Modern broadcasters are calling for transistorized amplifiers in their studio installations. The use of transistors has resulted in small, compact amplifier designs, with the added features of lower power consumption, less heating, and greater reliability than with tube-type equipment. Many studio amplifiers have been transistorized. The exception has been the popular automatic Gain Control amplifier. Ever since the introduction of the Unilevel in 1954, the studio compression amplifier has found many applications in radio and television broadcast applications. It has proven to be highly useful in intercom service, as well as its major function of providing automatic control of program channel levels.