Dual C 901 cassette deck

Auto-reverse cassette deck

Dual's first cassette deck, the 901, incorporates every refinement you would expect of an audio component made by Dual; the precision engineering; the clean, understated design, and the quality of materials and German craftsmanship.

It also the first precision cassette deck to incorporate the convenience of automatic revers, continuous playback and bi-directional recording. Significantly, it is the first time Dual's high level of performance and reliability has been available to cassette tape recording.

 

The 901's automatic reverse-system makes it possible to play both sides of a cassette without turning it over. Continuous-play additionally permits a cassette to repeat until the machine is shut off. Recording can be bi-directional.

A photoelectric monitor actuates reversal and shuts off without drag or friction in the tape.

The 901's drive system is unique; using the time-tested Dual Continuous-Pole synchronous motor, it has separate, precision-ground belts to drive the capstan and take-up preventing tape tension variations from affecting tape speed.

The ballistically-damped VU meters of the 901 are typical of its electronic refinements. They are engineered to the exact standards specified for professional equipment.

Optimum usage of the Dolby noise reduction system is assured by a built-in test oscillator which permits precise adjustment to the magnetic characteristics of different tape types.

Other features of the 901 include:

Automatic Level Control as well as a Peak level Indicator to augment the VU meters.

 

Specifications

Tape Speed:  4,76 cm/s

Deviation from Correct Speed:  less than 1%

Wow and Flutter:

DiN 45 507 :  less than 0,12%

WRMS :  less than 0,09%

Frequency Response; 

Standard Tape :  30 - 14,000 Hz

CrO₂ tape :  30 - 16,000 Hz

Dynamic Range

IEC A-Curve :  better than 51 dB

Dolny NR :  better than 60 dB

Distortion (Ref. To 0 dB VU at 333 Hz):  less than 2%

Oscillator :  85 kHz, Push-pull Oscillator

Erasure:  better than 70 dB

Channel Separation:

Between Directions :  better than 60 dB

Between Stereo Channels :  better than 30 dB

Inputs

Mic :  0,22 mV

Radio :  0,22 mV (DIN)

RCA :  0,65 mV

Outputs:

Radio :  0,75 V (DIN)

RCA :  0,75 V

Fast Winding Time:  60 sec for C 60 cassette

Semiconductors:  4 ICs; 3 FET; 31 Transistors; 38 Diodes

Power Requirements:  110 - 130 V or 220 - 240 V, AC 50/60 Hz

Power Consumption:  approx 60 Watts

Dimensions (W x H x D):  420 x 122 x 281 mm

Weight:  6,5 kg

Dual 601 turntable

Precision and performance with the Dual 601. 

Single-play belt-drive automatic turntable

Dual's first medium-priced single-play turntable is also the first Dual to use belt drive. The drive system consists of an 8-pole synchronous motor, developed especially for the 601, and a precision belt which runs directly from the drive shaft to a flywheel rotor beneath the platter. The motor's absolute speed constancy, its exceptional smoothness, and the isolation of the platter from the motor combine to reduce wow, flutter and rumble to an insignificant level.

 

The 601 also features a special anti-skating calibration for CD-4 as well as for conical and elliptical styli.

Other unique features and capabilities include;

low capacitance tonearm leads for full compatibility with CD-4 cartridges;

a 1" dynamically balanced platter, die-cast of non-magnetic alloy;

continuous-play selector which allows the tonearm to play a record once or repeatedly;

and flawless tracking at as low as 0,25 gram.

 

Specifications

Drive:  Dual 8-pole synchronous motor through precision flat belt to platter base.

