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

Mitsubishi LT-20

 Linear Tracking - Significantly Improved performance
Like the top-of-the-line LT-30, the LT-20 uses the same Mitsubishi linear-tracking technology. Freed, by this important technical innovation from the tracking errors and unbalanced inside forces that affect conventional turntable units, there is a truly remarkable increases in the transparency and clarity of the audio image, and in the spatial definition of the stereo sound field. The stylus follows the same straight line across the disc as the cutting head that made the original master recording, so that tracability is at a maximum and distortion at an absoulte minimum.

The Linear-Tracking Mechanism
A high precision Dc servomotor drives a worm-reduction gear attached to a spring-loaded multistrand nylon coated stainless-steel wire to move the tonearm assembly. The whole system is located firmly in position, unlike linear motors where the assembly is free to slip and slide.
The precise amount of movement needed to maintain tangential tracking as the groove spirals inward is determined by two sensitive optical sensors. These detect when the tonearm moves even a fraction of a degree from the tangent position.
 Smooth, Stable Tracking System for High S/N Ratio
The signal-to-noise ratio of the LT-20 is an unusually high 75 dB (DIN-B) higher rhan many conventional turntable units, a tribute to the smooth, silent movement of the tonearm assembly on its precision runners.

Simple, Positive Adjustment
Adjustment of tracking force - often a problem on some competitive units - could hardly be simpler; a milled knob on the main tonearm assembly is used to zero balance the cartridge, and then the subweight is moved along the tonearm pipe to give the desired tracking force. The setting is easy to make, highly accurate, and readily visible.
Simple vertical adjustment of tonearm height is also provided, so that all cartridges can be accomodated with the tonearm perfectly parallel to the platter surface.
 High-Resolution Anti-Resonant Tonearm
The LT-20's linear-tracking tonearm is short and straight, unlike the long S- or J-shaped conventional arms. This , and the choice of stainles steel for the pipe - offering the ideal combination of rigidity and strength - gives a tonearm with an extremely low effective mass of only 13,9 grams,free of obtrusive resonances. The low mass makes an important contribution to the ease and accuracy of tracking, even with warped discs. A special filling of anti-resonant butyl rubber helps to reduce resonances still further, for the clean, clear-cut sound that distinguishes Mitsubishi linear -tracking turntable units.
The combination of a radial ball bearing and two wide span lateral pivot bearings ensures a stable, sensitive, low-friction assembly. Oxide-free copper wires are used to carry the low-current phono-cartridge signal to your phono inputs, ensuring minimum resistive losses and improved audio quality.
 Fully Automatic Control Using and LSI Computer on-a-Chip
Our first generation of electronic logic controlled turntable units used many individual Ics to give the new, user oriented features. The LT-20 uses a special purpose LSI device that gives flexibility, with increased reliability and a comprehensive range of automatic functions. As explained earlier in this catalog, it takes the signals from the operating controls and from the photoelectric sensors that detect the presence and size of the disc on the platter, and guides the stylus to the lead in groove. At the same time it chooses 45 rpm for 7" and 33 rpm for 12" discs.
Other functions are:
Auto lead-in :  press the start control and the tonearm moves to the first track on the disc, gently lowering the stylus to commence play.
Auto return :  at the end of the disc, the tonearm lifts and returns to its rest position.
Auto cut :  play can be ended at any point during disc audition.
Free access lead-in :  the stylus can be traversed to the left to start audition from the track of your choice. Speed of traverse automatically slows over the disc surface.
Auto repeat :  the same disc can be repeated as many times as you wish.
Lift-up and cueing :  the stylus can be alternately raised an lowered at the touch of a control.
Free travel :  the stylus may be raised and traversed freely to the left or right, from track to track at either of two speeds - fast for rapid approach and slow for fine positioning - by either pressing the controls continuously.
Quick response :  any movement except lift/cue of the stylus can be interrupted by a new command.
Stylus protection :  when there is no disc on the platter, the stylus will not descend and the tonearm will return to rest protecting the stylus and cartridge from serious damage.
 Platter Speed Under Quartz Crystal Oscillator Control.
The word 'Quartz" in the illuminated window at the center of the LT-20's control panel is your guarantee that platter speed is either 33 or 45 rpm - precisely. It illuminates as soon as the direct-drive motor speeds the platter  up to rated revs. A built-in frequency generator produces a frequency that is compared with a standard reference frequency generated by a quartz crystal oscillator.
A rapid response feedback circuit locks these two frequencies together so that the platter always rotates synchronously. The combination of the ultimate in accuracy with the simple, reliable and effective direct-drive mechanism ensures low wow and flutter both now and throughout a long useful life.

Other Important Features and Functions
Ideal headshell design.
Overhang former.
Lighty smoked polystyrene dust cover.
Anti-howling design.
Convenient Operating Controls
Speed selector switch;
Start control;
Stop control;
Lift/Cue control;
Repeat control.
Type:  Direct-Drive logic-controlled fully automatic linear-tracking
Drive System:  Quartz PLL DC servomotor direct drive
Platter Diameter:  304 mm , diecast aluminum
Platter Weight:  1,3 kg (2 lb 14 oz)
Speeds:  33 and 45 rpm
Wow and Flutter:  0,025% WRMS
Signal-to-Noise Ration:  75 dB (DIN-B); 60  dB (IEC-B)
Tonearm Type:  Straight type universal static balance
Lenght Overall / Effective:  220 mm (8-11/16") / 171 mm (6-3/4")
Effective Mass Tonearm:  13,9 g without cartridge
Overhang:  0 mm
Offset Angle:  0°
Tracking Angle Error:  maximum 0,1°
Headshell weight:  GFRP type, 6,2 g
Cartridge Weight Range:  10 - 21,5 g with headshell
Output Capacitance:  55 pF
Power Requirements:  110 or 240 V , 50/60 Hz
Power Consumption:  14 W
Dimensions (W x H x D):  424 x 141 x 417 mm (16-3/4" x 5-1/2" x 16-3/8")

Weight:  10 kg (22 lbs)

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