The Orban/Parasound Reverberation system represents a significant advance in increasing the performance/cost ratio of artificial reverberation generators. New concepts in driving electronics for the Hammond spring delay line have resulted in the solution of problems typical to even the highest priced units using this delay system. The O/P Reverb is available in four models to meet a variety of customer requirements. MODEL 105A comes mounted behind a 1.5 x 9" panel, and is designed to be mounted in mixing consoles using standard modular strips. It has no internal power supply, and requires + 15 volts of well-filtered DC at approximately 100 ma. MODEL 105B is identical to model 105A except that an internal power supply is provided, and the unit is powered by the 110/220 volt AC line. MODEL 105C is a 1 3/4" rack mounted version of the system. It is self-powered from 110/220 volts AC. There is a provision for the addition of a remote hard limiting indicator lamp which can be mounted so that it can be easily seen by the mixer. MODEL 105D consists of two model 105C's, mounted on a single 1 3/4" rack panel. The economy of the O/P reverberation system makes multiple echo channels economically feasible for many smaller studios. The 105D provides maximum space economy. All versions are supplied with a plug-in 4-spring delay line assembly, which is mounted separately from the electronics.