Mic Pre-Amp with Clipping

Signal clipping is usually avoided in most application, but we can find some useful examples where clipping is intentionally employed in audio processing. One example is signal limiter in SSB or radio transmission.  In radio communication, the source of modulating signal (the audio)  affect the modulation depth and should be limited to prevent cross talking the adjacent channel if the audio signal level is too high. A smooth clipper using diode is used to limit the signal gracefully.  Such circuit is shown in the schematic diagram below, Q1 and Q2 are HEP-54 diodes are 1N456 or HEP-158.