SONY PS-3750
¥ 47,800 (around 1976)
Commentary
A record player equipped with a slotless magnetic circuit motor and a magnedisk servo.
In order to reduce torque unevenness caused by cogging (changes in magnetic attraction force and mechanical torque) that occurs in DC motors, we have adopted a brush-and-slotless motor with a structure that does not have slots in principle.
This motor consists of a concentric circular solid core, a trapezoidal wave magnetized magnet ring, and a saturable inductor. Since the rotational force generated by the motor is proportional to the amount of magnetic flux passing through the coil and the amount of current flowing, if the amount of current is constant, the rotational force is proportional to the amount of magnetic flux. Therefore, the amount of magnetic flux must be uniform in order to suppress torque unevenness during rotation.
The slotless motor uses a trapezoidal wave magnetizing method for the magnet ring to obtain uniform magnetic flux density.
In addition, in order to detect the relative positional relationship between the stator coil and rotor magnetic pole, a magnetic window is provided in the magnet ring, and an electronic control system that senses magnetism with a saturable inductor is adopted. Stable rotational force is obtained by effectively using a constant magnetic flux.
In order to obtain more accurate rotational speed, a unique magne-disk servo system is adopted for the servo circuit.
This system is a high-precision speed control function that introduced Sony Magne-scale precision measuring equipment technology that measures things in the micron unit or less. The outer circumference of the turntable that can be taken in a wide range is coated with barium ferrite with high coercive force. Around this circumference, 512 speed detection signal is magnetized with high density. The signal is detected at an average value with an 8-tooth double-gap head, and high-precision and stable servo detection is realized.
In addition, since the generated signal frequency is as high as approximately 284 Hz at 33 1/3rpm, the servo compensation frequency band can be widened, and the slight delay and advance during rotation can be accurately captured, and quick response characteristics can be obtained.
The cabinet uses SBMC, an acoustic material with high internal loss and low resonance.
In order to take full advantage of the features of SBMC, thickness and structure were comprehensively examined, and resonance parts were eliminated by integral molding with reinforcement at important points to realize a frame structure resistant to resonance.
In addition, a large, height-adjustable insulator is integrated with the cabinet and attached to lower the center of gravity to increase the stability of the cabinet.
Uses XL-15, which is a MM type cartridge.
The XL-15 is composed of a conical damper that suppresses unnecessary vibration caused by friction between the sound groove of the record board and the needle tip, a resin containing carbon fiber in the pole piece block, and a magnetic circuit with excellent left and right balance.
The tone arm uses a high-sensitivity static balance type, and the bearing uses a precision pivot bearing to increase the sensitivity. In addition, each joint including the pivot is supported by a damper to provide anti-vibration design.
The head shell is made of aluminum light alloy and is lightweight, highly rigid and non-resonant.
And, it is equipped with inside for scan seller and lateral balancer.
A stroboscopic illumination prism is mounted on the peripheral strobe, making it easy to see the stroboscopic pattern.
33 equipped with independent pitch control for 2 speeds of 33 1/3 and 45 rpm.
A remote oil dump type arm lifter is adopted.
Uses a rotatable arm rest for easy needle pressure adjustment.
Uses a low-capacity phono cord.
Equipped with 2 replacement shell stands.
Comes with a removable acrylic dust cover.
Model Rating
| Type | Direct drive player system |
| <Turntable portion> | |
| Turntable | 31.4 cm Aluminum Die Cast |
| Motor | Brush and slotless motor |
| Servo system | Magnedisk servo |
| Drive system | Direct drive |
| Number of revolutions | 33 1/3, 45 rpm |
| Speed adjustment range | + / - 4 per cent |
| Start-up characteristic | Within 1/2 Rotation (33 1/3rpm) |
| Wow flutter | 0.03%WRMS |
| Signal-to-noise ratio | 70dB(DIN-B) |
| Tone Arm Section | |
| Tone arm | Static balance type |
| Effective length | 216.5mm |
| Total Length | 300mm |
| Tracking error angle | + 3 °, -1 ° |
| Needle pressure adjustment range | 0g ~ 3g |
| Weight of attached shell | 7.5g(SH-135) |
| Usable cartridge dead weight | 4g ~ 13g When using auxiliary weight : ~ 22g |
| Cartridge Section | |
| Cartridge | MM Type Cartridge XL-15 |
| Frequency characteristic | 10 Hz to 30 kHz |
| Separation | 25 dB or More (1 kHz) |
| Output voltage | 4 mv (1 khz, 5cm/s) |
| Load impedance | 50k Ω ~ 100k Ω |
| Compliance | 15x10-6cm/dyne |
| Needle pressure (optimum needle pressure) | 1.2g ~ 2.5g (1.7g) |
| Needle | 0.6 mil diamond needle |
| Dead weight | 5.2g |
| Exchange needle | ND-15G(¥5,500) |
| <General> | |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Power consumption | 7W |
| External dimensions | Width 445x Height 150x Depth 365 mm |
| Weight | 8.9kg |
| Attachment | Auxiliary weight Tracking error confirmation gauge 45 Rotation Adapter Cartridge spacer |