The U.S. entered World War Two in December 1941. The following Shure advertisement debuted in 1942. Of particular interest is this sentence from the ad – “Because of the unique processes, seven working days are necessary to complete a single microphone cartridge.”
Our Unidyne Model 55, introduced in 1939, was the first microphone to have a unidirectional cardioid using only a single moving coil dynamic element. The ad illustration shows a simplification of how the patented Uniphase Acoustical Network provided unidirectionality. The Unidyne was widely deployed by Allied Forces, from War Bond rallies to the Manhattan Project at Los Alamos to the signing of the peace treaty with Japan aboard the USS Missouri. As we have learned to expect, Shure products were present, capturing historic moments.
Related information: Timeline and History of the Unidyne Microphone
Arcana – mysterious or specialized knowledge
During the 1940s, our catalog descriptions of the Unidyne Model 55 and its variations never mention the color of the grille cloth. As the product photos were black and white, the color could not be discerned from these images. The World Wide Web, font of all truth and wisdom, spouts conflicting opinions about the “factory-original cloth color.” However, our archive collection revealed the cloth color was mercurial.
Color depended upon what silk-like material was available at a local fabric shop. Shure engineers would bring an acoustic impedance meter to the shop, measure the impedance of suitable fabrics in stock, find a fabric with the desired impedance, and then purchase a bolt or two for use in manufacturing. When the material was depleted, back went the engineers to the fabric shop.
The approved grille fabric colors were black, blue, red, maroon, and white. White discolored quickly in the presence of tobacco smoke and was soon eliminated as an approved color. The aforementioned acoustic impedance meter, custom fabricated by Shure in the 1940s, is held in our archive.
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Acoustic impedance is the resistance offered by a material to air passing through it. For example, loose-woven burlap has a lower acoustic impedance than tight-woven silk, i.e., it is easier to blow air through burlap than through silk.
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The Museum of Modern Art, New York City, website hosts an inventory page for our Unidyne microphone. Its catalog number is 93.2015, i.e., the 93rd object added to the museum collection in 2015.
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WBBM News Radio in Chicago recently aired a story about Shure Incorporated. Click here.
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“The Sabines at Riverbank” is now available online. The book traces the origins of architectural acoustics through the work of Wallace Sabine and the continuation of his legacy at Riverbank Acoustical Laboratories, Batavia, Illinois. The book opens at a pivotal moment in scientific history — when the new field of acoustics began to take shape and the first laboratory dedicated to acoustical testing was established. Highly recommended.
