Optical Compressor

A type of audio compressor that uses an electro optical attenuator to control the dynamics of the processed signal. An electro optical attenuator basically consists of a light source whose intensity is proportional to the level of the input signal, and a photoconductive cell whose resistance decreases as the light intensity presented to it increases. This photoconductive cell controls the volume of the amplifier that attenuates the volume of the output signal. Thus when a louder signal is input, the light shines brighter, the photocell’s resistance goes down, and the amplifier reduces its gain, producing the effect of audio compression – for each dB that the input signal exceeds the threshold, the output rises by something less than a dB depending upon how the ratio is set and the exact properties of the photo cell circuit being used.