the amp in question is homemade and home-designed.
you are correct about the turns ratio.
the top of the input step-up transformer secondary is connected directly
to the grid of a 71a. the bottom is connected to ground.
the primary is connected to the input jack and is completely isolated and floating from ground.
at present there is no resistor across the secondary.
i expect to experiment with different values of resistors at this location though.
the transformer is actually a linestage output transformer, connected as a step-up input, and i have been driving this amp with an active linestage that uses the same transformer on it's output. so in effect i have the linestage and the power amp coupled via two identical transformers, mirroring each other.
nevertheless, the amps just sound so much better when i omit the active linestage altogether, and i don't need the gain, so i want to try passive.
And I think the tx102 might be the way to go.
thanks for your help.
best,
- k