From left to right: Marconi/Reisz carbon mic,
BBC AXB ribbon, STC 4017 moving coil (dynamic)
I recently had a chance to watch The King’s Speech, winner of this year’s Best Picture Oscar. The film was good and deserved the award. Being involved in the recording business, I could not help but notice the interesting looking microphones that the King spoke into and wondered what kind of mics they were. Most of the mics seen throughout the film were puck-shaped and spring mounted. There was one mic that had a sideways teardrop shape, also spring mounted. I turned to someone who might know about these things - Malcolm Addey.
“The movie itself was very well done except for the accuracy of the mics and broadcast equipment. … All the mics used in the film were mock-ups of carbon mics, spring mounted in rings - a type which had gone out of use long before King George VI came to the throne. In fact, ribbon mics, the BBC-Marconi type AXB, had come into general use by 1935. For outdoor use, the STC 4017 moving coil was the standard during the period the motion picture covered. Either type would have been accurate for the final speech scene”
So the mics you see in the film were carbon mics. The only problem is that they would not have been the mics used by the King.
Malcolm continues, “By the mid 30s the use of carbon mics had been completely discontinued by the BBC. The teardrop (or bomb) shaped mic you mention was, in fact, an early condenser mic manufactured by Western Electric used by the BBC between 1931 and 1935. Condenser mics were largely experimental at the time, proving to be very unreliable and subject to going noisy under even moderately humid conditions.
The following are comments from an email by my friend and colleague Chris Owen, a BBC engineer. We are both historians and collectors of vintage broadcast equipment.”
Malcolm’s colleague’s comment:
“Have now seen the King's Speech. Great film, but so many mistakes on the equipment and microphone front. George V's Christmas Broadcast at the start of the film had the Engineers using OBA/8 (not invented until 1937), The microphones in front of George V were the later ones c1936 that were used for the first time for Edward VIII's broadcast in 1936. The mics BBC stands were all STM/11 or STM2/1 and date from just post WW2. The microphone used for the speech at the end of the film were just SO wrong. There is no way any broadcast would have been done using a carbon mic in 1939. It would have been STC 4017s and two of them. Cue lights were all wrong. They had a 1950's wall cue light (same as on our Gent clocks), but badly mounted on a wooden box. Finally (for now), the Western Electric / STC Bomb condenser microphone was obviously a replica, but the nearest thing to being correct. So sad when they could easily have got it all right.”
There you have it.
Suggested sources for more information:
1) BBC Engineering 1922 - 1972 by Edward Pawley, published in 1972 by BBC Publications. According to Malcolm, the book has become rare and much sought after and is considered to be the bible on the subject.
2) BBC Year Books published annually from 1928 to 1987, e.g. The BBC Year-Book 1934
3) Howard Tremaine's Audio Cyclopedia (USA) is another good source for professional audio information.
Thanks to Malcolm Addey and Chris Owen for the historical information.