McIntosh MC-502 User Manual
THE MclNTOSH MC 502 POWER AMPLIFIER
Reading Time: 28 Minutes
Price $2.00
VARIOUS REGULATORY AGENCIES REQUIRE THAT WE BRING THE
FOLLOWING INFORMATION TO YOUR ATTENTION. PLEASE READ IT
CAREFULLY.
WARNING: TO PREVENT FIRE OR SHOCK
HAZARD, DO NOT EXPOSE THIS UNIT TO
RAIN OR MOISTURE.
The Mclntosh you have purchased is a Model MC
502. It has a serial number located on the rear panel
of the chassis. Record that serial number here:
Serial Number
The model, serial number and purchase date are
important to you for any future service. Record the
purchase date here:
Purchase Date
Upon application, Mclntosh Laboratory provides a
Three-Year Service Contract. Your Mclntosh
authorized Service Agency can expedite repairs
when you provide the Service Contract with the instrument for repair. To assist, record your Service
Contract number here:
Service Contract Number
Your MC 502 Stereo Power Amplifier
will give you many years of pleasant and
satisfactory performance. If you
have any questions, please contact:
CUSTOMER SERVICE
Mclntosh Laboratory Inc.
2 Chambers Street
Binghamton, New York 13903
Phone: 607-723-3512
Take Advantage of 3 years
of Contract Service ...
Fill in the Application NOW.
Contents
HOW TO INSTALL... 2,3
HOW TO CONNECT... 4
THE FRONT PANEL CONTROLS
AND HOW TO USE THEM... 7
REAR PANEL INFORMATION... 8
PERFORMANCE LIMITS... 9
PERFORMANCE CHARTS ...10,11
TECHNICAL DESCRIPTION ...12,13
BLOCK DIAGRAM...14
MclNTOSH THREE YEAR SERVICE CONTRACT
An application for A THREE YEAR SERVICE CONTRACT is included with this manual.
The terms of the contract are:
1. Mclntosh will provide all parts, materials
and labor needed to return the measured
performance of the instrument to the
original performance limits. The SERVICE CONTRACT does not cover any
shipping costs to and from the authorized service agency or the factory.
2. Any Mclntosh authorized service agency
will repair Mclntosh instruments at normal service rates. To receive service
under the terms of the SERVICE CONTRACT, the SERVICE CONTRACT CERTIFICATE must be presented when the
instrument is taken to the service agency.
3. Always have service done by a
Mclntosh authorized service agency. If
the instrument is modified or damaged
as a result of unauthorized repair, the
SERVICE CONTRACT will be cancelled.
Damage by improper use or mishandling is not covered by the SERVICE
CONTRACT.
4. The SERVICE CONTRACT is issued to
you as the original purchaser. To protect you from misrepresentation, this
contract cannot be transferred to a second owner.
5. To receive the SERVICE CONTRACT,
your purchase must be made from a
Mclntosh franchised dealer.
6. Your completely filled in application for
the SERVICE CONTRACT must be post-
marked within 30 days of the date of
purchase of the instrument.
7. To receive the SERVICE CONTRACT, all
information on the application must be
filled in. The SERVICE CONTRACT will
be issued when the completely filled in
application is received by Mclntosh
Laboratory Incorporated in Binghamton,
New York.
8. Units in operation outside the United
States and Canada are not covered by
the Mclntosh Factory Service Contract,
irrespective of the place of purchase.
Nor are units acquired outside the
U.S.A. and Canada, the purchasers of
which should consult with their dealer
to ascertain what, if any, service contract or warranty may be available locally.
Copyright 1979 © by Mclntosh Laboratory Inc.
1
The PANLOC system of installing equipment conveniently and securely is a product of Mclntosh
research. By depressing the two PANLOC buttons
on the front panel, the instrument slide can be locked firmly in place or it can be unlocked so that the
chassis can slide forward, giving you easy access to
the top and rear panels.
The trouble-free life of an electronic instrument is
greatly extended by providing sufficient ventilation
to prevent the buildup of high internal temperatures
that cause deterioration. Allow enough clearance so
that cool air can enter at the bottom of the cabinet
and be vented from the top. With adequate ventilation the instrument can be mounted in any position.
The recommended minimum space for installation
is 15 inches (38.1 cm) deep, 17 inches (43.2 cm) wide,
and 4-1/2 inches (11.4 cm) high.
To install the instrument in a Mclntosh cabinet,
follow the instructions that are enclosed with the
cabinet. For any other type of installation follow
these instructions:
1. Open the carton and remove the PANLOC
brackets, hardware package, and mounting
template from the carton. Remove the MC 502 from
its plastic bag and place it upside down on the shipping pallet; unscrew the four plastic feet from the
bottom of the chassis.
2. Mark the cabinet panel.
Place the mounting template in the position on the
cabinet panel where the instrument is to be install-
ed, and tape it in place. The broken lines that repre-
sent the outline of the rectangular cutout also repre-
sent the outside dimensions of the chassis. Make
sure these lines clear shelves, partitions, or any
equipment. With the template in place, first mark the
six A and B holes and the four small holes that
locate the corners of the cutout. Then, join the four
corner markings with pencil lines, using the edge of
the template as a straightedge.