Platter:  Non-magnetic, dynamically balanced, detachable

Diameter :  305 mm

Weight:  1,3 kg (Platter with flywheel drive, 2,1 kg)

Speeds:  33-⅓ and 45 rpm

Pitch Control Variation: Adjustment range of approx. 1 semitone (approx. 6%) at both platter speeds

Speed Control (Monitoring):  with illuminated stroboscope for all platter speeds, adjustable to 50 or 60 Hz

Illuminated Strobe Sensitivity for Speed  Deviation of 0,1%:

3 bars/min at 50 cps

3,6 bars/min at 60 cps

Wow and Flutter:  less than ±0,08% (According to DIN 45 507)

Rumble (according to DIN 45 500)

Unweighted :  better than 42 dB

Weighted :  better than 63 dB

Tonearm:  Torsion-resistant tubular aluminium tonearm in self-adjusting pivot bearing

Effective Length of Tonearm:  222 mm

Offset Angle:  25° 20'

Tangential Tracking Error:  0,16 degree/cm

Tonearm Bearing Friction (related to stsylus tip)

Vertical :  less than 0,07 mN (0,007 p)

Horizontal :  less than 0,16 mN (0,016 p)

Stylus Pressure:  0 - 30 mN (0 - 3 g). Infinitely variable with 1 mN (1/10 g) calibration from 0 - 15 mN (0 - 15 g) operable from 2,5 mN (0,25 h) stylus pressure up

Cartridge Holder:  removable, accepting any cartridge with 1.2" mounting and weight from 2 to 10 g (including mounting hardware)

Adjustable Overhang:  5 mm

Power Requirements:  110 - 130 V or 220 - 240 V, AC 50/60 Hz

Power Consumption:  approx 10 Watts

Dimensions (W x H x D):  420 x 148 x 365 mm

Weight:  7,6 kg

Dual CS 721 turntable

 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

Dual 1249 turntable

Single-play / multi-play , belt-drive turntable with fully automatic start and stop, plus continuous play. 

Mode selector paralleles tonearm to record in single-play for accurate vertical tracking.

True, four-point gimbal centers and pivots the tonearm mass at intersection of horizontal and vertical axes. Tonearm is dynamical balanced in all planes. The four needle-point pivot are first hardened, then honed, a process which produces microscopically smooth surfaces. The prcision ball-bearing races are only 0,157 inch diameter.

Unique "Vario-pulley" used in Dual three belt-drive models is precision-machined for perfect concentricity and balance. Speeds are adjust by expansion and contraction of pulley circumference, belt is never twisted or distorted.

 

For several years, independent surveys of component owners - audio experts, hifi editors, record reviewers, readers of the music/equipment magazines - have shown that more of them own Duals than any other turntable. This is quite a testimonial to Dual's quality performance, reliability and fully automatic convenience.

We believw the new 1249 will add even more serious music lovers to the roster of Dual owners, as it provides every feature, innovation and refinement long associated with Dual turntables plus some new ones. And all in a newly designed chassis that complements the superb design and meticulous engineering of the 1249.

The low-mass tubular tonearm pivots in a true four-point gyroscopic gimbal suspended within a rigid frame. All tonearm setting are easily made to the exacting requirements of the finest cartridges. The tonearm is vernier adjustable for precise balance, tracking pressure is calibrated in tenths of a gram; anti-skating is separately calibrated for conical, elliptical and CD-4 styli. Tracking is flawless at pressures as low as a quarter of a gram. In single play, the tonearm parallels the record to provide perfect vertical tracking. In multi-play, the Mode Selector lifts the entire tonearm to parallel the center of the stack. All operations are completely flexible and convenient - and they are foolproof. The tonearm can be set on the record manually or by using the viscous- damped cue-control or by simply pressing the automatic switch. You also have the options of single-play, continuou-repeat, or multiple-play. The dynamically-balanced cast platter and flywheel are driven by an 8-pole synchornous motor via a precision-ground belt. Pitch is variable over a 6% range and can be conveniently set to exact speed by means of an illuminated strobe, read directly off the rim of the platter.

