SHURE 55SW UNIDYNE VINTAGE CARDIOID DYNAMIC BROADCAST MICROPHONE W/SWIVEL MOUNT
Original connector, XLR adapter cable included
no case or manual
Shure originally made relatively low cost carbon and crystal mikes for use in PA systems and in the communications field as well as phonograph pickup cartridges. The year 1937 was a turning point when a young engineer named Benjamin Baumzweiger (who later changed his name to Bauer) began developing his idea for a unidirectional microphone using a single dynamic element. Prior to this all dynamic mikes were non-directional. RCA and Western Electric had both developed unidirectional pattern mikes using a combination to two different microphone elements in the same housing.
Bauer felt that the best way would be to use just one element, reducing the large and bulky size of the dual element units. He came up with his theory of using a series of front and rear openings in the dynamic element which allowed sound waves to reach both sides of the element's diaphragm. Using acoustic principles that produced a time delay between the sound entering from the rear and sound striking the front of the diaphragm. By varying the amounts of acoustical resistance encountered at the rear openings, Bauer was able to achieve cardioid, supercardioid, or hypercardioid patterns using a single element, and the first true unidirectional dynamic microphone became reality.
Shure called this design the “Unidyne”. The Unidyne model 55 became an instant hit in the audio field. The Unidyne set a new standard of high quality audio pickup combined with discrimination against unwanted sounds. This offered a great new ability to control feedback and reduce ambient noise pickup. The Shure 55 also came in at a much lower price-point than previous directional mikes. Utilizing Shure's proprietary “uniphase” technology, the Unidyne was marketed for PA, recording, and broadcast applications. The streamlined chrome head could be tilted up to 90 degrees. A built-in cable connector and stand mounting were part of the unit.
With the Unidyne Shure was able to crack open the broadcast market against the dominant players RCA and Western Electric. In 1940 Shure introduced a separate broadcast version of the Unidyne which became the model 556 (the 556B is the 200-250 Ohm version) . This unit had closer tolerances and an improved isolation mount of live rubber. An external call letter plate could be purchased separately as an accessory. Many radio stations used the Shure Unidynes in their control rooms and studios.
The original Unidyne is sometimes called the “fat boy”...or the “Elvis mike”...of course many, many famous performers used these mikes long before Elvis came along. In 1952 Shure came out with an updated version of the Unidyne that was quite a bit smaller with a more squarish shape compared to the rounded “fat boy”. This new model was the model 55S...the “S” for small Unidyne. Shure made both the large and small models available for about the first year and then the big model was dropped from the catalog.