of constants of each block 2-1 R3, R4 (R11, R12) The gain of amp1 depends on R3, R4. Gain of amp 1 = R3/R4 times. The gain of amp1 must not exceed 4 times (12 dB). R3 + R4 6 100 kΩ (C4 = 4.7 µF). 2-2 C2, C3 (C5, C6) C3 is for coupling amp 1 with amp 2 and its value is 1 µF. C2 is for controlling the.