 

 

Specifications

Drive:  Dual 8-pole synchornous motor; flat belt for flywheel drive

Starting Time:  approx. 2 sec. (33-⅓rpm)

Platter:  Non-Magnetic, dynamically balanced

Diameter :  305 mm

Weight :  1,3 kg ( platter with flywheel drive 2,1 kg)

Platter Speeds:  33-⅓ and 45 rpm. Automatic tonearm set-down coupled with speed adjustment

Pitch Control Variation:  Adjustment range of approx. 1semitone (approx 6%) at both platter speeds

Speed Control:  with illuminated stroboscope for platter speeds (33-⅓, 45 rpm)

Illuminated Strobe Sensitivity for Speed Deviation of 0,1% :

3,0 bars/min at 50 cps

3,6 bar/minn at 60 cps

Wow and Flutter:  According to DIN 45 507 (GIS < ±0,08%

Rumble (according to DIN 45 500):

Unweighted :  better than 42 dB

Weighted :  better than 63 dB

Tonearm:  torsion-resistant tubular aluminnum tonearm in four-point gimbal

Effective Length:  222 mm

Offset Angle:  25° 20'

Tangential Tracking Error:  0,16 °/cm

Tonearm Bearing Friction (related to stylus tip):

Vertical :  less than 0,07 mN (0,007 p)

Horizontal :  less than 0,16 mN (0,16 p)

Stylus Pressure:  0 - 30 mN (0 - 3 g) Infinitely variable with 1 mN (1/10 g), calibration from 0 - 15 mN (0 - 1,5 g) operable from 2,5 mN (0,25 g) stylus pressure up

Cartridge Holder:  Removable, accepting any cartridges with 1/2", mounting and weight from 4,5 to 10 g

Adjustable Overhang: 5 mm

Current:  AC 50 or 60 Hz, changeable by changing motor pulley

Line Voltage:  110 - 130 V 0r 220 - 240 V , switchable

Power Consumption:  approx. 10 Watts

Dimensions (W x H x D):  420 x 148 x 365 mm

Weight:  7,6 kg

Dual 701 turntable

The Dual 701 is the quietest turntable ever made. Not only in our judgment, but in that of the first independent test laboratory to evaluate its performance. This has been accomplished by an entirely different kind of motor, designed expressly for the 701, and by a very innovative approach to the problem of resonance.

Instead of the familiar, high-speed AC motor, the 701 has an all-electronic, low-speed Dc motor with feedback-controlled speed precision. Because this motor rotates at the record speed, 33-⅓ or 45 rpm, the need for speed-reduction systems such as friction-idler or rim-belt is eliminated. Instead, the platter is rotated directly by the motor, and the record spindle is the top of the motor shaft.

The 701 motor is so quiet and free from vibration that it does not require any isolation mounting but is mounted directly to the chassis. Dual's exclusive design of overlapping coils, a unique feature of the motor, eliminates the successive pulses common to every other existing motor, including other electronic types, high speed or low speed.

 Another Dual innovation serves to prevent interference from reaching and affecting the stylus. Two separate anti-resonance filters, each tuned to a specific resonance range, are located within the counterbalance housing.

One filter is tuned to the resonant range of the tonearm/cartridge system; the other, to the resonant range of the chassis. Each filter serves to cancel out the resonant energy that would otherwise impart spurious signal to the stylus. For those who would like to know more about the 701 motor and the anti-resonance filters.

THE Dual 701 is designed for only single play. But like other Duals, it can be operated either fully automatically, or as a manual turntable.

Because of the unique motor and anti-resonance filters, the 701 is slightly quieter than the 1229. but if you now own a 1229, or any other current Dual, you will detect only a minor difference.

Full-size twelve-inch dynamically balanced, die-cast platter

The 701 platter rests directly on the rotor and rotates with it at the selected speed. Every platter is cost from a single piece of special zinc alloy which is then individually machined and balanced while rotating at high speed. Any imbalances, however minute, are graphically revealed by computerized gauges and precisely corrected. The platter's full twelve-inch diameter, 9,7 pounds of weight (platter plus rotor) and perfect dynamic balance combine to provide optimum flywheel effect.

 

Electronically-regulated, direct-drive motor with exclusive overlapping coil system.

