Technics SP-25
¥ 60,000 (around 1979)
Commentary
Direct-drive turntable adopting quartz synthesizer system.
Equipped with continuously variable pitch control function within ± 6% range.
This function is realized by newly developed IC, and it is possible to control any pitch with high precision of quartz. Moreover, the pitch control switch is 0 point and gives a light click feeling.
The drive section uses a unique integrated structure D. D. motor in which the rotor of the motor is integrated with the turntable.
This motor achieves a starting torque of 1.5 kg ・ cm and rotates the turntable at a constant speed in 0.7 seconds. The inertia mass of the turntable is 250 kg ・ cm.2Combined with a high torque motor, it achieves a load fluctuation of 0% within 1 kg ・ cm.
An all-around detection FG that can obtain highly accurate signals is used to detect the number of revolutions, and a quartz oscillator that pursues permanent accuracy is used for the reference signal for controlling the number of revolutions.
An aluminum die-cast turntable with a diameter of 33.9 cm is used for the turntable.
This turntable has a 3-layer deadening structure. The back surface and the outer periphery of the back surface are deadened with special viscoelastic material. In addition, the rubber sheet on the top surface of the table is inserted into the turntable, thereby eliminating adverse effects of resonance and external vibration of the turntable.
The cabinet is made of aluminum die-cast in the same way as the turntable, and the internal cavity is reduced to prevent resonance. From a total perspective, the concept of no vibration and no resonance is thoroughly implemented.
Equipped with an electronic brake.
Model Rating
| Type | Quartz Synthesizer D. D. Turntable |
| Drive system | Direct drive |
| Drive motor | Brushless DC motor |
| Control system | Quartz phase locked control |
| Turntable | 33.9 cm Aluminum Die-cast, 1.85 kg (Including Rubber Sheet) |
| Moment of inertia | 250 kg / cm2(Including Rubber Sheet) |
| Number of revolutions | 33 1/3, 45 rpm |
| Fine tuning of rotational speed | + / - 6 per cent |
| Starting torque | 1.5 kg / cm |
| Start-up characteristic | Constant speed at 0.7 seconds (at 33 1/3rpm) |
| Brake mechanism | Electronic brake |
| Load variation | 0% (Up to 1.0 kg / cm, up to 200g needle pressure) |
| Rotational speed deviation | ± 0.002% or Less (33 1/3 at 45 rpm) 0.01% WRMS (Rotating Part Only) |
| Wow flutter | 0.025%WRMS(JIS C5521) ± 0.035% peak (IEC98A, weighted) |
| SN ratio (rumble) | 78dB(IEC98A weighted) 56dB(IEC98A unweighted) |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 10W |
| External dimensions | Width 349x Height 86x Depth 372 mm |
| Weight | 4.8kg |