Without Which...

...No Broadcasting Would Be Possible

This old microphone is displayed in the rear lift lobby of Old Broadcasting House. The original "Type A" version of it was created by the BBC in 1934 after seeing something similar, made by RCA in 1931, being demonstrated in Hollywood. But the RCA mics cost £130 each, the equivalent today of over £5,000, so the BBC - risking patent infringement - designed its own version, specially manufactured by Marconi at £9 each, which is around £360 in today's money. After a couple of modifications, the model in my blipfoto - the AXTB - came into use in 1944, weighing in at a hefty 9lbs 3oz. The microphone worked by having a very thin ribbon of aluminium foil in a very strong magnetic field. Sound waves hitting the ribbon caused it to vibrate in sympathy. These vibrations disturbed the magnetic field thus generating a small but continuously oscillating voltage which could then be amplified and routed through a sound mixing desk to either transmitter or recording machine. The BBC finally stopped using this particular type of microphone in 1959.