The EDS-1000 motor developed by Dual for the 701 is an all-electronic, low-speed, brushless, DC motor with Hall-effect feedback control, and energized by a regulated power supply. Unlike conventional DC motors, commutation (electrical switching) is not done by brushes and commutator ring. The 701 motor has electronic switching commutation and speed regulation. Two Hall-effect generators drive four switching transistors which produce a rotating magnetic field in the motor's field coils. Depending on the position of the rotor, the magnetic field causes the four magnetic pairs on the rotor to be pushed and pulled continuously. The field coil design is unique and exclusive with Dual. Two stacked coil layers, each consisting of eight bifilar-wound (coreless) coil, offset by 22,5°, achieving a gapless rotating magnetic field that eliminates the successive pulses of magnetic flux typical of all other motor designs. The absence of magnetic spring-back or other rotation irregularities can be demonstrated by turning the rotor manually, no resistance will be sensed. Also, because of the coreless field coils the motor is free of hysteresis or eddy-current losses and the disturbances of pole frequencies.

The rotational speed of the 701 motor is controlled electronically. A voltage which is a function of motor speed is fed to an electronic regulating circuit, and is compared to a constant standard voltage dreived from a regulated power supply. Any difference in these two voltages causes an immediate change in the motor current, hence the motor speed. The rotor is a barium ferrite ring magnet, magnetized in eight segments (poles) on its lower front surface. A steel plate serves as a megnetic return circuit. The regulated power supply makes the speed independent of variations in power-line voltage or frequency. Speed can be set directly to either 33-⅓ or 45 rpm. Thus, the platter is driven directly by the rotor, without need for any speed-reducing linkoge such as friction-idler or rim-belt.

Further, in contrast to the high speed (1800 rpm) vibrations of the conventional AC motor, the 701 motor is so free from vibration that it is mounted directly to the chassis without introducing any rumble. In summary, the 701 electronic direct-drive system, with its over-lapping gapless design, rotating magnetic return circuit and coreless field windings, is the most advanced drive system available for record playback today.

 

Specifications

Drive;  Electronically-controlled direct-drive system Dual EDS-1000

Platter:  Non-magnetic, dynamically-balanced, detachable

Platter Weight:  2,9 kg

Platter Diameter:  305 mm

Total Rotating Mass of Drive System (Rotor with Platter):  4,4 kg, moment of inertia 460 kp/cm²

Run-up Time:  2 - 2,5 sec on 33-1/2 rpm

Platter Speeds:  33-⅓ and 45 rpm  - Electronically switchable, automatic tonearm lowering coupled to speed change

Pitch Control:  Separate for both speed adjustable in each case with variable resistor, with setting scales, range of adjustment 8%

Speed Check:  with light stroboscope for platter speed of 33-⅓ and 45 rpm, adjustable for 50 or 60 Hz

Sensitivity Of Light Stroboscope (for 0,1% Speed Deviation):  6 graduations per minute (at 50 Hz); 7m2 graduations per minute (at 60 Hz)

Overall Speed variations:  less than ±0,03% (DIN 45 507)

 Signal-to-Noise Ratio (DIN 45 500)

Rumble Unweighted :  more than 50 dB

Rumble Weighted :  more than 70 dB

Tonearm:  Torsion resistent, extra long tubular aluminum tonearm in super flat unversal 4-point gimbal suspension, tonearm balance weight with double acting vibration damping (2 anti-resonators)

Effective Tonearm Length:  222 mm

Offset Angle:  25° 20'

Tangential Track Error Angle:  0,16°/cm

Tonearm Bearing Friction (related to stylus point)

Vertical :  < 0,007 p

Horizontal :  < 0,015 p

Tracking Force:  0 - 3 g continuously variable, with 1/10 p calibration in the range from 0 - 1,5p, reliable as from 0,25 p tracking force.

Pick-up Head:  Detachable, suitable for all pick-up cartidges with 1/2" mounting and a deadweight of 2 to 10 g (including mouting material)

Adjustable Overhang:  5 mm

Power Requirements:  110 - 130 V, 220 - 240 V, AC 50/60 Hz

Power Consumption:  2,5 watts (approx), Motor during play <50 mW

Dimensions (W x H x D):  420 x 147 x 365 mm

Weight 10,9 kg

Dual 604 turntable

The Dual 604 is direct drive turntable

You may have noticed that most turntable stories begin and end with the drive system. The tonearm is more or less an afterthought. But not with Dual. Because the tonearm can make a big difference in how records sounds and how long they last. Which is why Dual is very serious about tonearms in our article.

