Dynamic Mic Preamplifier Circuit

Posted on Feb 5, 2014

This mic preamp uses the low noise IC uA739. The circuit is an example of how a good preamplifier can be designed for dynamic microphones. The IC houses two identical integrated preamp circuits. The second preamp is used in identical manner for the second channel of the stereo microphone. The non-inverting input is biased at about 50% of the power

Dynamic Mic Preamplifier Circuit
Click here to download the full size of the above Circuit.

supply. This bias voltage is set by the voltage divider circuit R1 and R4. The point between R1 and R4 is used commonly for both channels. The unwanted HF signals coming from the microphone are filtered out by the RC-circuit composed of R3/C4. Frequency compensation is done by the R7/C6 circuit. The values of R7 and C6 were designed to avoid oscillation at the amplification level of 100. The input impedance is about 47K. This means that a normal dynamic microphone gets connected to a high impedance preamp which in turn produces good results. The output impedance is about several hundred ohms. THe maximum peak-peak output voltage is about several volts lower than the supplied power. The frequency range is from 20Hz to 20KHz (-3dB). The upper cutoff frequency is 80KHz when the low-pass filter is removed from the circuit. The IC shown can be replaced with TBA231 or SN76131 without changind the external circuit.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Portable Mic Preamplifier
    Pedalboard Power Supply
    ray dialer
    Simple 6V charger battery circuit Schematic Diagram
    arduino freertos fan rpm video
    Transistor regulator circuit can adjustable output voltage
    Build an Experimenters Power Supply
    Audio Clipping Indicator
    Gas Discharge Lamps Ballasts and Fixtures
    Circuit power audio amplifier TDA2040 20 watts integrate circuit with pcb and power supply circuit
    32kHz clock oscillator circuit
    T-121 temperature sensors form a temperature control circuit diagram
    Light control principle circuit rooster crows
    Wireless microphone circuit diagram consisting of transistors 9018