Yamaha P-750 Record Player / Turntable Working Japan

The P-750's rotation system was a direct-drive DC 4-phase 8-pole coreless Hall motor, controlled by a quartz PLL servo.

The DC 4-phase 8-pole coreless Hall motor, due to its structure, had no cogging and rotated smoothly. Because it was a non-contact type using Hall elements, it also produced low mechanical and electrical noise. The quartz PLL servo controlling this motor detected the turntable's rotation speed using a full-circumference integrating FG (frequency generator) and compared its phase with a signal from a high-precision crystal oscillator. Combined with a 30cm diameter, 1.6kg weight, and 210kg・cm² inertia mass (including rubber sheet) turntable, this achieved highly accurate rotation with a wow and flutter of 0.015% (WRMS, FG direct reading) and an S/N ratio of 77dB (DIN-B).

The tonearm featured the newly developed ARS (Anti-Resonance Straight) arm. The ARS arm was a nearly symmetrical straight arm with a large, horizontally elongated rectangular balance weight positioned close to the pivot point, thereby suppressing vibration. Furthermore, the span (distance) between the pivots supporting the arm was more than double the usual distance, and the angular contact bearings (bearings that simultaneously receive forces in both the axial and circumferential directions) were supported by rubber dampers, resulting in improved sensitivity and elimination of resonance caused by play. In addition, to counteract deflection vibrations at the front and rear of the arm pipe, the pipe holder was made large and robust, and the 30mm section from the pivot point was made into a double structure, suppressing the occurrence of various resonances.