Here is the circuit diagram of Baxendall tune control circuit. The name Baxendall for this circuit is because this circuit is based on the tune control circuit developed by Baxendall. This circuit uses two transistors Q1 and Q2 (BC 109C) which are the central active components in this circuit. This circuit can produce a maximum cut or boost of around 12 dB at 10 KHz (treble) and 50Hz (bass).
The whole circuit consists of three stages such as input stage, Baxendall circuitry and output stage. The input stage is an emitter follower centered on transistor Q1 and consisting of resistors R1 (560K), R2 (470K) and R3 (2.2K). This input stage has unity gain and the output of this stage is fed to the Baxendall stage through the capacitor C1 (10 uF). Potentiometers R7 and R10 (47K) are used for the adjustment of bass and treble respectively. The output stage of this circuit consists of transistor Q2 and resistors R11 (2.7M), R12 (10K) and R13 (2.2K). The output of second stage is given to the output stage and the final audio output is produced from the output stage with a gain of three.
- Assemble the circuit on a good quality PCB.
- A 12V DC supply is used for powering this circuit.
- Both the bass and treble can be independently adjusted.
- The input stage of this circuit has an impedance of 225 kilo ohms.