Audio Database

Image of the MU-61
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