to integrated circuit fabrication thereby minimizing addition of passive circuit components such as resistors and capacitors provision of subtraction circuit 301 in combination with bandpass filter 300 provides a band elimination filter which permits a relatively low q bandpass filter 300 the processed audio signal is then routed to programmable tone control filters 103 tone control filters 103 generally comprise a treble high pass filter a bass low filter and bandpass filters for the mid pass and mid treble frequencies tone control filters 103 also receive programmed input from microprocessor 108 on buses comprising the tone control data latch serial data input and serial clock input tone control filters 103 are conventional active filters such as for example national semiconductor lmc 835 trademark integrated circuits and the like fig4 illustrates the frequency response characteristics of the notch filter fig5 illustrates the low pass frequency response characteristics of the bass filter at maximum boost fig6 depicts the bandpass frequency characteristics of the mid bass filter at maximum boost fig7 illustrates the bandpass frequency characteristics of the mid treble filter at maximum boost while fig8 shows the high pass frequency response characteristics of the treble filter at maximum boost as shown in fig2 the processed audio signal is finally routed to output amplifier 80 then to power amplifier 95 and loudspeaker 96 in operation each microphone channel m1 m8 is individually equalized by programming the various notch and tone control filters to eliminate undesirable feedback frequencies and uniformly shape the frequency response of each microphone channel programming is accomplished by microprocessor 108 and user controls 30 and user display 40 the state of the filters can be optimally adjusted by visual reference to user display 40 and rotary adjustment of 34.