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FEATURES
Your
PS-6750
assures
excellent
signal-to-noise
ratio and excep-
tionally tow-degree of wow-and-flutter due to:
eServo-controlled
direct drive de motor
@innovative
frequency
generator for servo-controlled
system
e@Non-resonant
material
SBMC
(Sony
Bulk
Mould
Compound)
used for case
Other featuring characteristics
are:
@ Sensitive carbon fiber tonearm reducing resonance interference
@ Precisely manufactured rubber insulation mat isolating mechani-
cal vibrations
@ Height-adjustable
resilient feet absorbing
external vibration
SERVO-CONTROLLED
SYSTEM
PRINCIPLE
A servo-controlled
system
is one
in which
a driven
device,
in
this case the turntable
platter, maintains the motor speed con-
stant at any predetermined value by furnishing the output signal
proportional to its speed, then feeding
back
this signal
into
a
control
mechanism
that regulates the input power to the driven
device.
The
servo-controlled
system
used
in the PS-6750
consists of a
dc motor (platter drive), a frequency generator (hereafter called
F.G.) and an IC servo amplifier as a regulating device, as shown.
The F.G. takes, in the PS-6750,
the form of a magnetic coating
around
the turntable
and
a sensing
head
inside the platter.
Drive motor
When
the power
is turned
on,
the
de servo
motor
begins
its
operation.
A frequency proportional to motor speed is produced
by the F.G., then passed through the IC processing circuit where
it is converted
to a dc output proportional
to the frequency.
The dc output in turn
controls the output of the dc servo ampli-
fier that
powers
the dc
motor.
Thus
variations
in the
drive
motor
speed
are automatically
perceived.
If the motor speeds
up due
to an
external cause,
the output
of the F.G. increases in frequency by +4f.
This decreases motor
voltage: to reduce
the
motor
speed
until
the
F.G.
frequency
returns tofo.
On the other
hand, if the motor slows down, the
output
of the
F.G.
decreases
by
—4f.
This
increases
motor
voltage
to augment
the
motor speed
until
the
F.G.
frequency
returns
to fo.
+Av
Operating
point at the predetermined
Wo
speed
—Av
SAS
fo
+f
Frequency produced by F.G.
Output
voltage
of the
motor
10
Thus the servo-controlled system maintains an equilibrium condi-
tion at fo and the motor maintains its selected speed
under vary-
ing operating
conditions.
Pitch controls
are
provided
for vernier adjustments
that permit
varying the rotational
speed by +4%
of the nominal
values of
33 1/3 and 45 rpm.
SPECIFICATIONS
Turntable
Platter
32cm
(12 5/g"), diecast aluminum
alloy
Drive system
Dc sevo-controlled motor, direct drive
Speeds
33 1/3 and 45 rpm
Speed
control
range
+4%
Starting time
Within
1/2 turn (33 1/3 rpm)
Wow
and flutter
Less than
+0.045%
(DIN 45 507
weighted)
S/N ratio
Better than 70 dB (DIN 45 539,
B-curve
weighted)
Tonearm
Type
Statically balanced
237 mm
(9 3/3")
320 mm
(12 5/8")
Pivot to stylus length
Overall arm
length
Overhang
15mm
(5/g")
Tracking error
+2°30'
~—1°20'
Tracking-force
adjustment
range
0-3 g
Arm
height adjustment
range
O-7mm
Shell weight
10.5g
4-10g
(without extra weight)
10-15g
(with extra weight)
Cartridge weight range
General
Power
requirements
110,
127,
220
or 240V
ac ~
(adjustable),
50/60 Hz
—factory-set at 220V
Power consumption
6W
Dimensions
Approx.
442 x 182 x 390 mm (W/H/D)
(Approx. 17 3/gx 7 3/16
x 15 3/8")
including
projecting
parts and
controls
Net: approx.
10 kg (20 Ib 10 0z)
In shipping carton:
approx.
13 kg
(28 lb 7 oz)
45-rpm
adaptor
Alignement
Protractor
Spacer for cartridge height adjustment
Cartridge mounting
screws
3 pairs
Screwdriver for cueing
height
adjustment
Arm
height adjustment
lever
Extra weight
Shell
Phono
cord
1 set
Weight
Supplied
accessories
While the information
given is true at the time of printing, small
production
changes
in the
course
of our
company's
polcy
of
improvement
through
research and design might not necessarily
be indicated
in the specifications.
We
would
ask you to check
your appointed
Sony dealer
if clarification
on
any
point is re-
quired.
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