Greetings from MD!
I have a really basic question about output tubes: How does one know what the maximum driving voltage should be from the pre-amp?
As an example, I am building a mono-block 6L6GC P-P amp, and want to get the max clean output from my tubes. Is there a way to know what the maximum voltage swing I need at the 6L6 grids -- other than by trial and error?
Bias voltage X2 is a good place to start. i.e. if you have 40V on the cathode or -40 bias on the grids, 80V PP is the theoretical max swing that output tube can handle without the grid going positive.