A high quality microphone preamplifier using a single power supply, suitable for dynamic or electret microphones. The opamp used can be any low noise, high performance type, e.g. NE5534,TL071, OPA 371 etc.
The design is a standard non-inverting design, the input is applied to the non-inverting input of the op-amp which is pin 3 in most cases. The input impedance is 23.5k, the overall voltage gain is determined by R2 and R1according to the following formula: Vo = ( R2 / R1) + 1
Operational amplifiers feature high gain bandwidth products, have a fast slewing rate and have extremely low noise. It is difficult to acheive the same performance using discrete components. Finally the overall signal to noise ratio has been calculated, the source was a 1k impedance microphone generating a 1mV pk-pk sine wave.
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