The device below is built as an active stereo-tone/volume control for TV receivers, car radios and mains-fed equipment. The device below has function for bass and treble control, volume control with built-in contour (can be switched off) and balance.

TDA1524A Voltage Controlled Tone and Volume Control circuit schematic

We can control all these function using dc voltages or by single linear potentiometers. This device has 4 features. The features are few external components necessary, low noise due to internal gain, bass emphasis can be increased by a double-pole low-pass filter, and wide power supply voltage range. [Circuit’s schematic diagram source: nxp.com]