How to create a tone control audio clean, gently, but firmly? always wore these transistors.
The first transistor (left side) acted as a buffer. Provides circuit with high input impedance, around 250k has a voltage gain of slightly less than unity. As Baxendall tone control circuit is a passive design, all audio frequencies are attenuated. Position tone control audio and reactance of the capacitor change the tone control audio response. Last Transistors give a little push around 3x. This output is designed to feed an amplifier with input impedance of 10k to 250k. Both tone controls should type linear potentiometer.