This is a good pre-amplifier for microphones that can be. Used in, for example, mixing consoles The circuit operates with a dual op-amp type NE 5532. The amplifier must be adjusted. Simply plug the power and control over P1 such that half the supply voltage (6 V) on pin 3 of IC1 state. P2 is then adjusted to the desired volume.     R1 = 8,2 kW  R2, R4, R5, R6 = 10 kW  R3 = 1 k  P1 = 4.7 K?  P2 = 100 k  C1, C2, C4, C6 = 10 uF  C3 = 470 nF  C5 = 100 nF  IC1 NE = 5532      
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