Compressor

EE JULY/AUGUST 1987 by S G Dimitriou This versatile circuit serves to raise the average output power of an AF amplifier. Its simplicity makes it suitable for appli- cations in intercom systems, public address and disco- theque equipment, and also in various types of transmitter. Compression of music and speech essentially entails reducing to some extent the dynamic range of the AF input spectrum in order to drive an AF power amplifier with a fairly steady signal level just below the overload margin, thus increasing the average output power of the system. However, some distortion is inevitably incurred in the process of amplifying the relatively quiet input sounds and attenuating the louder sounds. It is evident, therefore, that the control of the amplifier/attenuator function in the compressor determines to a large extent just how much dis- tortion is introduced by the circuit. Before inserting any type of 1 compressor in an AF signal path, due consideration should be given to the...