MICROPHONE OF THE MONTH JANUARY 2016

The first microphone I would like to point the attention to in the new year is a very old carbon microphone. Until now I have not spent any attention, in this section, on microphones, based on this principle of operation, which is really an omission because in Europe these were the first professional microphones. They were all based on the Reisz microphone, which was developed by Georg Neumann in 1923; a hollowed out marble block, which contains carbon granules and electrodes, sealed of by a thin rubber membrane. In the United States this type of microphone was not used, but the 'double-button' variety instead: two metal plates separated by carbon granules, the thin front plate was the membrane in this design.

Philips produced the model 4210 around 1927, in the Netherlands: a round shape of porcelain, filled with carbon granules containing two electrodes and enclosed by a thin membrane. The pictured 4245 does have a marble block as housing; a luxurious version of the 4210, which equalled the Reisz quality and was usable for Radio.

In Germany, the 4210 was sold as Rectron MH 8, seen here in the lower picture, it was made for the German Navy and its full name was Rectron MH 8 Marine (possible extra durable for use at sea). Rectron was a ghost company founded by Philips to circumvent patents for electron tubes by Telefunken. Apparently, it worked so well that the Reisz patents could be "borrowed" for creating microphones as well.

Carbon microphones had a high noise floor, dynamic microphones would replace them more and more from 1932, because of their better sound quality and smaller size, but Philips continued to make them for a long time and used them for their sound reinforcement systems.

Even after World War II, Philips put these microphones to use, during the Olympic Games of 1948, in London. The company also did the sound reinforcement in the later editions, in Helsinki (1952) and Rome (1960), but used more modern dynamic models for those.

This is one of the types that feature in my book Witnesses of Words, which was recently released. More information about that can be found at www.witnessesofwords.com