Audio Database

The

DENON DP-5000
68,000yen(December, 1971 release)

Description
 
It is the direct-drive turntable which inherited the engine performance and design of DP-5000, and also investigated cost performance.

In DP-5000, the pulse currently recorded inside the rim of a turntable by the magnetic head for speed detection is detected first, the pulse signal is amplified, and change of speed is changed into change of voltage for a limiting circuit circuit by through and a recovery circuit. And the reference voltage set so that it might become this voltage and the speed of beforehand regulation is compared, the drive power supply voltage of a motor is controlled on the voltage of that difference, and the servo is performed.
Thereby, a speed change can be easily performed by switching a reference voltage. Moreover, the circuit and element which are used have very high stability, and the characteristic that reliability is high is realized also to a temperature change, a variation per hour, and negative variable simultaneity.

Speed detection performs magnetic coating with a big material of anti-magnetism inside the rim of a turntable, and is carrying out high-density record of the pulse of a fixed wavelength in high accuracy by the special method. This is detected by the magnetic head for detection which was able to be attached at intervals of about 1 / 10mm.
With this method, since it is stopped to only 0.01% or less and 2000 pulses are recorded on all the turntable circumferences, the wavelength error of a record pulse is 33. As for the frequency of the pulse detected at the time of the speed of 1/3rpm, about 1100Hz is obtained.
This frequency can make small sharply the damping time constant of the integration circuit located in those with 10 or more times, and a frequency-voltage conversion circuit as compared with other methods.

While having adopted the lightweight turntable of weight [ of 1.1kg ], and inertial mass 160 kg-cm2 as a turntable and making starting time it early, the burden of the bearing was eased and the engine performance stabilized over the long time has been obtained.

±6% of speed regulation is possible for a speed fine regulation selection button in the variable state.

The very smooth solid rotor type 2 phase torque motor of the revolving magnetic field was made the motor, it takes it, and the run bull is reduced by using exclusive amplifier for the drive.

Block
Control Frame
Detailed Turntable

Rating of a mode
Form Turntable
Drive system Servo type direct drive
Motor Solid rotor type 2 phase torque motor
Speed control The servo by frequency detection
Number of rotations 33 1 / 3 or 45rpm
Speed change mechanism Electric change
Starting time 1.2 seconds (1/3 rotation, 33 1 / 3rpm)
Wow and flutter Below 0.025%wrms (based on a test record)
Motor board Aluminum die-casting
Signal to noise ratio 60dB or more
Turntable 30cm aluminum die-casting, 1.1kg
Moment of inertia 160kg-cm2
Number-of-rotations adjustable range At the time of Variable: ±6%
Power source AC100V, 50Hz/60Hz
Dimensions Width 370x height 139x depth of 374mm
Weight 6.8kg