Pioneer MU-61
¥ 28,500 (around 1972)
¥ 32,500 (around 1973)
Commentary
Belt drive phono motor using DC servo hole motor.
The motor is a brushless motor using a Hall element developed by Pioneer.
The driving magnetic field of the Cono motor is generated by the current from the transistor circuit that works by switching the Hall element. The magnetic force change to the Hall element is sequentially and regularly performed by a pre-magnetized magnet rotor to obtain accurate rotation.
In addition, since it is a low-speed motor that rotates at 10 times the speed of a turntable, vibration is reduced, and S/N and durability are improved.
Equipped with a DC servo mechanism, even if rotation deviation occurs, accurate rotation is maintained by controlling driving voltage.
This servomechanism consists of a capacitor-type rotational frequency detector and an electronic control circuit that are not affected by changes in ambient temperature or by the magnetic force of the rotor magnet. The capacitor-type detector directly changes the rotational frequency deviation into a change in the oscillation frequency, and the electronic control circuit controls the driving voltage according to the change.
A purely electronic system is used for changing the number of revolutions. Unlike the conventional system, there is no need to change the belt, so there is no trouble caused by the belt or its changing mechanism.
In addition, each of 33 1/3 and 45 rpm is equipped with an independent fine adjustment knob, allowing the rotational speed to be adjusted within ± 2%.
Model Rating
Type | Phono motor |
Motor | Brushless DC servo hole motor |
Drive system | Belt drive |
Turntable | 31 cm Diameter Aluminum Alloy Die-cast (1.4 kg) |
Number of revolutions | 33 1/3, 45 rpm, fine adjustment possible |
Rotational speed adjustment range | ± 2% or less, independent adjustment of each speed |
Speed change | Electronic |
Uneven rotation | 0.05% or Less (WRMS) |
S/N | 55 dB or more |
Attachment mechanism | Rotational speed fine adjustment knob Strobe light Level |
Semiconductor used | Transistor : 22 Diode : 15 pcs IC : 1 Hall element : 2 pieces |
External dimensions | Width 317x Height 133x Depth 353 mm |
Weight | 6kg |