Sony PS 4750 (1974–1978)

At 8.5kg and clad in SBMC, a composite as rigid as it is industrial, it feels less like a turntable and more like a precision instrument bolted into a chassis.

Overview

The Sony PS-4750 is not polished wood and brushed aluminum. It is a utilitarian machine. Released in October 1974 and produced through 1978, this direct-drive player system came out while Sony was pushing to refine and democratize high-fidelity turntable technology. At ¥53,800 (circa 1974), it sat in the middle of the range, below the flagship PS-8750 and the theatrical TTS-8000. Owners report a machine built for function. Its 34 cm SBMC platter is made from a thermosetting resin reinforced with glass fiber and calcium carbonate, which gives it inertia and damping. The entire cabinet uses the same material, which adds to the 8.5kg weight and the resistance to resonance. It was never meant to blend into a living room.

Under the hood, the PS-4750 runs on a DC servo motor with a magne-disk servo system, a technology spun off from Sony's Magnesscale division, developed with the technology of Sony Magnesscale. The system magnetizes 512 waves around the platter's edge, and an 8-tooth multi-gap head reads them to hold speed. Wow and flutter is rated at 0.03% WRMS, which is exceptional for a consumer-grade turntable of its era. Speeds are fixed at 33 1/3 and 45 rpm, each with independent ±4% pitch control, so adjusting one doesn't touch the other. Start-up is brisk. Within half a rotation at 33 1/3 rpm, the platter is at operating speed.

The tonearm is a static-balance S-shaped universal design, 314mm in total length with an effective length of 237mm. Overhang is fixed at 15mm, and the offset angle sits at 21°30'. Tracking error ranges from +2°30' to -1°20', which is acceptable but not elite. This geometry isn't built for audiophile cartridge swaps, but for consistency with the included setup. The arm has a replaceable headshell and takes cartridge weights between 4g and 14g, though one source suggests compatibility up to 16.5g. Needle pressure is adjustable from 0 to 3g, with 2g cited as optimal. A tilt adjustment mechanism lets users align the cartridge so the stylus meets the groove perpendicularly. That is a rare feature at this price point.

The factory-mounted cartridge is a moving magnet (MM) type with a 0.5 mil diamond stylus and 3mV output at 1kHz (5cm/s). Frequency response runs from 10 Hz to 30 kHz, and channel separation is 25dB at 1kHz. These specs are not class-leading. The system wants a 47kΩ to 100kΩ load impedance, standard for MM cartridges of the period. The stylus is replaceable via the ND-134G unit.

Power draw is listed as 5W in the primary source, though a secondary report cites 20W. That discrepancy is unresolved, but the lower figure fits the modest internal component count of 6 transistors, 5 diodes, and 1 IC. The power supply is rated for 100 VAC (50/60Hz), though multivoltage capability is confirmed via a switch under the platter, allowing use in regions beyond Japan. It is big: 477mm wide, 420mm deep, and 175mm high.

Specifications

Manufacturer	Sony
Product type	direct-drive player system
Years of manufacture	10/74 - 1978
Original price	¥ 53,800 (around 1974)
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	5W
External dimensions	Width 477x Height 175x Depth 420 mm
Weight	8.5kg
Turntable	34 cmSMBC, 1.0 kg
Motor	DC servo motor
Drive system	Direct drive
Number of revolutions	33 1/3, 45 rpm
Speed adjustment range	+ / - 4 per cent
Wow flutter	0.03%WRMS
Signal-to-noise ratio	70dB(DIN-B)
Tone arm	Static balance S-shaped universal tone arm
Effective length	237mm
Total Length	314mm
Overhang	15mm
Tracking error angle	+ 2 ° 30', -1 ° 20'
Offset Angle	21 ゜ 30'
Needle pressure adjustment range	0 ~ 3g
Shell Weight	7.5g
Usable cartridge weight	4g ~ 14g
Cartridge tilt adjustment range	± 12 °
Cartridge	MM Type
Frequency characteristic	10 Hz to 30 kHz
Separation	25dB(1kHz)
Output voltage	3 mv (1 khz, 5cm/s)
Optimum load impedance	47k Ω ~ 100k Ω
Compliance	10x10 -6 Cm / dyne (vertical, horizontal)
Needle pressure (optimum needle pressure)	2g
Needle	0.5 mil diamond needle
Weight	5.5g
Exchange needle	ND-134G
Semiconductor used	IC : 1 Transistor : 6 Diode : 5 pcs

