The BBC-Marconi Type A is a

ribbon microphone A ribbon microphone, also known as a ribbon velocity microphone, is a type of microphone that uses a thin aluminum, duraluminum or nanofilm of electrically conductive ribbon placed between the poles of a magnet to produce a voltage by electromag ...

that was produced by the

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...

History

RCA The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Comp ...

Hollywood

Each pair of microphone and

amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost t ...

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

retail price index In the United Kingdom, the Retail Prices Index or Retail Price Index (RPI) is a measure of inflation published monthly by the Office for National Statistics. It measures the change in the cost of a representative sample of retail goods and servic ...

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 Charles de Gaulle's 1940 appeals. In the early 1950s, the BBC began to design the Type A's successor. The first model was the

pressure gradient In atmospheric science, the pressure gradient (typically of air but more generally of any fluid) is a physical quantity that describes in which direction and at what rate the pressure increases the most rapidly around a particular location. The p ...

PGD design. In 1953, production began on the PGS (pressure gradient single) ribbon microphone in agreement with the company

Standard Telephones and Cables Standard Telephones and Cables Ltd (later STC plc) was a British manufacturer of telephone, telegraph, radio, telecommunications, and related equipment. During its history, STC invented and developed several groundbreaking new technologies incl ...

(STC). In the mid-1970s, STC's manufacturing was transferred to

Coles Electroacoustics Coles may refer to: Businesses * Coles Supermarkets, a supermarket chain in Australia * Coles Group, parent company of Coles Supermarkets, Coles Online, Coles Express, Coles Liquor and flybuys *Coles (bookstore), a bookstore chain in Canada, a di ...

, 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 function, periodic force (or a Fourier analysis, Fourier component of it) is equal or close to a natural frequency of the system ...

. 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 decibels. The AXBT weighed approximately . The microphone had a figure-of-eight polar pattern. The aluminium ribbon was less than one

micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

thick.

Footnotes

Sources

* (

Wayback Machine The Wayback Machine is a digital archive of the World Wide Web founded by the Internet Archive, a nonprofit based in San Francisco, California. Created in 1996 and launched to the public in 2001, it allows the user to go "back in time" and see ...

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