Let's consider the 604 tonearm

The straight-line tubular design provides maximum rigidity with minimum mass. The four-point gimbal centers and pivots the tonearm precisely where the vertical and horizontal axes intersect. And the counter balance houses, two specially-tuned anti-resonance filters that absorb parasitic resonances originating in the tonearm /cartridge system and chassis.

Operation is semi-automatic, with another uniqueDual difference: the machanical sensor. Switch it in and you feel when the stylus is positioned precisely over the 12" and 7" lead-in brooves. At the end of play, the tonearm lifts and returns to its post, and the motor shuts off Automatically.

Now let's talk about the direct-drive system. It employs a newly developed DC electronic motor, with speed regulated by a CMOS integrated circuit and digital reference circuit. Spped accuracy is within 0,001 percent. Wow and flutter are less than 70 dB, as with any great drive system, that's far beyond audibility.

But the important story with any turntable is simply this. The drive system merely turns the record. It's the tonearm that plays it.

Specifications

Drive:  Electronically Regulated Direct-drive system, Dual EDS 500

Speeds:  33-⅓ and 45 rpm, electronically adjustable

Time From Start to Rated Speed:  2 - 2,5 s at 33-⅓ rpm

Pitch Control:  Separate for both speeds, each adjustable by means of variable resistor with calibration scale of regulation; 10%

Speed Control (Monitoring):  with illuminated stroboscope for platter speeds 33-⅓ and 45 rpm, adjustable to 50 or 60 Hz

Sensitivity of the Illuminated Strobe:  6 division marking per minute at 50 Hz, 7,2 division marking per minute at 60 Hz

Platter:  Non-magnetic, dynamically balanced

Platter Diameter/Weight:  300 mm / 1,3 kg

Wow and Fluuter:  according to DIN 45 507 (GIS) less than ±0,06%

Rumble (DIN 45 500): 

Unweighted :  better than 45 dB

Weighted :  better than 65 dB

Tonearm:  Torsionally rigid tubular aluminum tonearm in low-friction four-point gimbal suspeension, 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

Vertical :  less than 0,07 mN (0,007 g)

Horiziontal :  less than 0,16 mN (0,016 g )

Stylus Pressure:

From 0 to 30 mN ( 0 to 3 g) infinitely variable with 1 mN ( 1/10g) calibrations

From 0 to 16 mN (0 to 1,5 g) operable from 2,5 mN (0,25 g) stylus pressure up

Power Input:  apprx. 2 watts, Motor at playing operation less than 50 mW

Power Supply:  110 V -125 V, 220 V - 240 V, AC 50/60 Hz

Power Consumption:  at Start 25 mA at Play 15 mA (220 V, 50 Hz); at Start 65 mA at Play 25 mA (110 V, 60 Hz)

Weight:  4,6 kg

Dual CS-510 turntable

The new Dual model 510 meets the need of that special breed of audiophile who prefers to handle the tonearm himself. At the same time, the 510 tonearm provides important automatic features that we believe even the most sure-handed music lover will appreciate.

When the tonearm is raised from its resting post and moved toward the record, there's no need to guess when it is precisely over the lead-in groove; a mechanical sensor lets you know for both 12" and 7" records. The tonearm then will not descend until the cue-control lever is actuated. You don't even have to remember to set the cue-control in the up position (it automatically resets at the end of play)

All this is achieved by the 510's unique indexing indicator which is interlocked with the cue-control. However, if you don't want this help, you can simply switch the system off.

There are two other touches of automation. Moving the tonearm toward the record turns on the drive system. At the end of play, the tonearm lifts and the motor shuts off.

In all other respects, the 510 is essentially the same as other full-sized Dual models.

