YAMAHA PX-1
¥ 480,000 (around 1978)
Commentary
A player system equipped with symmetrical linear arms.
The PX-1 arm feed mechanism is designed to move an arm base with six Delrin bearing rollers over two precisely polished guide rails.
In order to move this arm base stably and smoothly at a speed that matches the pitch of the record, the angle of the arm is detected by a high-precision non-contact photoelectric arm angle detection mechanism, and the signal is sent to an arm drive mechanism using a coreless motor controlled by a servo circuit that suppresses malfunctions caused by the eccentricity of the record.
This arm drive mechanism drives the arm base with low friction using a precision polished drive screw. Since the photoelectric tracking sensor of this arm feed mechanism is non-contact type, no side pressure over the initial motion sensitivity (5 mg) of the arm is applied to the cartridge stylus.
In addition, the drive motor is sealed with rubber to cut off rotational and vibration noise, enclosed in a brass case and fixed with an insulator, and torque is transmitted through a rubber belt to prevent vibration from being transmitted to the drive screw.
The linear tracking arm is a short arm with an effective length of 190 mm. In addition, the inertia mass is reduced by 40% compared to the offset arm by adopting a rectangular and horizontally long balance weight and moving the shell connector closer to the eye point of the arm. Therefore, the equivalent mass at the cartridge stylus point is as small as 16g. In addition, it is a dynamic balance type because it has a symmetrical design and can balance the front and back of the arm.
Since this arm is a linear tracking system, there is no tracking error and no offset angle, there is no inside force. In addition, since it is a symmetrical design, there is a lateral balance. It can be neutral and raced against the recording sound groove. Crosstalk distortion and cross modulation distortion, which adversely affect sound quality, are sufficiently suppressed. Since the balance is left, right, front and back and the equivalent mass is small, excellent tracing ability is shown even for records with sleds.
The main shell is a Yamaha special integrated shell (shell + pipe) made of aluminum die-cast for acoustic use. An attachment pipe for universal shell is also included for cartridge replacement.
The turntable has a dead weight of 5.6 kg and an inertial mass of 760 kg ・ cm, both of which are made from solid ultra-duralumin.220 pole, 15 winding slot-less DC motor with starting torque of 2 kg ・ cm is adopted for the motor to drive this turntable. Furthermore, the spindle, bearing and housing to support the turntable are designed to be as sturdy as possible. Bi-directional servo with electronic brake, quartz PLL direct drive configuration is adopted.
The FG for detecting the number of revolutions is an all-round average push-pull electromagnetic type, and the pitch can be varied by ± 6% by turning OFF the PLL.
The player base is made of aluminum die-cast with a thickness of 5 mm, and the insulator is a large combination of spring and oil damper to reduce external vibration.
In addition, the power supply part, which causes leakage flux and vibration, has a separate structure to prevent adverse effects from the power supply part.
The acrylic cover is 5 mm thick and has a small area and high rigidity structure.
To minimize loss of information, we use a Naglex silver clad low-impedance cable and use oxygen-free copper for lead wires to reduce DC resistance.
Equipped with pure electronic full auto mechanism of auto lead-in, auto cut, Oatley turn, auto repeat. Also, for manual operation, if you turn the arm feed knob with your finger tip, the arm moves smoothly.
Yamaha logic ICs are used for the logic circuit with an LED sequence display that allows operation to be seen at a glance.
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Model Rating
| Type | Full auto player |
| Motor | 20 Pole, 15 Winding Slotless DC Motor |
| Drive system | Direct drive |
| Turntable | 31 cm duralumin shaved, 5.6 kg |
| Wow flutter (WRMS) | Not more than 0.025% |
| Signal-to-noise ratio | 62 dB or more |
| Rotational speed adjustment | + / - 6 per cent |
| Tone arm | Dynamic balance linear tracking arm |
| Weight range of the mounting cartridge | 4g ~ 13g |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Rated power consumption | 27W |
| External dimensions | Body : Width 480x Height 154x Depth 416 mm Power Supply : 124 mm W x 90 mm H x 385 mm D |
| Weight | Body : 27 kg Power Supply : 5 kg |
| Sold Separately | Dedicated Spare Head Shell HS-P1 (¥ 13,000) |