allanhurst:
Gain of each stage?
I've just done a simulation and the first stage gives a max. gain of 40dBV @ 60kHz interestingly. That's about 100x. Plate resistor was only passing 1mA. I'm not sure how accurate my EF91 model is, especially in the edge cases with such low currents.
I feel better now that it's a realistic circuit. I'll have to rejig the capacitors to extend the gain to Arduino ADC frequencies. Better get building...