The tonearm is mounted in a newly designed four-point gimbal suspension. It is vernier-adjustable for precise balance; tracking pressure is calibrated in tenths of a gram for use with the most advanced cartridges; anti-skating is separately calibrated for conical, elliptical and CD-4 styli

The dynamically-balanced cast platter is linked to an 8-pole synchronous motor through a precision-ground belt. Pitch is variable over a 6% range (a semitone) and can be conveniently set to exact speed by means of a built-in illuminated strobe, read directly off the rim of the platter.

Features of Dual 510:

Tonearm pivots in both axes within four-point gimbal

The 510 tonearm pivots horizontally and vertically an identical sets of low-friction needle-point bearings. Each gimbal is hand-assembled, and special gauges assure that each will conform to Dual's stringent specificaations. For example, vertica; friction must measure no more than seven thousandths of a gram or that gimbal will not pass quality control

Stylus pressure applied around pivot maintans dynamic tonearm balance

A long flat spring coiled around the pivot applies constant stylus pressure throughout play. Only a small portion of the spring's length is used, thus maintaining accurate pressure from 0,25 gram up. Tonearm balance is maintained throughout play, and stylus pressure remains perpendicular to the record even if the turntable is tilted.

8-pole synchronous motor, precision-ground belt drive and dynamically-balanced platter.

The 510 belt-drive system features a specially developed 8-pole synchronous motor that achieves high starting torque and exceptionally smooth, vibration-free rotation.

The precision-ground belt serves three functions with ingenious simplicity; it acts as the speed reduction system; rotates the platter; and isolates it  from any residual motor vibration.

The full-size, 2-inch platter is a one-piece aluminum casting individually machined and then monitored for perfect balance using computer-controlled gauges.

Specifications:

Drive:  Dual eight pole synchronous motor via precision flat belt on turntable platter

Start-up Time:  2 s at 33/1-3 rpm (until nominal speed is reached)

Platter: non-magnetic, detachable,

Weight:  1,3 kg

Diameter:  300 mm

Platter Speeds:  3-1/3 and 45 rpm

Pitch Control Variation:  for 33-1/3 and 45 rpm records, adjustment range of approx. 1 semi-tone (approx. 6%) at both platter speeds

Speed Control:  with illuminated stroboscope for platter speed 33-1/3 rpm

Sensitivity of Stroboscopic Light for 0,1% Speed Variation:

3 locating marks/min at 50 Hz

3,6 locating marks/min at 60 Hz

Wow and Flutter:  less than ±0,08% (according to DIN 45 507)

Rumble (DIN 45 500)

Unweighted :  better than 42 dB

Weighted :  better than 63 dB

Tonearm:  Torsion- resistant tubular aluminium tonearm in four point gimbal

Effective Lenght of Tonearm:  222 mm

Offset Angle:  25° 20'

Tangential Tracking Error:  0,16°/cm

Tonearm Bearing Friction (related to stylus tip):

Vertical :  less than 0,07 mN (0,007 p)

Horizontal :  less than 0,16 mN (0,016 p)

Stylus pressure:

From 0 - 30 mN ( 0 - 3 g) infinitely variable with 1 mN ( 1/10 g) calibrations

From 0 - 15 mN (0 - 1,5 g) operable from 5 mN ( 0,5 g) stylus pressure up

Cartridge Holder:  Removable accepting any cartridge with 1/2" mounting and weight form 5,5 to 10 g (including mounting hardware)

Adjustable Overhang:  5 mm

Power Requirements:  110 - 130 V or 220 - 240 V (switchable), AC 50/60 Hz

Power Consumption: approx. 10 Watts

Dimensions (W x H x D):  420 x 148 x 365 mm

Weight:  4,3 kg

Dual C830 cassette deck

The Dual C830 is a machine that not only handles ferric, chrome, ferrichrome andd metal tapes, it has two values of bias for both ferric and chrome tapes, thereby providing an optimum bias match for all commonly used formulations. Though it has a three-head system with simultaneous record-play, there is no simultaneous Dolby decorder; the simultaneous monitor exactly reproduces the recorded sound - the Dolby decoder is active only in the play mode. A record limiter cuts in at 0 dB record level with a fasy attack and release, thereby protecting against unsuspected excessive signal pecks. The record level indicator is not frequency compensated and indicates the true peak value after record pre-emphasis is applied. The 12-step LED record level indicator is very easy to read.

