Dual‐Stylus Ceramic Phonograph Pickup Development

The freedom from humidity and temperature limitations have made ferroelectric ceramics a valuable type of transducer for phonograph pick‐ups. Originally designed for 78‐rpm records, two groove sizes now indicate the use of dual styli. A pick‐up structure is described in which dual styli are used back‐to‐back on one lever. A mechanism is provided on the bottom of the pick‐up whereby the stylus assembly can be turned over to present the proper stylus to the record. This structure imposes no dynamical limitations on the performance of the pick‐up, as the additional mass required for the second stylus tip is only a small percentage of the total mass, and no additional stiffness constraints are imposed on the system. Reasonably flat characteristics have been obtained. In one commercial model a sensitivity of over one‐half volt is achieved with a frequency range to over 8000 cps with a tracking force of 6 grams for microgroove and 9 grams for old standard‐groove records.