Electro-Voice Model 664

"Variable-D"

Following the development of the Shure Unidyne directional microphone, Shure Incorporated developed the "Variable-D" single moving coil element for the Electro-Voice manufacturing company. This new element allowed for low handling noise with excellent directional response.

At right is the Electro-Voice Model 664 microphone, which used the new "Variable-D" element. This microphone was introduced in the mid 1950s, and was designed for the typical sound reinforcement applications of the era.

Astatic WR40

The newly invented crystal, or piezoelectric, microphones had the advantage of a relatively high-output signal. These were intended for low-cost paging systems, and did not have high quality sound recording capabilities. These microphones used a crystal element which was eventually replaced by small, high-energy magnet materials.

These microphones became relatively rare after their replacement by more efficient, cheaper elements, rendering vintage crystal microphones relatively rare. Despite this, Mr. Steele's collection contains three crystal microphones. One of these, the Shure SM5B, is shown at left.