ONKYO PX-100M
¥ 500,000 (released in 1981)
Commentary
A high-grade linear motor system with drastically improved rotational bare characteristics, aiming at the ideal phono motor.
The PX-100M uses an induction type linear motor that drives the turntable directly around its outer circumference. This motor realizes excellent rotational accuracy. In addition, from the principle of operation as an induction type motor, the rotor has no magnetic pole, and there is no cocking phenomenon associated with the pushing and pulling of the magnetic pole in the movement of the rotor, and ideal smooth rotational characteristics are ensured by the continuous thrust given from the stator.
The PX-100M has excellent bare characteristics and does not require a servo circuit. However, since the PX-100M has some slight variable elements such as temperature characteristics of lubricating oil between shaft and bearing, the minimum necessary servo is applied.
The principle of linear motor rotation is that when a current is applied to a coil, a magnetic field is generated, and eddy currents are generated in the conductor in the magnetic field. When this magnetic field is moved in the rotational direction, the magnetic flux that cuts the overcurrent changes, so the disk is guided in the direction of the magnetic field. To move this magnetic field, a sine wave with a 90 ° phase difference is added. In fact, to increase efficiency, many poles with a 90 ° phase difference are superimposed. In addition, to increase the torque of the linear motor, the stator and rotor are opposed to each other in the center so that the magnetic flux acts effectively.
In the case of the PX-100M, by arranging the stator 4 blocks facing the rotor symmetrically about the shaft center, torque unevenness is completely cancelled, and smooth rotation is realized.
The turntable has a dead weight of 10 kg and an inertial mass of 2000 kg ・ cm.2Moreover, it adopts a heavy class turntable made of pure copper machined, and an extremely thick and highly rigid stainless steel shaft with a shaft diameter of 20 mm and length of 94 mm.
By molding pure copper, which has good electrical conductivity and is ideal for linear motor rotors, by machining it, it can be made compact because it has a specific gravity of 8.9. By machining it out of pure copper, the turntable and rotor can be finished in one piece because it is machined out of pure copper. Moreover, the accuracy of the rotor sandwiched between coils can be secured. In addition, dead-end material is attached to the back of the turntable to suppress the rumbling of the turntable.
In addition, a tungaloy ball with higher hardness than any other metal is used at the lower end of the shaft, and ethylene resin is used for the thrust seat. The space between the shaft and ball is filled with special oil for heavy loads to improve abrasion resistance and S/N.
A high-torque DC motor that operates only at start-up and a drive circuit are installed in order to quickly obtain constant speed rotation.
In order to obtain high rigidity, the cabinet is subjected to precision processing by milling after forming an integrated aluminum casting.
In addition, Al-Zn damping alloy is used as the material of the arm base, which is inserted into the cabinet and tightened.
The turntable sheet is made of transparent amorphous polyolefin by center injection molding and has an excellent uniform thickness accuracy. This eliminates unwanted resonance caused by deterioration of the physical properties and adhesion of the turntable surface.
Comes with an acrylic dust cover.
The arm base for the long arm was sold separately.
Model Rating
| Type | Linear motor system |
| Motor | Main motor : Outer rotor DD induction type linear motor Auxiliary Motor : High Torque DC Motor |
| Turntable | Tough Pitch Pure Copper Block Machined, Maximum Diameter 33 cm Dead weight : 10 kg, inertial mass : 2000 kg ・ cm2 |
| Control system | Quartz PLL control |
| Wow and flutter | 0.005% |
| Number of revolutions | 33 1/3, 45, 78 rpm |
| S/N | 78 dB or More (DIN-B, Measurement Limit) |
| Start-up characteristic | Specified rotation at 1/2 lap (with starting booster) |
| Braking system | Plunger driven mechanical type |
| Applicable Arm Effective Length | Body Arm Base : 229 ~ 283 mm When using separately sold arm base : 235 ~ 312 mm |
| Power consumption | 55W |
| External dimensions | Width 560x Height 206x Depth 374 mm (Including Dust Cover) |
| Weight | 40kg |
| Sold Separately | Arm Base for Long Arm AB-100 (¥ 62,000) |