Description This relatively simple mixer was designed for three dynamic microphones, but can be re-designed for more or less. Level and tone controls are available to tailor the sound to your needs. Circuit Diagram Parts Part Total Qty. Description Substitutions R1, R2, R3 3 1K 1/4W Resistor R4, R5, R6 3 10K Logarithmic Pot R7 1 1Meg 1/4W Resistor R8, R10 2 10K 1/4W Resistor R9, R11 2 100K Linear Pot C1, C2, C5, C6 4 0.1uF Ceramic Disc Capacitor C3, C4 2 22nF Ceramic Disc Capacitor U1, U2 2 741 Op Amp J1, J2, J3 3 Input Jacks Of Your Choice MISC 1 Board, Wire, Knobs, IC Sockets Notes Email Anatoly I. Shikhatov with questions, comments, etc. R1-R3 are level controls. R9 and R11 control bass and treble, respectively. Since the circuit draws such low current, two 9V batteries can be used for a power supply. Building the mixer in a metal case will cut down on noise. Source - http://www.aaroncake.net/circuits/mixer2.asp