• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

6(12)SN7-6n8 at 3...4ma anode current

6A3sUMMER,

The 20.5 gain stage was measured on unloaded transformer, so it should be (almost) equal to u.

It's possible the model might be off with a .5 gain. Which in real life is completely normal.

The 47k loaded stage will be of course, lower.

I used LTSpice for this with an Ayumi model