A very simple and useful tone control circuit diagram is presented in this schematic . This tone control circuit is designed using PT2350 tone control subwoofer cross-over low pass filter chip (using CMOS Technology) , manufactured by Princeton Technology Corporation .

PT2350 tone control circuit features a tone control range of + 10dB (50Hz, 4 KHz) and subwoofer low pass filter of the second order Sallen Key Design. The roll-off point can be adjusted by changing the value of the external capacitor.
PT2350 tone control main features are : 2 - Input Channels, 3 - Output Channels (Including 1 stereo Output and Subwoofer Output), Low Total Harmonic Distortion (THD<0.01%, Subwoofer THD<0.2%) , high S/N Ratio (S/N Ratio <-87dB, A-weighting) .
This tone control project can be powered using a power supply that can provide an output voltage from 3 to 8.5 volts .
If you will use a power supply that will provide an output voltage that is in range required by this circuit you can remove 8.2VZD zenner diode from the VDD pin .
This circuit will provide independent tremble and bass control for each channel ( each channel has separate volume and treble , bass control ) .