Dual 701 Owners Manual

Page 1

Dual '10]

Automatic single play turntable
with electronically regulated direct drive

Page 2

Contents.

Page 2 (flap) Introduction.

Page 3 (flap) Features of the Dual 701.

Page 4 Operating instructions.
Page 5 Direct-drive motor.

Page 6-7 Tonearm of the Dual 701.
Page 8-9 Installation instructions.

Introduction.

Although the Dual 701 is a highly sophisticated
turntable, you will probably find it simpler and easier
to operate than any other turntable you have owned.
For example, one operating switch controls all
automatic start and stop functions of the motor and
tonearm. And whether you start it manually or
automatically, play can be interrupted at any time,
either manually or automatically.

Thus, much of this owner's manual is devoted
to a description of the 701s advanced features,
especially the electronically regulated direct-drive
motor and the mechanical filters.

We do suggest, however, that you fol low the
cartridgemou nti ng instructions with some care. As
with any tonearm, the stylus must be in the correct
position for optimum performance. We are confident
that you will now enjoy your records more than
ever before.

If you have any questions about tre 701s
operation or performance, we hope you wi I write to us.
In any case, we would appreciate your corr ments on
the warranty card which we urge you to co nplete and
send in for proper registration of your 701.

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400 A

Tonearm of the Dual 701.

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Vertical onearrli re son ancL. .

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Fig. 8. Curves show how the tonearm/
cartridge anti-resonant filter attenuates
the resonance of three cartridges, each
weighing 4.5 grams and with stylus
compliances of 15, 25 and 43. Broken
lines show resonance without filter; solid
lines show attenuated resonance with
filter.

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Fig. 9. Influence of anti-resonant filter is
shown when tonearm is dropped on
grooveless record from 4mm height.
Resonance is quickly damped out by filter,
whereas resonant influence continues
much longer without filter.

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Fig. 10. Filtertunedto resonance frequency
of chassis attenuates resonances in
rumble range. Effectiveness of filter is
compared with use of similar but non-
filtered counterbalance.

6

A brief explanation of resonance
and the mechanical filters.

Tonearms, turntables and
cartridges have mechanical
resonances as do all physical objects.
Such resonances interfere in record
playback performance by introducing
peaks and dips in the frequency
response of the cartridge, by causing
spurious low-frequency peaks, and by
excessive sensitivity to acoustical
feedback.

Various damping and coupling
techniques have been used over the
years to minimize these effects of
resonance-with varying but modest
degrees of success. The ideal solution
for tonearm resonance would be to
eliminate its effect on stylus
performance. In the Dual 701, this is
accomplished by two separate
mechanical filters housed within the
tonearm counterbalance.

Each of the filters is tuned to a
range of frequencies encountered by
the playback system. One filter is
designed to cancel the effects of the
chassis and its suspension; the other
is tuned to cancel the resonance of
the tonearm/cartridge combination.

One final note: this solution to
the problem of the unwanted effects
of resonance has been accomplished
without complex engineering devices
which might introduce other
problems.

EIastically-damped counterbalance
containing mechanical resonance
filters.

This unique counterbalance
does more than provide the correct
counterweight for the front of the
tonearm including mounted cartridge.
It also houses two separate
mechanical filters; one is tuned to
vibrate within the resonance range of
the tonearm and cartridge, the other
within the range of the chassis and its
m0unting hardware.

Unlike all other turntables
which are designed to have their
resonant frequencies tuned below the
audible range, the Dual 701 eliminates
these resonances by absorbing any
energy that appears at these
frequencies. The result is flatter
frequency response and greater
isolation from acoustical feedback.

Four-point gimbal suspension with
needle-point bearings.

All four suspension points of
the tonearm are identical, low-
friction, needle-point bearings. Each
gimbal is hand-assembled and
individually checked with gauges
especially developed by Dual for
this purpose.

With horizontal friction below
fifteen thousandths of a gram, this
tonearm is easily capable of tracking
at as low as a quarter of a gram.

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Dual Gebrfider Steidinger - 7742 St.Georgen/Schwarzwald Edit 1073