Description:
A Western Electric model 630-A microphone, known as an "8 Ball" for its spherical housing. It is a moving coil-type microphone, introduced in 1931.
The pickup side of the device has perforations and a three-pronged mounting housing to which is attached a woven wire accoustic screen or baffle. According to the technical manual, the screen is designed to produce a slight loss in sound, and to reflect sound coming from behind the microphone back to the diaphragm inside the microphone.
The bottom side of the ball has a circular well, with a three-prong electrical connection inside, and stamped, "Western Electric USA / 630-A 3547" around the edge of the well. The bottom also has a small tubular metal bracket mounted on one side.
The bottom side of the ball is marked, "630-A; 3547," indicating that it is a Model 630-A Non-Directional Dynamic Microphone, designed to respond to sound coming from any direction.