The C830 has a direct-access front loading mechanism, automatic stop at the end of play and a memory reset counter. It also features adjustable headphone volume, microphone/line input mixing and fade-erase during playback.

Comes in a metal cabinet

Specifications

Type:  Single cassette tape deck

Track System:  4 Tarack, 2 Channel Stereo

Heads:  1 for Record/Playback;  2 for Erase

Tape Speed:  4,75 cm/s

Pitch:  Control range ±4%

Wow and Flutter :  ±0.035% (WRMS)

To DIN, playback only :  ±0,07%

To DIN, recording/plauback :  ±0,10%

Frequency Response  (ref. To DIN tolerances):

Standard Fe Tape :  20 - 17,000 Hz

CrO₂ Tape :  20 - 18,000 Hz

FeCr Tape :  20 - 19,000 Hz

Pure Metal Tape :  20 - 20,000 Hz

Signal-to-Noise Ratio (with Dolby NR)

Fe Tape : 67 dB

CrO₂  Tape :  67 dB

FeCr Tape :  69 dB

Metal :  69 dB

Channel Separation (at 1000 Hz)

Between Stereo Channels :  40 dB

Between Channels (in opposite direction) :  70 dB

Erasure (at 1000 Hz):  70 dB

Oscillator Frequency (push/pull oscillator):  105 kHz

Inputs Sensitivity/Impedance:

Microphone Jack :  0,3 mV/5 k Ω

Amplifier/Receiver DIN Jack :  1 mV/10 k Ω

Amplifier/Receiver RCA Jack :  80 mV/47 k Ω

Outputs Load/Impedance

Amplifier/Receiver DIN Jack :  0-580 mV/10 k Ω

Amplifier/Receiver RCA Jack :  0-580 mV/2 k Ω

Headphones Jack :  4 - 2000 Ω

Fast Wind Time (C-60 cassette):  60 sec.

Line Voltage:  115 volt and 230 volt

Line Frequency:  50/60 Hz

Power Conssumption:  15 W

Dimensions (W x H x D):  440 x 150 x 360 mm (17,2" x 5,9" x 14,2")

Weight:  20 pounds

Dual C839 RC cassette deck

The Dual 839 is so different from all other cassette decks that, rather than list its many features, we'll guide you through them as if the 839 were in front of you.

First, the 839 is bi-directional in record and playback. This doubles the length of every cassette. You'll notice there's no door between you and the cassette compartment. Insert a cassette and it will lock in precise alignment.

That's Dual Direct Load and lock system. (a subtle but important touch; any slack in the tape is immediately taken up.)

Follow us carefully on his next one. Even when the tape is in motion, you can pull it out and replace it with another,  and the previous mode resumes automatically. Useful? When the tape nears the end at a crucial moment, you can have a new tape in place without missing beat.

The 839 is just as innovative in playback. If a tape made on another deck is too sharp or too flat, no problem. Playback pitch can be varied over an 8 percent range.  And previously recorded tapes with clicks, pops and disc jockey interruptions can be cleaned up electronically - smoothly and permanently. Dual's fade/edit control lets you do that with complete confidence, because it functions in playback.

Back to recording. He peak-level LED indicators react faster than any other metering system. And more accurately, because they're equalized. They read the full processed signal - including the high frequency boost other decks add but only Dual reads. No more risk of overloading a tape into distortion.

There's still more. Much more. Full metal record and playback. 6-way bias/equalization. Two-motor, twin-capstan drive system.

Computer logic solenoid-activated controls. Switchable multiplex filter. Switchable limiter. Line/mic mixing. Two-way memory stop with automatic replay. Headphone level controls. And operation by external timer or optional wireless remote control.

