Dynamic Mic Preamp Circuit Diagram. Use stabled and regulated power supply. The following diagram is the circuit diagram of tube mic pre amplifier 12ax7.
This circuit has in built gain control. This circuit is little hard to built. Use stabled and regulated power supply.
If you use 200ω microphones r4 must be 220ω and c1 is 4 7uf.
The c1 in this circuit is the same capacitor c described in the electret microphone circuit above and its role is to cut off the dc offset of the input signal such that we work out only the ac component of the input signal. The circuit is very simple contains only few components and can be assembled in few minutes if all parts are available. Diagram bellow shows the pin numbers in brackers for the second identical channel. You must have an intermediate or advanced skills to build this circuit.
