Motor and Drive
Power for the turntable platter and the changing mechanism is supplied by a four-pole, split-pole synchronous motor suspended by radially located elastic mounts and having a very small stray magnetic field as well as little vibration.
The speed of the motor is independent of line voltage, temperature or load variations. Speed is dependent on, and proportional to, power line frequency. The motor is adapted to 50 or 60 cycle (Hz) power line frequencies by the correct choice of the motor pulley.
The platter is driven by the idler wheel which is automatically disengaged from the motor pulley when the unit is shut off in order to protect its driving surface.
Platter speeds of 33-1/3 and 45 rpm are selected by raising or lowering the idler wheel to the appropriate step on the motor pulley.
Tonearm
The Dual 1228 has a light, torsionally rigid metal tonearm in a gimbal type suspension. The actual support is provided by four hardened and precision-polished steel points resting in precision ball bearings. Tonearm pivot friction is thus reduced to a minimum.
It therefore guarantees exceptionally good tracking characteristics. The tonearm head is removable. Before setting the correct stylus force for the particular cartridge installed in the tonearm head, the tonearm should be balanced with the stylus force setting dial at the zero position. Coarse balancing is accomplished by sliding the counterweight and using setcrew, after which a fine adjustment is made by turning the weight. The counterweight is proportioned so that cartridges with a weight of from 1 to 12 grams can be balanced. For the absorption of vibration and rapid small shocks, the counterweight is coupled to its threaded shaft through an elastic medium, and braked to prevent unintended rotation. The tonearm head accommodates all cartridges that conform to the internationally standard ½ inch mounting centers, and whose weight does not exceed 10 grams. Stylus force is set by turning apring housing, which is equipped with calibrations and which stresses or relaxes a spiral spring inside it. The scale is calibrated for a range of zero to 5 grams, and permits exact settings every 0,5 gram within that range.
Specifications
Drive: 4-pole synchronous motor
Platter: Non-magnetic
platter Weight: 1,4 kg
Platter Diameter: 270 cm (10,5 inch)
Platter Speeds: 33-1/2 and 45 rpm, automatic tonearm setdown coupled to speed selector
Pitch Control: Adjustment of approx. 1 semi-tone (6%) at both platter speeds
Speed Check: with light stroboscope for platter speed of 33-1/3 and 45 rpm adjustable for 50 or 60 Hz
Wow and Flutter: less than ±0,00 % rated in accordance with DIN 45 507
Signal-to-Noise-Ratio: (in accordance with DIN 45 500)
Better than 58 dB at rumble s/n
Better than 39 dB at rumble unweight ted s/n
Tonearm : Torsion resistant, aluminum tonearm in universal four-point gimbal suspension
Tonearm Bearing Friction
Vertical : < 0,008 p
Horizontal : less than 0,18 p
Pick-up Head (Cartridge Holder): Removable, suitable for acceptance of all cartridges having ½” mounting and a deadweight of 2 – 8 gram (including mounting fixtures)
Stylus Pressure: Continuously-adjustable from 0 – 10 p, reliable as from 0,5 p stylus pressure
Current Type: AC 50 or 60 cycle, with appropriate motor pulleys
Line Voltage: 110/130 V and 220/240 V selector
Power Consumption: less than 10 watt
Current Requirements
approx. 64 mA at 220 V 50 cycle
approx. 115 mA at 110 V 60 cycle
Dimensions (W x H x D): 13" x 5" x 10-3/4"
Weight: 4,3 kg
No comments:
Post a Comment