Sony ps-x700 (1981)
A full-auto turntable system with microprocessor-controlled tone arm and quartz-locked motor
Overview
The Sony PS-X700 is a quartz lock direct drive full-auto player system released in 1981. It was designed as a high-precision turntable with advanced electronic control systems for both the tone arm and motor. The unit features a biotracer tone arm, which uses a microcomputer to make rapid logical decisions for precise movement and positioning. It supports 12-inch records with automatic size detection and includes safety features to prevent damage when no record is present.
Specifications
| Product type | Quartz Lock D. D. Full Auto Player System |
| Production year | 1981 |
| Original price | ¥ 99,800 |
| Wow and flutter | 0.015% WRMS |
| Signal-to-noise ratio | 78dB (DIN-B) |
| Tone arm | Biotracer (electronically controlled) |
| Effective length | 235mm |
| Total length | 315mm |
| Needle pressure adjustment range | 0.5g ~ 3.0g |
| Weight of attached shell | 7.7g (SH-156) |
| Usable cartridge weight range (including shell) | 9.7g ~ 16.7g |
| Usable cartridge weight range with auxiliary weight | 15.7g ~ 28.7g |
| Turntable | 32 cm Aluminum Die Cast |
| External dimensions | Width 480x Height 165x Depth 420 mm |
| Weight | 12.5kg |
| Start-up characteristic | Within 1/2 Rotation (at 33 1/3rpm) |
| Load characteristic | 0% (Needle Pressure 150g) |
Design
The PS-X700 features a microcomputer-controlled biotracer tone arm that uses speed and position sensors with a linear motor for fully electronic operation. The arm performs hundreds of logical decisions per millisecond and enables functions like auto lead-in, lead-out, and muting. Its J-shaped aluminum alloy arm pipe offers about eight times the rigidity of conventional designs. The turntable uses a 3-stage rotating system: a linear BSL motor, magne-disk speed detection, and quartz lock for stable speed control. An electromagnetic brake ensures immediate speed stabilization when switching between 33 and 45 rpm. The tone arm’s needle pressure is adjusted electronically via a front-panel control and displayed digitally. A contactless opto-electronic disc size selector automatically detects record size and prevents the arm from dropping if no record is present. The cabinet uses SBMC acoustic material, and vibration-damping insulators filled with high-viscosity elastic material help isolate the turntable from external shocks.
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