Sony ps-x70 (1978-1981)

Name: Sony ps-x70
Brand: Sony

A full-auto direct drive turntable from Sony’s original PS-X series, engineered with precision quartz control and a high-inertia die-cast platter.

Overview

The Sony PS-X70 is a full-auto direct drive turntable produced from 1978 to 1981, marking the debut of Sony's PS-X series alongside the PS-X50. It became one of Sony's best-selling turntables, with tens of thousands manufactured. Designed as a high-end consumer model, it features advanced engineering for its time, including a DC servo-controlled linear BSL (slotless) motor, crystal lock phase control, and a dedicated logic circuit for function sequencing. The turntable was originally priced at ¥79,800 in 1978 and is recognized in Sony's brand history as a "Legendary Product."

Specifications

Production years	1978 to 1981
Product type	full-auto direct drive turntable
Manufacturer	Sony
Original price	¥ 79,800 (1978)
Wow and flutter	0.025% WRMS
Signal-to-noise ratio	75dB (DIN B)
Speeds	33 and 45 rpm
Speed accuracy	±0.002%
Speed control range	±10%
Turntable	32 cm aluminum die-cast platter
Turntable weight	2.2 kg (including mat)
Moment of inertia	340 kg/cm²
Motor Type	DC servo controlled linear BSL (slotless) motor with Magnedisc velocity detection
Start-up characteristic	1/4 turn or less to full speed
Drift time	0.0003% / h or less
Tone Arm Effective length	235mm
Tone Arm Total Length	330mm
Overhang	14 mm
Arm Height Adjustment Range	± 3 mm
Needle pressure adjustment range	0 to 2.5g (0.1g interval)
Anti-skating range	0 to 2.5g
Shell dead weight	11.0g (SH-155)
Usable cartridge weight limit (including shell weight)	11.0 ~ 19.5g
Usable cartridge weight limit (with auxiliary weight)	19.0g ~ 27.5g
Tonearm balance	static balance
Cable capacitance	45pF/m
External dimensions	480 x 165 x 420 mm
Weight	13 kg

Design

The PS-X70 uses a DC servo-controlled linear BSL (slotless) motor to eliminate torque unevenness, paired with a Magne-disk velocity detection system generating 512 wave signals for precise speed control. It features a crystal lock (X-tal lock) phase control circuit and a quartz drive strobe light for accurate calibration. The tonearm, designated PUA-7, is a simplified version of the PUA-9, constructed with a J-shaped carbon-charged aluminum alloy arm pipe and a hardened cemented carbide pivot shaft (5 mm diameter) with a mirror finish. Bearings use a Longs pan design with a single straight shaft. The cabinet is made from SBMC (Sheet Bulk Molding Compound), and the base includes viscous-filled, height-adjustable insulator feet. The headshell connector uses a 4-clamp locking nut with wedge effect, and internal wiring employs Litz wire with urethane coating. Additional features include logic IC-controlled operation, electromagnetic quick-stop braking, audio muting, tonearm safety clutch, viscous damped cueing, direct-read anti-skating and counterweight, feather-touch controls, and a removable spring-loaded dust cover. Record-end detection uses a luminous sensor that applies no lateral pressure to the stylus.

Context

The PS-X70 was one of the original models in Sony’s PS-X series and became one of the company’s best-selling turntables, earning a place among its "Legendary Products." It exemplifies Japanese engineering at its best, with careful attention to materials, textures, and functional design. The PUA-7 tonearm is capable of handling high-quality moving-coil cartridges, reflecting Sony’s intent to position the PS-X70 as a serious audiophile turntable despite its automated features.