A microphone amplifier with compressor and noise gate. The gain is fixed and the compression ratio is set by a single resistor, relative to a fixed rotation point. Signals above this point are limited by the IC to prevent overload. The noise gate's threshold is also fixed, where signals below this value are attenuated. The device is powered from a single voltage supply and suitable applications are for example microphone preamplifiers, sustain effect for music instruments, mixers and computer-, telephone- communication- equipment.