The BBC-Marconi Type A is a ribbon microphone that was produced by the

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and Marconi between 1934 and 1959. The microphone has been described as "iconic" and a symbol of the BBC.

History

In the early 1930s, the BBC became aware of RCA's model 44 ribbon microphone that was used in

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. Each pair of microphone and

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would have cost the BBC £130 (approximately £6,500 in 2009Based on a retail price index calculatio

/ref>). As this was not within the BBC's budget, they designed their own microphone, the Type A, alongside Marconi. There were initial concerns that the new design Patent infringement, infringed the patent of the RCA microphone, but these were overcome. The Type A was produced at a cost of £9 each (approximately £475 in 2009). The original Type A microphone was designed by engineer F. W. Alexander under the guidance of H. L. Kirke's Research Department at the BBC. In 1940, the Type A was used in the broadcast of

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's 1940 appeals. In the early 1950s, the BBC began to design the Type A's successor. The first model was the pressure gradient PGD design. In 1953, production began on the PGS (pressure gradient single) ribbon microphone in agreement with the company Standard Telephones and Cables (STC). In the mid-1970s, STC's manufacturing was transferred to

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, who continue to manufacture the PGS under the model number 4038.

Technical

Four versions of the microphone were produced – the "A", "AX", "AXB", and "AXBT". The original microphone used a thick aluminium ribbon which produced a harsh

resonance Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...

. This was soon replaced with a thinner ribbon, and was named Type AX. In 1943, the AXB model was launched, which featured balanced wiring. In 1944, the microphone was renamed the AXBT with the addition of a Ticonal magnet to increase sensitivity by 6

decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a po ...

s. The AXBT weighed approximately . The microphone had a

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. The aluminium ribbon was less than one

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thick.

Footnotes

Sources

* (

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cached version of page) * * * * * * * * * * {{refend Microphones Products introduced in 1934 BBC history