Sony PS-4750 - SPECIFICATIONS

SPECIFICATIONS
Turntable
Platter 13 3/8” (34 cm)
SBMC (Sony Bulk Mould Compound)
Dc servo-controlled motor, direct
drive
Drive system
Speed 33 1/3rpm, 45 rpm
Wow and flutter 0.045% (DIN)
S/N ratio Better than 70 dB weighted
(DIN 45539)
Tonearm
Type Statically balanced, universal
Pivot to stylus length
Overall arm length
237 mm (9 3/8”)
314 mm (12 3/g”)
Overhang 15 mm
Tracking-force adjustment range
0-3g
Shell weight 7.5g
Cartridge weight range 4-12.5g (without extra weight)
12.5-16.5 g (with extra weight)
General
Power requirements 110, 127, 220 or 240 V AC ~
adjustable, 50/60 Hz
Power consumption 6 W
Weight approx. 8.5 kg (181b 12 oz)
approx. 10.6 kg (23 Ib 6 oz) in
shipping carton
477x175x420 mm (18 13/16x
6 7/8x 199/16 inches) (w/h/d)
(including projecting parts and
controls)
45-rpm adaptor
Spacer for cartridge installation
Three pairs of screws for cartridge
installation
Extra weight
Dimensions
Supplied accessories
While the information given is true at the time of printing,
small production changes in the course of our company’s policy
of improvement through research and design might not neces-
sarily be indicated in the specifications. We would ask you to
check your appointed Sony dealer if clarification on any point
is required.
FEATURES
The Sony PS-4750 uses the new material SBMC (Sony Bulk
Mould Compound) in the construction of its turntable platter
and cabinet. Together with the use of a servo-controlled direct
drive de motor, this new material with its unique acoustic and
vibration absorption properties provides an excellent signal-to-
noise ratio.
An innovative frequency sensing device is utilized in the servo
control system in the form of a magnetic coating inside the
platter. This unusual Frequency Generator (F.G.) component of
the servo system, contributes substantially to the exceptionally
low degree of wow-and-flutter.
Newly engineered rubber insulation mats isolate externally
caused mechanical vibrations that would have an adverse effect
on the quality of reproduction.
10
This high compliance, low friction tonearm is provided with a
precisely engineered anti-skating compensator for proper track-
ing and superb reproduction throughout the audio spectrum.
Other features include a high-visibility stroboscope, a built-in
stylus overhang checker, a cueing lever to prevent record and
stylus damage, and convenient pitch controls for accurate tone
reproduction.
SERVO-CONTROLLED SYSTEM PRINCIPLE
A servo-control system is one in which a driven device, in this
case the turntable platter, furnishes an output signal propor-
tional to its speed, then feeds back this signal into a control
mechanism that regulates the input power to the driven device,
so that the speed can be maintained constant at any pre-
determined value.
The servo-controlled system used in the PS-4750 consists of
a dc motor (platter drive) a Frequency Generator (F.G.) incorpo-
rated in the platter itself, and an IC used as the regulating
device, as shown in the block diagram.
When the power is turned on, the dc 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 input frequency.
The dc output in turn controls the output of the dc servo-
amplifier that powers the dc motor. Thus variations in the
drive motor speed are automatically corrected.
If the motor speeds up due to external causes, the output of
the F.G. increases in frequency. This decreases motor voltage
to decrease the motor speed until the F.G. frequency returns
to the nominal value. On the other hand, if the motor slows
down due to external causes, the output of the F.G. decreases
in frequency. This increases motor voltage to increase the
motor speed until the F.G. frequency returns to the nominal
value.
Thus the servo-controlled system maintains an equilibrium con-
dition at the nomimal speed and the motor maintains its selected
speed under varying operating conditions.
Pitch control knobs are provided for vernier adjustments that
permit varying the rotational speed several percent above and
below (+4%) the nominal values of 33-1/3 and 45 rpm.
Drive
motor F.G
DC servo
amplifier