BBC GPA/1A General Purpose Amplifier. With variable gain giving up to 80dB into 600 Ohms. 2 valves. Ex-BBC Bristol. Full BBC number is GPA/1A/736. Bristol number is J2230.

War conditions made it necessary to reduce very considerably the number of different types of amplifier used by the BBC. Experience showed that the principle of a general purpose amplifier had many advantages over the pre-war system and the GPA/1 was designed to retain these advantages and at the same time to remove the deficiencies inherent in the earlier amplifier (D/11) which resulted from austerity restrictions at the time of its design. The amplifier is rack-mounted and takes its supplies from a standard mains unit, such as the MU/16.