Vocoder speech input faceplate

Here is the speech input module for my Vocoder project. It consists of a microphone preamp, a line input, tone control, two level indicators and a limiter. The amplification of the microphone preamp is adjustable with one resistor (R8), to fit your needs. A level indicator is added to prevent overdrive and achieve a good SNR for your input signal. The line input and the microphone signal are mixed together with OpAmp IC6A. The amplification of the following OpAmp IC6B is determined by R39 and the variable resistance of the VTL5C3. The limiter stage is optional, you can leave it out with no problems. If used, adjust the values to your needs.

Vocoder speech input: schematic microphone preamp

This stages are followed by the tone control. You can adjust bass, middle and treble over a wide range. The output buffer drives the signal for the analyzer module. The signal level here is indicated by a level indicator.

Vocoder speech input: line in, limiter and tone control

Vocoder speech input: PCB stuffed

Vocoder speech input: module inside