Audio Database

DP-31F
Commentary

This is a microcomputer operated full auto player that has introduced DENON technology in various places.

A direct drive system is adopted for the turntable part.
The drive motor is equipped with a newly developed linear drive MF (Magne-Float) motor. It uses the attractive force between the rotor magnet and the stator yoke to reduce the load applied to the pivot by the weight of the turntable and rotor. This structure is effective in reducing uneven rotation, prevents wear of the pivot, and maintains smooth rotation performance.

The servo circuit employs a bi-directional servo DENON quartz system that combines a high-precision magnetic recording detection system and a quartz lock system. The high-precision magnetic recording detection system uses a magnetic head to detect 1,000 pulse signals recorded at an accurate pitch inside the rim, which is almost the outermost peripheral position of the turntable, and controls them while comparing them with a reference voltage. It has high detection accuracy, high-speed response, and speed detection at the outer circumference where wow flutter appears most often.
In addition, both forward and reverse servos provide a severe response to slight increases and decreases in rotational speed, improving static dynamic load characteristics.

The tone arm uses a straight-type arm with a lighter weight.
This is to bring out the performance of the high-compliance cartridge. Even when the attached cartridge or other high-performance high-compliance type is used, the low-band cutoff frequency is set to around 12 Hz, so that the ultra-low-band noise caused by the warping of the record can be eliminated.

The DP-31F is equipped with a damper structure to reduce the resonance of the arm itself, and adopts a newly developed tone arm float system to actively block the vibration of the arm.
In this system, four spring plates are attached to the cabinet, and an arm is attached to this plate. The vibration modes of the cabinet, plate and arm base are different, and since the plate operates only in the vertical direction, the arm floats from the cabinet, effectively suppressing howling, etc.

The cartridge is equipped with DL-60, a high compliance light weight MM cartridge.
In pursuit of high musical expressive power, this cartridge uses a precise vibration system to realize the ability of flat reproduction up to 30 kHz or higher with a needle pressure of 1.8g. It also uses an elliptical needle to reduce tracing distortion in the high-frequency range.

The tone arm drive system of the full-auto mechanism uses a unique contactless system to eliminate factors that cause sound quality degradation and to realize excellent operability.
The DP-31F has a configuration in which the arm is operated by two precision dedicated angular control motors for horizontal operation and lifter operation. The operation of the arm is commanded by the microcomputer. Therefore, during both horizontal operation and lifter operation of the arm, the arm is in a free state as in manual machines, and the arm is not mechanically restrained even when the auto mechanism is in operation. Therefore, good arm sensitivity and usability are achieved.
In addition, with the adoption of an electronic servo lifter, the arm moves up and down at a constant speed. It is not affected by the needle pressure or ambient temperature, ensuring smooth operation and minimizing impact between the needle tip and the record.

The operation part adopts a front operation type with push buttons, and a quick repeat system is adopted in addition to the usual autoplay, Oatley turn and autostop.
In the click-repeat method, the tone arm does not return to the arm rest during repeated performances, but returns directly to the lead part of the record, allowing for speedy operation.
In addition, when the power is switched from OFF to ON with the hands down on the record, the music is played continuously as it is, making it possible to smoothly start recording for copying records to cassettes.

Uses an electronic brake.
It works when the tone arm starts to return to the armrest, and when it returns to the armrest, the turntable is in a stopped state.

Equipped with an electronic anti-skating mechanism.
With a non-contact structure that cancels the inside force by controlling the torque of the angular control motor for arm drive, an appropriate amount of cancellation can always be obtained, and sensitivity does not decrease due to mechanical friction.

Uses LED to display constant speed rotation. This LED also displays power ON.

It uses an integrally molded cabinet made of special hard resin.

Integrated mold dust cover is adopted.

Uses a low-capacity output cord.

Uses a turntable sheet with excellent anti-vibration effect.

Model Rating
Type Full auto player
Phono Motor Section
Drive system Bidirectional servo direct drive
Motor Linear drive MF motor
Speed control Speed servo and phase servo by frequency detection
Number of revolutions 33 1/3, 45 rpm
Wow and flutter 0.012 (0.02)% w. rms (rotating system)
0.02%W.rms(JIS)
Rotational speed deviation 0.002% or less
Signal-to-noise ratio 78 dB or more (DIN-B)
Startup time Within 2 Seconds (33 1/3)
Load characteristic 0% (Needle Pressure 80g Outer Circumference)
Voltage characteristic 0% for 90 ~ 110 V
Turntable Aluminum Die-cast 30.8 cm
Arm Section
Type Static balance with damping, shell exchange type, light mass straight type
Effective length 220mm
Overhang 16mm
Tracking error 3 degrees or less
Needle pressure variable range 1 Rotation 2.5g (1 Scale 0.1g)
Applicable Cartridge Dead Weight Approximately 4.5 ~ 9g
Shell PCL-30 (Special Hard Resin Dedicated Type) : Approximately 3.3g
Output code Low Capacity Output Cord Approx. 1.2m
<Cartridge>
Type MM Type
Model Name DL-60
Output voltage 2.5mV
Left-right separation 25 dB or More (1 kHz)
Playback frequency 20 Hz to 30 kHz
Needle tip Diamond Elliptical Needle (0.3x0.7 mil)
Needle pressure 1.8 ± 0.3g
Compliance 10x10-6cm/dyne
Dead weight 4.6g
Needle exchange DSN-60:¥5,000
<General>
Cabinet Special rigid resin integral molding
Pwer 100 VAC, 50Hz/60Hz
Power consumption 6W
External dimensions Width 424x Height 130x Depth 388 mm (With Dust Cover Closed)
Weight Approx. 6 kg