With graphic equalizer we make selective cutting off or boost, of selected departments of acoustic spectrum. With this way we can adapt the musical reproduction, in the characteristics of space where we hear. This can create however also problems if go to far specifically in the gain of some area, with result the distortion. The circuit should be made in two pieces, one for each channel, the potesometer regulation it should they are Fader. With switch S1 we can by pass the circuit, leaving the musical program, to pass without alteration (FLAT). With the potesometer RV1 we regulate the gain of each channel.