Audio Dynamics Pritchard ADC-85 User manual

Pritchard Pickup System
models ADC-85 & 40
AUDIO DYNAMICS CORPORATION
1677 CODY AVENUE. RIDGEWOOD 27, NEW YORK

SPECIFICATIONS
Tone arm accommodates other cartridges.
The system comes completely assembled and wired, and is
provided with a cable assembly ready to plug into amplifier.
The arm-cartridge combination is balanced in all planes
making it very insensitive to external shock. No leveling of the
turntable is required; in fact perfect tracking may be obtained
with the turntable tilted as much as 30° to the horizontal.
The geometry of the arm is arranged to give minimum trac
ing distortion and not minimum tracking error. (The reasoning
behind this is based on the fact that a given tracking error in
the inner record grooves produces more distortion than the
same degree of tracking error in the outer grooves.)
A unique integrated arm rest is incorporated in the tone
arm, eliminating the need for separate mounting of an arm
rest.
General Description
The Pritchard Pickup System consists of the superb ADC-1
cartridge combined with an entirely new tone arm especially
designed to provide the finest possible pickup performance.
The arm has a very low moment of inertia necessary for
stable tracking at % gram. To stabilize the centripetal force
created by friction between the stylus and the record, a side
thrust compensator is provided. This results in an even
pressure on both groove walls-essential for distortion-free
stereo reproduction. Precision, single ball bearings in gimbals
reduce vertical and lateral friction to a negligible quantity.
Drag is further reduced by a unique wire guide so arranged
that the ultra-fine lead wires twist along their own axis.
The body of the arm is accurately machined from specially
treated walnut which suppresses extraneous resonances and
insures that the arm adds no “color" to the reproduction.
A plug-in shell is provided for convenient removal of the
cartridge and additional shells may be used to accommodate
other high compliance cartridges.
Arm length
Pivot to stylus tip
Rear overhang 13/4”
Fundamental resonance 6cycles/sec. (with ADC-1 cartridge)
System tracks at 3/4 gram.
105/8”overall
9"

Installation of Arm
Your Pritchard Pickup System is a precision
instrument built to the highest engineering standards.
It should, therefore, be treated with every
reasonable care.
It is suggested that the plug-in shell be removed
during installation in order to protect the
cartridge and stylus.
Removable plug-in head
(E) Side thrust lever
(B) Tone arm rest
Side thrust
compensator
(A)
Red colored crosscut
(D)
Set screw
(C)
(F) Gimbal assembly
(G) Rear counterweight

1.Mounting The Arm
You may use the inner box on which the
arm is mounted as a template for location
of the pivot post hole by inverting the box,
placing hole "B” over the turntable spindle
and inserting a pencil or other marking
instrument in hole “A” right through the
thickness of the box.
The pivot post position is located in the
arc described by the path of the pencil.
Note, however, that the point of the arc
chosen to locate the exact position of the
pivot post should be such that the arm itself
is free to swing from the "rest” position to
the center of the record.
a wood baseboard, three woodscrew starting
holes will be necessary. Using the machine
screws, nuts and washers, or woodscrews
provided, secure the base firmly to the
baseboard.
Positioning The Tone Arm
2 .
3 .Adjusting Tracking Pressure
Adjust height of tone arm by slackening
the set screw (C) in base and moving pivot
post up or down until the bottom of the
wooden tone arm just clears the edge of a
record placed on the turntable.
Be sure that the gimbal assembly (F) is
turned so that the arm is free to move over
the playing area of the record and yet drop
into the arm rest at a convenient position
alongside the turntable.
The arm may be mounted in any conveni
ent position on the baseboard. For optimum
tracking the stylus should overhang the
center of the turntable by
After locating the pivot post center, drill
aor 5/8”hole at this point. Center
the base accurately over the hole and mark
the centers of the three mounting screw
holes.
If ametal baseboard is used, three holes,
1/8”in diameter, must be drilled. In case of
The correct tracking pressure (3/4gram
for the ADC-1) is obtained by adjusting the
rear-counterweight (G) clockwise or counter
clockwise until the desired pressure is
achieved.

Electrical
Cartridge Mounting
Right Channel Hot-Red
Right Channel Ground - Green
Left Channel Hot-Yellow
Left Channel Ground -Black
In those cases where the arm is supplied
without a cartridge, or it is desired to mount
a different cartridge in the shell, the mount
ing hardware supplied may be used. The
connections for the shell leads are as
follows:
A cable assembly is supplied in order to
conveniently connect the tone arm leads to
the amplifier. The five-pin plug should be
inserted in the socket at the base of the
pivot post. The phono plug attached to the
grey cable should be inserted in the right
channel amplifier input socket and that hav
ing the black cable in the left channel
socket. The black ground lead should be
connected to the amplifier ground.
The thread attached to the side thrust
compensator (A) should be draped over the
tone arm rest (B) as shown in the illustra
tion. For tracking pressures of 1 gram or
less, the thread attached to side thrust lever
(E) should be looped around the groove
nearest to the pivot. For higher pressures,
the outer groove should be used.
To measure tracking pressure, any accu
rate gram gauge calibrated from 2to 8
grams may be used. First rest the stylus
anywhere on the record. Then, place the
gauge under the arm at aposition indicated
by the red colored crosscut (D). Lift the
arm with the gauge. When the stylus just
comes clear of the record surface, note the
reading of the gauge and divide this reading
by four, e.g., agauge reading of 3grams
indicates apressure of 3/4gram; areading
of 6grams indicates apressure of 11/2
grams, etc. If asufficiently accurate gram
gauge that measures below 1gram is avail
able, you may, of course, measure tracking
pressure at the stylus tip in the conven
tional manner.

Don’t
Apply lubricating oil
Transport arm without
first removing plug-in-head
Clean treated wooden tone
arm with abrasive cleaning
fluids or materials
guaranteed for 1 year against defects in materials
and workmanship.
If, under normal use, mechanical defects de
velop, and if the cartridge, stylus or arm has not
been abused, misused or tampered with, it will
be repaired or replaced without cost. You have
only to return the attached warranty form within
10 days of purchase. Unit should be sent directly
to:
GUARANTEE
Every Pritchard PicKup System, cartridge and
stylus is precision-crafted of the finest materials.
These are carefully tested at Audio Dynamics
laboratory. The ADC-1 stereo cartridge is guar
anteed forever and the stylus assembly guaran
teed for one year against defects in materials and
workmanship. The arm alone (ADC-40) is also
Service Department AUDIO DYNAMICS CORPORATION
1677 Cody Avenue, Ridgewood 27, New York
Do
Remove the plug-in shell before
installation
Handle the arm with care
Check the gimbal assembly before
tightening set screw to be sure
arm can move from the “rest”
position to the center of the
record
Return the enclosed warranty card
If you follow the foregoing instructions carefully, the Pritchard Pickup System will perform
perfectly.

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