Home > Circuits > Op-Amp Tone Control
Modified:21:22, 22 October 2013
CIRCUIT DESCRIPTION
This tone control is a little better than the transistor version in that it has better separation between the bass and treble controls and a better boost and cut range.

I haven't built this and tested it but on simulation it performs really well.

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Simulation 1:
100Hz 1V RMS sine

Blue: Input signal

Red: Output signal

Output with full bass cut.Output with full bass boost

Simulation 2:
5KHz 1V RMS sine

Blue: Input signal

Red: Output signal

Output with full treble cut.Output with full treble boost

CIRCUIT DIAGRAMS

This is the basic circuit. It runs from a split supply of +/-12 to +/-15 volts. It will function at lower voltages but you will have to reduce the input level to prevent distortion from clipping.

An input signal around 500mV should be about the safe limit to give some room for the uneven recording level of many mp3s.

The op-amp used in the simulation was a general purpose 741 type but better quality performance may be gained by choosing a higher quality op-amp specifically for audio applications.

Below is a version for a single supply which should be a minimum of 12volts and preferably 18 to 24v for high input signals. In this case a V/2 reference is created by the potential divider R6,7 and decoupling capacitors added at the input and output.

SPLIT SUPPLY VERSION

SINGLE SUPPLY VERSION

Written by Phil Townshend 2008
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