BBC C/3 amplifier. Marked "C6 Line 7". Full BBC number C/3/10. Ex-BBC Bristol, Bristol number J2133.

BBC radio control rooms contained a large number of low frequency amplifiers which served to amplify the various transmissions originating in or passing through. These can be divided into four principal types known respectively as A, B, C, and D amplifiers. The C Amplifier is a single stage amplifier only, and its purpose is to separate the outgoing land-lines from the output of the B Amplifier.