MICROPHONE OF THE MONTH MARCH 2025

Sometimes it is best to be honest if you make a mistake, so I have to excuse myself, I was mistaken when I wrote about the Shure 737 'Monoplex', in January 2018, as "the only crystal microphone with a directive recording pattern".
In fact the 737 was preceded by the 'Uniplex', Shure's model 730 crystal microphone, which was introduced as early as January 1939.
Under the attractive streamlined casing was a unique invention: a 'Uniphase' crystal element.

Shure technician Benjamin Baumzweiger (he later changed his name into Ben Bauer), had been working on research, since 1937, to produce a directive pick up pattern, with a single capsule. If this Holy Grail was found, it would become possible to produce a low cost directional microphone, which would elevate Shure to become the most important microphone maker of the US.

Bauer designed a crystal pick up, in which an acoustical network allowed sound to reach not just the front of the diaphragm, but also the rear.

In theory, if sound waves reach both sides of a diaphragm, the result is zero movement of the diaphragm, thus no sound. But because the sound waves coming from the front travelled a longer distance, because of the acoustic network, only sounds coming from the rear were nulled.

For frequencies up to 2500 Hz, sensitivity for sounds coming from the rear, was reduced by as much as 15 dB; it was practically 'dead' at the back. Because the capsule was less sensitive for the higher frequencies anyway, the new crystal element had good directivity across its complete audio range of 30 to 10.000 Hz.

The 'Uniplex' was born and it became a big success, for use on stage and in loud or reverberant places it was uniquely suited. Since it did not pick up much of the ambient noise, the sound of the Uniplex was much cleaner than that of other low or medium priced microphones.

After this, it did not take Bauer long to use the same Uniphase principle for a dynamic capsule as well, and because of the better sound quality of dynamic, compared to crystal microphones, the Shure 'Unidyne' 55 dynamic became an even greater success.

The 55 Unidyne was Shure's first dynamic microphone, it became an icon, and almost everyone is familiair with its fantastic shape.

Shure proudly advertised both the Uniplex and the Unidyne as the microphones that ended the problem of feedback, with its horrible squeak.
All modern dynamics are based on the same principle, so when you enjoy their sound today, remember, you have Ben Bauer to thank for it.

The 730 Uniplex was made until 1947 and was used by many entertainers, like Billie Holyday, who was often photographed with it. There are stil some 730s around, although most of the crystal elements have not survived.

The back of the casing is very open, to allow sound waves to reach the back, but the construction is very fragile and can become very brittle. Nonetheless their shape is highly appreciated and they are sought after by collectors, that long to own such a piece of history.

These and many more types feature in my book Witnesses of Words. More information about that can be found at www.witnessesofwords.com