Circuit Tree Band Audio Equalizer
This 3 band equalizer
circuit is an active filter network for bass, mid and high audio ranges. It is designed around the LM833 opamp from National Semiconductors.
The output of this 3 way graphic equalizer is designed to be DC coupled, however due to slight DC variations through the 100K potentiometers at the feedback lines of the opamp A2, a coupling capacitor might be needed.
This opamp
IC has the following charactersistics: very low noise figure, wide bandwidth and a relatively high slew rate.