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 ⅓ 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 ⅓
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.
Specifications
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 ⅓ 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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