull. They are working 180 degrees apart and when one tube is in a condition where it is making the weakest contribution to the power the other tube is at its strongest.