DENON DP-3000
¥ 43,000 (released in June 1972)
Commentary
A direct drive turntable that inherits the performance and design of the DP 5000 and pursues cost performance.
In the DP 3000, the pulse recorded inside the rim of the turntable is first detected by a magnetic head for speed detection. The pulse signal is amplified and passed through a limiter circuit. A demodulation circuit converts the change in speed into a change in voltage. This voltage is compared with a reference voltage set in advance to achieve the specified speed. The voltage difference is used to control the motor drive power supply voltage for servo control.
As a result, the speed can be easily changed by changing the reference voltage. The circuit and elements used are highly stable, and highly reliable characteristics can be obtained even with temperature change, aging change, negative variable and simultaneously.
In speed detection, the inside of the rim of the turntable is coated with a magnetic material with a large coercive force. Using a special method, pulses of a fixed wavelength are recorded with high precision and high density. This is detected by a magnetic head mounted at intervals of approximately 1/10mm.
In this method, the wavelength error of recorded pulses is suppressed to less than 0.01%, and the frequency of detected pulses is approximately 550 Hz at 33 1/3rpm because pulses are recorded at 1000 locations around the turntable.
This frequency is more than five times that of other methods, making it possible to greatly reduce the time constant of the integration circuit in the frequency-voltage conversion circuit.
The turntable has a weight of 1.1 kg and an inertial mass of 160 kg ・ cm.2Lightweight turntables have been adopted to speed up the start-up time, reduce the load on the bearing, and obtain long-term stable performance.
Speed can be adjusted within ± 3%.
Uses a solid rotor type torque motor.
Model Rating
Type | Turntable |
Drive system | Servo-operated direct drive |
Motor | Solid rotor type torque motor |
Speed control | Servo by frequency detection |
Number of revolutions | 33 1/3, 45 rpm |
Speed switching mechanism | Electrical switching |
Startup time | 1.8 seconds (1/2 rotation, 33 1/3rpm) |
Wow and flutter | 0.03% wrms or less (according to test records) |
Motorboard | Aluminum die cast |
Signal-to-noise ratio | 60 dB or more |
Turntable | 30 cm aluminum die-cast, 1.1 kg |
Moment of inertia | 160 kg / cm2 |
Rotational speed adjustment range | + / - 3% |
Pwer | 100 VAC, 50Hz/60Hz |
External dimensions | Width 370x Height 139x Depth 374 mm |
Weight | 6.7kg |