The Crystal Phonograph Cartridge
The attached article from "Successful Servicing" magazine August 1953 explains the operation of the Crystal phono cartridge that was popular at the time. The article explores the finer points of Rochelle salt Crystal storage and maintenance. The author explains the sensitivity of the crystal to excessive humidity and excessive dryness and temperature. Excessive dryness destroys the crystal.
The Rochelle salt crystal was inexpensive and gave very large output signals. I measured 40Vp-p at the output of the crystal cartridge in my Sonora TE-38 while playing a 78rpm record. A comparable ceramic cartridge will give must lower output voltage, but it does not require operation and storage in a restricted range of humidity and temperature.