They were introduced to compete with disc sound recordings from companies such as Victor Talking Machine company. Unlike competitors’ discs, Edison Discs used up and down movement rather than side to side (or lateral) and so the grooves have smooth sides and variable depth. Because of this, Edison Discs are incompatible with other phonograph discs (although some adaptors were available).
Edison’s 10-inch discs played for nearly five minutes per side with 150 threads per inch (TPI), and revolved at 80 RPM. They were also ¼-inch thick and were filled with wood flour, or later, china clay.
Sales peaked in 1920, and in 1926 a microgroove version (450 TPI, allowing up to 40 minues per side on a 12 inch disc) was introduced but technical problems meant it was not a success.
Sales continued to drop, and the last Edison Discs were made in 1929.
A later Edison dictation system, the Voicewriter, re-used the name ‘Edison Diamond Disc’ from the 1940s for the unrelated recording medium.
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Preservation / Migration