What about the 839's audible performance? The specifications can give you a hint. Wow and flutter ±0,3 percent WRMS. Frequency Response from 20 Hz to 20 kHz, ±3 dB. Signal-to-Noise  is better than 69 dB

Specifications

Type:  Single cassette tape deck

Track System:  4 Tarack, 2 Channel Stereo

Heads:  1 for Record/Playback;  2 for Erase

Tape Speed:  4,75 cm/s

Pitch:  Control range ±4%

Wow and Flutter :  ±0.03% (WRMS)

To DIN, playback only :  ±0,06%

To DIN, recording/plauback :  ±0,09%

Frequency Response  9ref. To DIN tolerances):

Standard Fe Tape :  30 - 18,000 Hz

CrO₂ Tape :  30 - 19,000 Hz

FeCr Tape :  30 - 19,000 Hz

Pure Metal Tape :  30 - 20,000 Hz

Signal-to-Noise Ratio (with Dolby NR)

Fe Tape : 64 dB

CrO₂  Tape :  64 dB

FeCr Tape :  67 dB

Metal :  67 dB

Channel Separation 9at 1000 Hz)

Between Stereo Channels :  35 dB

Between Channels (in opposite direction) :  60 dB

Erasure (at 1000 Hz):  70 dB

Oscillator Frequency (push/pull oscillator):  105 kHz

Inputs Sensitivity/Impedance:

Microphone Jack :  0,25 mV/10 k Ω

Amplifier/Receiver DIN Jack :  0,5 mV/6,3 k Ω

Amplifier/Receiver RCA Jack :  40 mV/82 k Ω

Outputs Load/Impedance

Amplifier/Receiver DIN Jack :  0-580 mV/10 k Ω

Amplifier/Receiver RCA Jack :  0-580 mV/2 k Ω

Headphones Jack :  4 - 2000 Ω

Fast Wind Time (C-60 cassette):  65 sec.

Line Voltage:  115 volt and 230 volt

Line Frequency:  50/60 Hz

Power Conssumption:  40 W

Dimensions (W x H x D):  440 x 150 x 360 mm

Dual C 830 cassete deck

Three Head Cassette Deck

Dual  C 830 front loading stereo cassette deck offers three heads for true tape monitoring during recording, full record/playback metal capability, and electronic fade/edit for rediting during playback. A phase-locked loop DC servo motor with integral frequency generator provides highly accurate and stable tape drive, according to the manufacturer. Logic-controlled tape-transport functions and an electronic tape-motion sensor prevent jams and tape spills. A unique Dual Direct Load and lock System (DLLS) eliminates hinged cassette door and provides automatic head protection during insertion and removal of a cassette. A six-way bias/equalization switch includes a setting for new metal tapes. Equalized LEDs provide peak-level indications.

Other features; twin-belt drive system; two-way line/MIC mixing; switchable limiter circuit; headphone level controls; MPX filter switch; Dolby noise reduction; left/right microphone inputs; Sendust record and playback heads.

Specifications

Motor:  PLL DC servomotor type

Heads / Composition:  3 / Sendust, high flux

Speed Accuracy:  less than 0,4%

Wow and Flutter (WRMS):  ±0,035%

Frequency Response (±3 dB, w/MPX filter switched out):

With Ferric Oxide :  20 zh - 17 kHz

With Chromium Dioxide :  20 Hz - 18 kHz

With Ferrichrome :  20 Hz - 19 kHz

With Metal ;  20 Hz - 20 kHz

Signal-to-Noise Ratio (Dolby in):

Ferric Oxide tape :  better than 67 dB

Chromium Dioxide  tape :  better than 67 dB

Ferrichrome tape :  better than 69 dB

Metal tape :  better than 69 dB

Harmonic Distortion:  less than 0,4%

Erasure at 1 kHz :  better than 70 dB

Cross Talk

In Opposite Direction:  better than 70 dB

Between Stereo Channels ;  better than 40 dB

Fast Wind Time (C-60):  65 sec

Dimensions:  17-3/16" x 5-3/4" x 13-3/8"