What is stereo?




There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.




H.H. Scott '59





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

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