A Stereo Tone Arm for Tracking at 2 grams on a Record Changer

Abstract

It has long been recognized that very low tracking forces in phonograph pickups will minimize wear of the record and styli. Another advantage of low tracking force is the reduction in wavelength loss. Two factors tend to place a limit on the minimum tracking force which can be used. One is the mechanical impedance of the pickup and the other is the stability of the pickup-tone arm system when subjected to jarring. Tracking force of approximately 2 grams is usual in high-priced manual players which are handled carefully by relatively skilled people. However, in most home phonographs tracking force is found to be above 6 gms. to insure stability when subjected to vibration. This paper describes a tone arm configuration which was developed to allow tracking at 2 grams in automatic record changers with a low mechanical impedance pickup described in a companion paper. As an additional benefit the new tone arm protects records by preventing damage due to accidental scratching or dropping of the tone arm.