Dual 491 - Antiskating and Pitch Control; Tonearm Indexing and Platter; Service and Technical Data; Service Information

Antiskating
The skating force which acts upon any pick-up arm causes one-
sided wear on the needle and on the record and can cause
distortion in the reproduction.
To compensate for skating force, a counterforce, precisely de-
fined in weight and direction, must be applied to the tonearm.
The anti-skating mechanism (8) of your turntable fulfills this
requirement.
Separate calibrations are provided for the stylus types used al-
most exclusively today, according to the imprinted symbols:
© setting for conical stylus
© setting for biradial (elliptical) styli
CD 4 setting for playing CD 4 records with special CD 4 cartrid-
ges
The setting of anti-skating compensation corresponds to the
setting of stylus pressure: Turn the anti-skating knob to the
number on the appropriate scale which corresponds to the
stylus pressure you have set. That is, for a stylus pressure of
15 mN (1.5 grams), set the anti-skating knob also at “1.5”
When playing records moistened with a cleaning agent, the
skating force is reduced by approximately 30 %. In such cases
we recommend a corresponding 30 % decrease in antiskating
compensation.
Pitch control
Each of the two standard speeds (33 1/3 and 45 rpm) can be
varied with the pitch control (15).
The pitch control maintains the nominal speed and provides
for individual control of tempi and pitch of reproduction, for
example, when the pitch of recorded music is to match a live
musical instrument, or when a record passage is to match the
length of a motion picture scene. Adjustment is made with
pitch control knob (15).
The illuminated strobe mechanism can be used to adjust the
exact speeds while a record is playing. When the turntable
rotates at exact speed no movement of the bars is observed. If
the bars appear to advance in the same direction as the turn-
table the speed is too high. If the bars appear to retreat, the
speed is too low.
The platter
The effective rotating mass platter consists of two parts, the
rotor of the electronically-regulated direct-drive motor and
the aluminum die-cast platter with a total weight of 1.0 kg.
The platter rests directly on the rotor and is secured to it by
gravity alone.
Important! Remove platter prior to each transport!
Adjustment of tonearm indexing
If playing of a record is started automatically, the stylus
is lowered automatically into the starter groove of the re-
cord.
If the stylus of another cartridge, installed later, sets down too
far inside or outside the lead-in groove, adjustment can be made
as follow:
Move the speed selector to 33”. Removing the decorating strip
(first lift it on the rear edge) will expose the control (Fig. 5)
for tonearm indexing.
Place a 12” record on the platter and start the unit. If the sty-
lus sets down too far inside or outside the center of the record,
turn adjusting screw clockwise or counterclockwise, respecti-
vely.
Turn the adjusting screw clockwise or anticlockwise until the
pickup needle is lowered accurately into the starter groove.
16
Service
All lubrication points are adequately supplied with oil prior to
delivery to the customer. Under normal conditions, your Dual
should function properly for many years; do not oil any part
of your Dual yourself. Should your player ever require service,
please take it to your Dual dealer, or ask him for the address of
the nearest authorized Dual service station. Please make sure
that only original Dual replacement parts are used.
Should shipping of your Dual become necessary, make sure
that the packing is adequate.
Use, if possible, the original packing material in which you re-
ceived your unit.
Electrical safety
This player meets international safety standards for radio and
related equipment (IEC 65).
Technical data
Current
AC 50 to 60 Hz
Line voltage
115 V, 230 V
Drive
electronically-regulated direct-drive system, Dual EDS 500
Power input approximately 2 watts
Motor at playing operation 50 mW
Platter
non-magnetic, detachable 1 kg, 270 mm diameter
Platter speed
33 1/3 and 45 rpm, electronically adjustable
Pitch control
Separate for both speeds, each adjustable by means of variable
resistor, with calibration scale; range of regulation: 10 %
Speed control (monitoring)
with illuminated stroboscope for platter speeds 33 1/3 and
45 rpm, adjustable to 50 or 60 Hz.
Wow and flutter
DIN, IEC #0,07%
WRMS + 0,05%
Rumble (according to DIN, IEC)
Unweighted: > 43 dB
Weighted: > 64 dB
Tonearm
Torsionally rigid tubular aluminum tonearm in low-friction
four-point gimbal suspension.
Tonearm bearing friction (related to stylus tip)
vertical <0.08 mN (0.008 g)
horizontal <0.15 mN (0.015 g)
Stylus pressure
from 0 to 50 mN (0 to 5 g) infinitely variable
Cartridge holder
removable, accepting any cartridges with 1/2” mounting and a
weight from 4.5 to 10 grams (including mounting hardware).
Adjustable Overhang
5mm
Cartridge
see separate data sheet