The Protech Audio Model 589 is a high quality audio controlled switch coupled with a professional quality preamplifier. The unit is designed for applications requiring switch closures to follow the presence of an audio signal. The unit is capable of functioning in a wide variety of installations. A typical application would be the turning on of bypass relays in paging systems during priority announcement. Multiple units may be used to design a multi-level priority system. The switch-selectable remote threshold capability allows this unit to serve well in systems requiring different threshold levels at different times of the day. The built-in preamplifier is a very cost effective feature, eliminating the need for separate microphone or line level preamplifiers. The Model 589 features two different types of closures, CMOS and Relay. The relay closures areconfigured in two Form C contact arrangements. The CMOS closures are arranged in two Form A contacts. The relay closures are capable of switching high current loads. The CMOS is recommended for lower level audio (microphone level) switching, since they introduce no switching noise.