This is an audio amplifier designed for use in theatre and cinema sound amplification systems. Although it is unknown where this particular amplifier was initially used, it dates from the late 1920s. It would have been one of the first amplifiers to be used by cinemas and theatres to present amplified sound with film. It would have been used in a system employing the disk type of media (synchronised and non-synchronised) and later used with the optical sound track technology.
From the late 1920s through the 1930s, movie sound and audio circuit design was at the forefront of the electronics industry. The Western Electric amplifiers were designed by the Western Electric Company, the manufacturing and research and development arm of AT&T (the Bell Telephone System). Their experience in developing electronics for telephone systems enabled Western Electric to establish and maintain a leading role in the development and introduction of sound to cinema.
Nearly eighty years later, elements and nuances of Western Electric audio amplifier design from the 1920s and 30s continue to be rediscovered and resurrected by audio circuit designers and incorporated into product designs in the High Fidelity (HiFi) industry (USA, Japan & Italy).
Campbell Bickerstaff, 2007