The Dual CS721,
single-play direct-drive turntable with fully automatic start and stop, plus
continuous repeat.
The new Dual CS721
is the ultimate expression of the principles that determine the performance of
tonearms and drive systems. Its stright line tubular tonearm pivots
horizontally and vertically within a true, four-point gimbal, thus maintaining
dynamic balance in all planes.
Another Dual
innovation - Vertical Tonearm Control - contributes in yet another way to fine
tracking performance. A vernier height adjustment over an 8 mm range paralleles
the tonearm to the record with any cartridge. This eliminates the added mass of
cartridge spacers, otherwise needed to achieve precise vertical tracking angle.
In all, there are seven tonearm settings and adjustments - from stylus overhang
to cueing height and descent speed - all serving to optimize tracking
performance with any cartridge.
The direct-drive
system of the CS721 is of comparable precision. The the electronically
controlled DC , brushless motor is the smoothest and quietest ever made. A
major contribution to this end result is an exclusive Dual feature: two stacked
coil layers, each consisting of eight coreless bifilar wound coils, that
overlap to achieve a gapless rotating magnetic field. This eliminates the
successive magnetic pulses typical of all other motor designs.
Although the CS721
is Dual's most expensive model, it is hardly the most expensive turntable
available today.
The direct drive
Dual EDS 1000-2 motor, which was developed especially for the hi-fi record
player, is a slow-running, brushless, DC supply electronic motor which gets its
energy from a regulated power supply DC motors typically employ a mechanical
switching commuter, but the Dual EDS 1000-2 utilizes two Hall Generators for
electronic switching Hall Generators regulate four switching transistors
successively to control the four windings of the motor. This cyclic switching
of the field coils produces a rotational field which then causes rotary motion
of the motor. The rotary field coils produce a voltage which is measured and
compared to a voltage standard. Any resultant voltage differential is fed back
and regulated the flow of current in the four switching transistors to regulate
speed. This system of control prevents speed errors freater than 0,025%. The
Dual EDS 1000-2 motor rotor is grooveless and has a magnetic interference
(short circuit terminal), which runs with the rotor.the motor field coils are
non-ferrous and mounted in the air gaps among the eight pole ring magnet of the
rotor and the magnetic short-circuit terminal.
The unique design
described above results in distinct advantages for the Dual EDS-1000-2 Without
pole sensitivity, hysteresis or turbulance current loss and without disturbing
groove frequencies, the Dual EDS 1000-2 guarantees you a completely vibration-free
and unusually steady drive source for your hi-fi recordplayer.
The tonearm of Dual
CS721 meets all the requirements for today's record players; maximum rigidity
with lowest effective mass, and practically negligible bearing friction in the
vertical and horizontal planes.
Studies of
vibrations resulting from tonearm mass, weight, and compliance of the cartridge
have shown that a special design of the tonearm counterbalance can increase
tracking ability considerably, namely when the tonearm counterbalance is
designed to absorb vibration energies within the resonant ranges of tonearm and
chassis.
For this reason, the
inner section of the counterbalance is tuned to the tonearm resonance and has,
due to in phase-opposed vibrations, an anti-resonance effect. By excitation of
the tonearm within the resonance area - energy vibrations between tonearm and
anti-resonator are eliminated. The outer part of the counterbalance, designed
as a higher tuned anti-resonator, prevents the transmission of chassis
resonances to the tonearm.
The design of the
tonearm counterbalance with twp antiresonance filters also improves the
signal-to-noise ratio.
Specifications
Tonearm
Torsionally rigid
tubular aluminum tonearm in low friction four point gimbal suspension, tonearm
counterbalance with two mechanical anti-resonance filters
Effective length of
Tonearm: 222 mm
Offset Angle: 25°20'
Tangential Tracking
Error: 0,16°/cm
Tonearm Bearing
Friction (related to stylus tip)
Vertical : <0,07 mN (0,007 gram)
Horizontal : <0,15 mN (0,015 gram)
Stylus
Pressure: from "0" to 30 mN (0
-3 gram) infinitely variable with 1 mN (0,1 gram) calibrations from
"0" to 15 mN (0 - 1,5 grams) operable from 2,5 mN (0,25 gram) stylus
pressure up
Cartridge
Holder: removable, accepting any
cartridges with 1/2" mounting and a weight from 4,5 to 10 grams (including
mounting hardware)
Adjustable
Overhang: 5 mm
Turntable
Drive:
Electronically-regulated direct-drive system, EDS 1000-2
Power Input: approx. 2,5 watts
Motor at Playing
operation: < 50mW
Power Consumption
(at Start): 60 mA (220 V 50 Hz); 110 mA
(110 V 60 Hz)
Time From Start to
Rated Speed: 2 - 2,5 s at 33-⅓ rpm
Platter: non-magnetic, dynamically balanced,
Mass : 1,5 kg
Diameter : 305 mm
Total Speed Load of
Drive System (rotor with platter) : 3,0
kg
Moment of
Inertia: 250 kp/cm²
Platter Speed: 33-⅓ and 45 rpm. Electronically adjustable.
Automatic tonearm set-down coupled with speed adjustment.
Pitch Control: for
both speeds, adjustable by means of variable resitor, range of regulation: 10%
Speed Contro
(Monitoring)
With illuminated
stroboscope for platter speed 33-⅓
Sensitvity (of the
illuminated strobe for 0,1% speed deviation
3,0 division
markings per minute at 50 Hz
3,6 division
markings per minute at 60 Hz
Total Wow and
Flutter (DIN 45 507) : < ±0,03%
Rumble (DIN 45 500)
Unweighted : >50 dB
Weighted : >70 dB
Line Voltage: 110 to
125 V, 220 to 240 V
Current: AC 50 or 60 Hz
Dimensions (W x H x
D): 424 x 150 x 368 mm
Weight: 8,7 kg
