RCA 4-AA-1 Condenser Microphone

RCA 4-AA-1 Announce type condenser microphone (including capsule & amplifier), Ser No.1225(T), c. 1928. With UZ-4083-A condenser capsule, response 30 to 10.000 Hz, built-in DC coupled amplifier type AA-4088 with 70, 250 & 500 ohms output impedance. The suitable condenser microphone control panel was the type 11-A. Bristol number J2004. Possibly used at the BBC's Savoy Hill studio. There is a record of a single studio there being equipped with a condenser microphone in 1928. This microphone predates the Western Electric/STC ‘bomb’ condenser microphones used by the BBC in the early 1930s at Broadcasting House.