This simple tone control circuit is designed based on the famous Baxendall tone control circuitry. The circuit given here can give a maximum cut or boost of around 12 dB at 10 KHz (treble) and 50Hz (bass). Also, both bass and treble can be independently adjusted.
Transistor Q1 (BC109) and its associated components (R1, R2 and R3) form an emitter follower which is the input stage. The voltage gain of this input stage is around 1 and it has an input impedance of around 225K ohms. The output of the input stage is coupled to the passive Baxendall circuitry using the capacitor C1. POT R7 can be used to adjust the bass and POT R10 can be used to adjust the treble. Transistor Q2 and associated components (R11, R12 and R13) forms the final output stage which gives an overall voltage gain of three to the system.
- Assemble the circuit on a good quality PCB.
- The circuit can be powered from 12V DC.
- POT R7 can be used to adjust the bass while R10 can be used to adjust the treble.