The circuit of graphic equalizer, allocates ten adjusting potesometer , that each one from them affects in a predetermined area of frequencies, the central frequency of which abstains a octave (double), from the central frequencies of her neighbouring regions. Each unit has common materials with remainder and it differs only in the capacity of capacitors that constitutes the filter in each unit. When the runner of fader regulation RV1 until RV10, is in the middle then we do not have no intervention of filter above in the signal that passes from in his and gain of particular unit, is one [ X1 ]. On the contrary if the runner is moved to a side of exit, the unit acts as filter of cutting off of area and it degrades the signals of predetermined area of frequencies. On the contrary if it is moved to the side of entry, the rung acts as filter of passage of area, strengthening the signals of predetermined area of frequencies. The quality of all materials should be very good. Specifically potesometer RV1... the 10 and capacitors. If it is intended for stereo use then it will be supposed it is made in two pieces with as much as possible suited the materials, between the channels, so that do not exist differences in the regulation of each band frequencies. Switch S1 isolates the circuit EQ, when him we did not need and it ensures level [ flat ] response in the exit of circuit. The circuit should be connected between preamplifier and in a final power amplifier.
circuit from http://users.otenet.gr/~athsam/EQ_10_band.htm