This simple electronic circuit is an excellent preamplifier for low impedance dynamic microphones.
The circuit is based on the low noise NE5534 operational amplifier. It works better if microphone’s impedance is less than 200 ohm. The gain is about 50db and the common-mode rejection ratio (CMRR) is better than 70db. This value for the CMRR is achieved only if you use low tolerance resistors (equal or less than 1%).
Using symmetrical power supply of about ±15V, the supply current is about 8mA.
