Altec 639B Microphone

Altec 639B Microphone-Front View

Altec 639B Side View

Western Electric introduced the model 639B microphone in 1940.  In the late 1930's, WE's audio business was spun off to became Altec.  Other than the name, the Altec and WE 639B's are identical. 

This is an elaborate, studio-quality unit which included both moving-coil dynamic and ribbon velocity elements.  A six-position screwdriver actuated switch allowed the two elements to be used separately or in concert to produce a variety of directional patterns.  It is also quite large, as microphones go, measuring about 5.5" high, 3.5" wide, and 4.5" deep.  It was used extensively in radio broadcasting and in recording work throughout the 1940's and 50's.

Altec 639B Diagram