Audio Database

The

Pioneer PLC-1700
80,000yen(around the 1973 time)

Description
 
The arm-less player which adopted the brushless DC servo direct-drive hall motor.

The direct-drive phone motor adapting a hall device is adopted as a motor.
Instead of the brush which was indispensable to the conventional DC motor, Pioneer has applied the hole blocking which developed the process to the magnetic-field detection of a switching organization. The oscillation decreased compared with the DC motor which has a mechanical switching organization by this, and S/N and the endurance are improved.
33 [ and ] as the rotational frequency of a record with the same rotation of a motor itself the direct-drive which drives a turntable directly at 1/3.45rpm -- since a scheme, the middle deceleration mechanism leading to rotation unevenness did not exist at all, but has acquired the outstanding property.

A hall device is a kind of a semiconductor, is the crossbar thin film metals made from the N type Insb composition, and if it sends an electric current through two terminations and an attraction of magnet is applied to a quadrature, it will have changed the magnetism into the electricity using the "hall effect" which a voltage produces among other two terminations.
In Pioneer, the new process of a vacuum deposition method was developed, and till then, 30-50micro have improved the thinness which was a threshold to the thinness of 0.8micro, and has realized the cheap and small hall device.

In order to always control a rotation correctly, DC servo mechanism is carried.
The rotation is automatically controlled by the capacitor type oscillator which does not receive the influence by a transition of ambient temperature, and the attraction of magnet of a rotor magnet, and this control circuit maintains the stable rotational frequency.

The brake mechanism who stops a turntable at the moment is carried at the same time it turns OFF a power switch.

The pure electronic formula is adopted as a switching of a rotational frequency. Moreover, a fine tune of a velocity is possible, looking at the stroboscope minced by the perimeter of the turntable by ±4% of within the limits.
The blinking switchpoint is provided in the lamp which illuminates a stroboscope so that it can erase, when unnecessary.

The cabinet of the double structure which combined plywood with thickness of 30mm and the metal base is adopted as a cabinet. Kibe is rosewood native wood finish.

The large-sized thing is adopted as an insulator and the howling and the extraneous vibration are reduced.
Moreover, while a height can adjust freely and looks at the level of a panel, a coordination of the degree of level is possible.

It can be used being able to attach a favorite tone arm to an attached panel. Moreover, if a book jacket is removed, it can be used to 16 type arm.
This board serves as a desorption type which can be removed simply on six screws, and if an optional sub panel is used, it can exchange many kinds of arms easily.

Cut
The Servo
Brake
Insulator
Hall
Phone

Rating of a mode
Form Arm-less player
Motor Brushless DC servo hall motor (18 very 36 slots)
Drive system Direct-drive
Turntable The product made from diameter aluminum alloy die-casting of 31cm (1.4kg)
Rotational frequency 33 1 / 3 or 45rpm
Rotational frequency adjustable range ±4%, an each rotational frequency independent coordination
Rotational frequency switching Electronic formula
Rotation unevenness 0.04% or less
S/N 60dB or more
The arm which can be attached 14 types, 16 type (a hood mounting is impossible)
An attached organization Rotational frequency fine-tune thumb
Stroboscope
Level
Outage brake
Large-sized insulator
The semiconductor used Transistor: 23 pieces
Diode: 15 pieces
IC: One piece
Hall device: Two pieces
Dimensions Width 570x height 187x depth of 434mm
Weight 15.6kg
Option Sub panel PP-307 (1,500yen)