The following was excerpted from the 1946 Astatic Catalogue.
The D-104, Astatic's first Crystal Microphone manufactured in 1933
Away back in 1930, two radio amateurs, C. M. Chorpening, W8WR (now W8MJM), and F. H. Woodworth, W8AHW, both of Youngstown Ohio, began searching for a better microphone for their phone transmitters. Up until this time they had been using various carbon type microphones. The condenser type appealed to them as an answer to their problem. Several units were designed and given trials on the air. Before long, other amateurs among their acquaintance began visiting their shacks, interested in either building or buying this new type of "mike." Chorpening and Woodworth, encouraged by this interest, decided to form a partnership and build these units for their friends. While the condenser unit proved reasonably satisfactory, it had certain limitations which it was hoped could eventually be overcome
It was about this time that an old acquaintance, Mr. Charles E. Semple of Cleveland, who had been visiting his "ham" friends frequently, invited them to pay him a visit. With a background of phonograph and loud speaker experience, Mr. Semple was then occupying bench space in the Brush Laboratories, experimenting with elements made from Rochelle Salts, (Sodium Potassium Tartrate). Through Mr. Semple, the two visitors met A. L. Williams, electrical and mechanical engineer, and Dr. C. B Sawyer, scientist, who demonstrated the action of these new elements in relation to microphones, phonograph pickups, speakers, recording heads, earphones and other devices where it was desired to transform mechanical energy into electrical energy or the reverse. Here, it seemed, they had found the answer to a simple, low-cost, dependable "mike" for the "ham rig."
By 1933, CHorpening and Woodworth found it advisable to incorporate a manufacturing and sales company and to branch out with a line of Crystal Microphones, Crystal Phonograph Pickups and Recording heads for manufacturers and Radio Jobbers. Mr. Semple was brought into the new organization as designer and later served as general manager until his death in 1939.