Drive requirements.....

[rsumperl]

If I have a set of push-pull tubes biased with -50v, if I want to drive them into AB2, will the drive need to be at least 100 p-p?


Thanks,
Ray

[roline]

What are the tubes, and load line; transformer resistance and power supply?

[bob91343]

If you want to drive the grids positive, and draw grid current, yes you need more than 100 v p-p to accomplish that.

[SemperFi]

As mentioned, u need to swing the grid above the cathode potential, so u need more than 50volts each way as mentioned. But if the OPT is for AB driving, the impedance is likely too high for any benefits of AB2. The plates will saturate (too low voltage) before the positive going grid can do any good to the plate current.
U could try to hook a lower impedance load to a higher impedance output tap, such as a 4ohm speaker to 16ohm tap, which probably works, but the OPT may not be dimensioned for the increased current at max signal.