3. Drill Holes
Use a drill with a 3/16 inch bit held perpendicular to
the panel and drill the six A and B holes. Then, using
a drill bit slightly wider than the tip of your saw
blade, drill one hole at each of two diagonally opposite corners. The holes should barely touch the inside edge of the penciled outline. Before taking the
next step, make sure that the six A and B holes have
been drilled.
4. Saw the Panel Cutout
Saw carefully on the inside of the penciled lines.
First make the two long cuts and then the two short
cuts. After the rectangular opening has been cut out,
use a file to square the corners and smooth any irregularities in the cut edges.
2
5. Install the Mounting Strips
In the hardware package you will find two mounting
strips, and two sets of machine screws. For panels
that are less than 1/2 inch thick, use the 3/4 inch
screws; for panels that are more than 1/2 inch thick,
use the 1-1/4 inch screws.
Starting at the right-hand side of the panel, insert
a screw of the proper length into the center hole in
the panel, marked B on the templete. On the back of
the panel, align a mounting strip with the holes in
the panel and tighten the screw until the screwhead
is pulled into the wood.
Repeat this procedure to attach the mounting
strip to the left side of the panel.
6. Attach the PANLOC Brackets
Using two screws of the proper length in the A holes
on each side, attach the PANLOC brackets to the
cabinet panel; the short flange is mounted against
the front (face) of the cabinet panel. The screws
pass through the PANLOC bracket flange, the
cabinet panel, and then through the mounting strips
previously mounted.
7. Install the Instrument
Guide the AC power cord through the panel opening
to the back of the cabinet; then, slide the instrument
into the opening carefully so that the rails on the
bottom of each side of the chassis engage the
tracks on the mounting brackets. Continue to slide
the instrument into the cabinet until it is stopped by
the adjust position latches. Press the latches inward, this permits the instrument to slide into the
cabinet until its front panel is flush with the cabinet
panel. Depress the PANLOC buttons at the lower left
and right corners of the instrument panel to lock the
unit firmly in the cabinet. Depressing the PANLOC
buttons again will unlock the instrument so that it
can slide forward to the adjust position; if you press
inward on the adjust position latches then you can
remove the instrument from the cabinet.
3
How to Connect
INPUT
STEREO OR TWIN AMPLIFIER OPERATION
Use shielded cables to connect the signal from
the preamplifier or signal source to the power
amplifier input. To minimize the possibility of hum
the shielded cables should be run parallel to each
other or loosely twisted together. Locate the cables
away from speaker leads and AC power cords. All
connections are made on the back panel of the MC
502.
For stereo operation, the left output of the
preamplifier should be plugged into the Left input
jack of the power amplifier. The right output of the
preamplifier should be plugged into the Right
(MONO) input jack of the power amplifier.
MONOPHONIC OR SINGLE CHANNEL OPERATION
A shielded cable from the signal source is plugged into the Right (MONO) input jack of the MC 502
only. The MODE SWITCH on the back panel of the
amplifier must be placed in the MONO position. In
the MONO position the right channel input jack connects to both amplifiers. The Left INPUT is disconnected.
OUTPUT
Selection of the proper gauge wire to connect the
loudspeakers preserves the quality of sound repro-
duction for which the loudspeakers have been designed. If undersize wire is used, resistance is added
to the amplifier/loudspeaker combination which
adversely affects the performance. Added resistance causes reduction of damping characteristics,
modification of frequency response and reduction in
power output.
Use lamp cord, bell wire, or wire with similar type
of insulation to connect the speakers to the amplifier. In all cases, the leads to and from the speaker
should be twin conductor or twisted together. When
using 8 ohm speakers and for the normally short dis-
tances of under 30 feet between the amplifier and
speaker, No. 18 wire or larger can be used. For
distances over 30 feet between the amplifier and
speaker use larger diameter wire. Select the correct
size wire for the wire length from the chart. It is
recommended that the DC resistance of the speaker
leads be less than 5% of the speaker impedance. Up
to 10% can be tolerated. Resistance of the leads
should be computed for the length of wire both to
and from the speaker or speakers.
MAXIMUM WIRE LENGTHS
Wire
Gauge
22
20
18
16
14
12
10
Wire lengths above represent the wire resistance equal to 5%
of the speaker impedance.
For 4 Ohm Load
Feet
6
10
15
25
40
60
100
Meters
1.8
3.1
4.6
7.6
12.2
18.3
30.5
For 8 Ohm Load
Feet
12
20
30
50
80
120
200
Meters
3.7
6.1
9.1
15.2
24.4
36.6
66.0
For multiple speaker operation, run separate
leads from the amplifier to the speakers.
CONNECTING LOUDSPEAKERS FOR STEREO
Connect the leads from the left loudspeaker to the
Left and Common OUTPUT terminals on the MC 502.
Connect the leads from the right main loudspeaker
to the Right and Common terminals.
CONNECTING ONE LOUDSPEAKER FOR MONO
Connect leads from the loudspeaker to the Left
and Right OUTPUT terminals on the MC 502. Check
to be sure the MODE switch is in the MONO posi-
tion.
In MONO operation neither output terminal (Left
or Right) is at ground potential. The output is balanced to ground. Due precaution is required when connecting test instruments since neither terminal can
be grounded.
AC POWER
The amplifier AC power cord is plugged into a 120
volt 50/60 Hz wall outlet.
FUSE
A 4-amp fuse protects the MC 502 circuits. The
fuse does not protect additional equipment connected to the rear panel AC power outlets.
4
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