SONY PS-X75
¥ 89,800 (released in 1979)
Commentary
A full-auto player equipped with a contactless full-auto mechanism based on the electronic control arm "Biotracer".
The biotracer is equipped with a speed sensor, a position sensor and a linear motor in the vertical and horizontal directions of the arm, respectively. The signals detected by the two sensors are sent to a servo amplifier, which supplies the necessary current to the linear motor and controls the movement of the arm. The speed sensor works to smooth the movement of the arm and simultaneously improve the acoustic characteristics such as resonance and inside force. The position sensor works in conjunction with a 128 word x4-bit microcomputer to operate the arm such as full auto operation, needle pressure adjustment and inside force cancellation. It usually makes several hundred logical judgments for each operation, checks the arm position, speed and status of each operation switch, and processes commands at a speed of less than 1/1000 second.
This biotracer suppresses the peak of the low-resonant frequency fo to less than 3 dB and improves crosstalk. It is also resistant to record warping, has improved wow and flutter, and is resistant to shock and howling.
The tone arm can be moved left and right, the turntable can be operated independently for strict queuing, and the needle pressure can be adjusted by the knob on the front panel for fine-tuning the needle pressure during performance.
Since it is a contactless system, smooth and quiet operation is realized.
In addition, it has a built-in muting mechanism linked with the arm lifter to prevent shock noise when the record meets the needle tip.
Equipped with a record size selector that automatically selects the record size. In addition, if you press the start button without setting a record, the needle will return without dropping.
In addition, the inside force cancel force corresponding to the needle pressure is automatically activated.
It uses a simple linear BSL (slotless) motor that does not require a brush or slot. It eliminates the slot that causes cogging, so it achieves quiet and smooth rotation with less uneven torque.
In addition, high torque can be obtained due to high efficiency, and reliability and durability are also excellent.
The Magne-disk speed detection method is used to detect the speed of the servo circuit.
In this system, the multi-gap head detects the mean value of the detection signal that is magnetized at high density on the turntable, making it possible to catch even minute changes in the rotational speed. In addition, since the generated signal has a high frequency of approximately 284 Hz at 33 1/3rpm, servo compensation is possible up to relatively high frequencies of the flutter components.
It is equipped with a crystal lock so that the temperature characteristic of the element can ignore the effect on the detection signal.
By controlling the phase using the high oscillation precision of quartz crystal, stable circuit characteristics are obtained without being affected by changes in ambient temperature and power supply voltage and frequency.
By strengthening the joint of each connection part of the tone arm and promoting integration as much as possible, resonance elimination is attempted.
First, the neck cylinder mechanism, which is the joint of the head shell and tone arm, has a structure in which the tip of the shell plug is held by strong force due to the wedge effect and the root of the shell plug is tightened firmly from four directions.
In addition, the arm pipe is made of a special aluminum alloy and has a J-shaped structure with a high bending strength, giving it approximately eight times the rigidity of conventional aluminum pipes. In addition, this pipe has an integrated structure from the neck cylinder to the bearing.
In order to prevent movement of the operating point of the arm by looseness caused by the clearance for rotating the ball bearing in the bearing section, we have adopted a structure in which the arm is supported by a straight shaft with a long distance between the fulcrums. This minimizes movement of the operating point even in the case of slight looseness of the bearing section.
The SBMC sound material is used in the cabinet, and the partial resonance is reduced by examining all aspects such as thickness and structure, and by providing reinforcement in important parts.
In addition, vibration is reduced by making the dust cover thick.
A gel-like dump material is enclosed in the insulator to reduce the adverse effect of vibration.
Model Rating
| Type | Crystal Lock D. D. Full Auto Player System |
| <Turntable portion> | |
| Turntable | 32 cm Aluminum Die Cast |
| Wow and flutter | 0.015% wrms (rotating system) |
| Load characteristic | 0% (Needle Pressure 150g) |
| Start-up characteristic | 1/2 turn or less |
| Drift time | 0.0003% / h or less |
| Signal-to-noise ratio | 78dB(DIN-B) |
| Tone Arm Section | |
| Effective length | 235mm |
| Total Length | 330mm |
| Arm Height Adjustment Range | + / - 3 mm |
| Needle pressure adjustment range | 0 ~ 2.5g (Electronic) |
| Shell dead weight | 11.0g(SH-155) |
| Usable cartridge weight limit (including shell weight) |
12.0g ~ 19.0g 19.0g ~ 26.0g (Auxiliary Weight Used) |
| <General> | |
| External dimensions | Width 480x Height 165x Depth 420 mm |
| Weight | Approx. 13 kg |
| Attachment | 45 Rotation Adapter Auxiliary weight Head Shell (SH-155) Set of cartridge mounting screws |