Sansui SR 717 Brochure

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Sansui has engineered this direct-drive
transcription turntable with particular
attention to three key qualities: precision.
stability and durability. When it comes to
performance. vibrations you can't hear
can. indeed, be extremely harmful to
faithful reproduction of musical timbre

DIRECT-DRIVE ELECTRONIC TRANSCRIPTION TURNTABLE

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and nuances. The Sansui SR-7f7 protects
you from all motor vibration by driving
the high-inertia platter directly with a DC
servomotor with its own solidvslate elec-
tronic control system. The S-shaped
tonearm with friction-free Sansui support
reduces all tracing distortion And the no-

howl cabinet does away with resonance
Sansui uses superhardened steel alloy
and other advanced materials throughout
to ensure impressive performance over
long use. When you listen to a record on
the Sansui SPF/'17. all you Will hear is
what is on the record. not under it.

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One of the finest manual turntables ever made.
Sansui s SR-717 has S/ N of 60dB,wow/flutter of 0.035%.

SUPER-PRECISION

DIRECT-DRIVE DESIGN

20-Pole Brushless DC Servomotor

The platter. platter shaft and direct-drive
DC servo-controlled motor of the $3717
are virtually one wholly-integrated piece of
precision machinery. Motor speed is
identical to platter speed. reducing all
chance of rumble. unwanted vibration
and rotation error caused by mechanical
linkages, The 20-pole brushless DC motor
developed by Sansui operates flawlessly
on less power. generates less heat and
induction hum and IS subject to
significantly less speed deviation than even
the finest motors used in belt~drive or
rim-idler type systems.

0.6. SERVOMOTOH SCHEMATIC DIAG RAM

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Individually-Balanced Precision Platter
The SR-7t7 is not affected by changes
in platter load. This is due in part to
the precision design of the 30cm
aluminum alloy die-cast platter with its
individually-balanced. high-inertia
characteristics and heavy weight (1 4kg).
Durability and stability are further assured
with the use of a Superhard spindle.
speCIal alloy sleeve and heavy-duty
lubricant originally developed by
the spacecraft induslry.

Impressive Performance

The direct~drive motor and heavy platter
contribute to rarely-achieved excellence
in performance a signal 60dB and a wow/flutter of 0.035%,
The sturdy deSign means this performance
is provided over years of use. And the
extra-thick (6mm) platter mat completely
absorbs harmful vibration. further
improving signal-topoise and resusting
acoustic feedback while protecting
your records

Sansui Exclusive Position~Sensor

The SR-717 employs a unique Posnion-
Sensor built inside the rotor magnet.
This Sansui-exclusive engineering
innovation uses the two coils on the bllilar
Winding in each slot. one coil to
continuously detect the preCise position
of the rotor and the other coil to drive
the motor. The mechanism is error-free
and needs no adjustment.

Solid-State Control

The Position-Sensor registers the sine-
wave voltage caused by the moving rotor.
This IS passed on as a control signal to
the servomotor. A high-gain. solid-state
servoamplifier is used in this sophisticated
circuit. together with high~precision parts.
to assure minimum rotation drift and
maximum resistance to load change.
The motor ignores changes in supply
voltage and provides su per-accurate
rotation speed at all times

PROFESSIONAL STROBO

SPEED CONTROL

Visual Check on Precise Rotation

The outer rim of the platter on the SR-717
is engraved with dotlike stroboscopic
calibrations. When illuminated with the
pulsing light of the built-in strob lamp.
these dots enable immediate visual
confirmation of platter rotation speed.
The four lines of dots. top to bottom. are:
lli33Vgrpm. 50Hz. i2i33V3rpm. 60Hz;
t3i45rpm. 5OH2. C4}45rpm. 60Hz

Use of Stroboscope and Pitch Controls
First. select rotation speed (33%. or
45rpml by use of the leather-touch
Speed Select buttons. These are entirely
electronic and use no mechanical links.
Then. as the platter rotates. observe the
line of dots corresponding to selected
speed and the frequency of AC voltage
in your area. It the dots appear to "creep"

forward or backward. adjust the speed of
the platter with the Pitch Control for that
speed until they appear to stand still
Adjustment range is i4% from rated
speed. Fine-tuning your platter enables
you to reproduce all musical sounds on
any record With perfect pitch.

D-C MOTOR START/CONTROL BLOCK DIAGRAM

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