There are many things I want to try the circuit to experiment with different ideas. Replaced parts values, modify settings, or other circuit. As a result of this circuit. 12AX7 preamp tubes built. Very nice pleasant sounding. It reminds me of amplifiers in the 60s. Good guitar setup, the “bright” metallic voice.
The circuit runs on 12V. Since such a low voltage, low gain, it is necessary to supplement MOSFET amplifier circuit. MOSFET similar characteristics as triodes, so his voice is not as annoying as a transistor circuit.