Key Features

34 cm SBMC Platter with Magne-Disk Servo System

The speed stability comes from the magne-disk servo system, a descendant of Sony's industrial Magnesscale technology. A 34 cm platter made of SBMC (Sony Bulk Mould Compound) carries a magnetized ring of 512 waves around its edge. An 8-tooth multi-gap head reads this signal, averages out fluctuations, and feeds real-time correction to the DC servo motor. This closed-loop control is what gives the low 0.03% WRMS wow and flutter. Unlike the quartz-locked systems that came later, it uses no crystal oscillator. The magnetic encoding sits directly on the platter. Owners note its reliability when maintained. The platter also has air-filled dampers, small rubber cushions that isolate it from motor vibrations.

Independent ±4% Pitch Control per Speed

Many turntables of the era had a single pitch control affecting both speeds. The PS-4750 has independent adjustment for 33 1/3 and 45 rpm, which helps DJs or audiophiles who switch speeds often and want precise calibration for each. The ±4% range is generous, enough for musical transposition or for matching broadcast standards. The control is manual, with no digital readout, so alignment requires a strobe. The PS-4750 has a built-in stroboscopic speed checker, though its exact placement (horizontal, according to one source) isn't detailed in the primary spec sheet.

Static-Balance S-Shaped Tone Arm with Tilt Adjustment

The tonearm is pragmatic. Its S-shape reduces mass while keeping rigidity, and the static-balance system avoids the complexity of dynamic counterweights. The 237mm effective length and 15mm overhang suggest a geometry optimized for the included cartridge rather than universal compatibility. The standout is the ±12° cartridge tilt adjustment, which lets users align the stylus vertically relative to the record surface and minimize tracing error. The arm also has an overhang checker built into the chassis.

MM Cartridge with 0.5 mil Diamond Stylus

The factory cartridge is a moving magnet type with a 0.5 mil diamond stylus. Output is 3mV, compatible with most standard MM phono stages. The 10 Hz - 30 kHz frequency response exceeds typical vinyl bandwidth, suggesting Sony tuned for headroom rather than literal extension. Channel separation of 25dB at 1kHz is adequate, though not exceptional. Some competing cartridges of the era achieved 30dB or more.

SBMC Cabinet and Platter Construction

SBMC (Sony Bulk Mould Compound) is a thermosetting resin reinforced with glass fiber and calcium carbonate. It offers high rigidity and internal damping. It is used for both the platter and cabinet, and it resists resonance far better than die-cast aluminum or plastic. Its density adds to the unit's 8.5kg weight, which helps isolate the turntable from external vibrations. The look is industrial, grayish and slightly textured. Some find it cold, others like its no-nonsense durability.

Historical Context

The PS-4750 entered the market as Sony's third-tier turntable, below the professional PS-8750 and the high-end TTS-8000. A 1975 US advertisement contrasted it with the 1966 TTS-3000, positioning the 4750 as the evolution of Sony's perfectionist engineering. It lacked the sonic pedigree of its siblings, but offered a good balance of technology and price. WEGA also rebadged it as the P-4410, finished in all-black. By 1976-1977, it was displaced in the lineup by the PS-4300, which was itself quickly superseded by the first of Sony's "X" series, the PS-X7, a shift toward more automated, consumer-friendly designs.

Collectibility & Value

Current market examples range from €99 to around $200. It is not a rare find, but well-preserved units with original cartridges and dust covers command premiums. One known issue is capacitor C106, which can fail and affect the strobe function. Repair is straightforward with a service manual available. A recurring warning among owners: do not oil the motor. The sealed DC servo unit is designed to run dry, and lubrication can attract dust and degrade performance.