McIntosh MC-2155 Owners manual
THE MclNTOSH MC 2155 SOLID STATE STEREO
POWER AMPLIFIER
Reading Time: 31 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 2155. 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 im-
portant 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 2155 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 13903-9990
Phone: 607-723-3512
Take Advantage of 3 years
of Contract Service...
Fill in the Application NOW.
Contents
SERVICE 1
INSTALLATION 2
HOW TO CONNECT 4
FRONT PANEL INFORMATION 9
REAR PANEL INFORMATION 11
PERFORMANCE LIMITS AND RATINGS 12
PERFORMANCE CHARTS 13
TECHNICAL DESCRIPTION 15
BLOCK DIAGRAM 17
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 nor-
mal 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 mishan-
dling 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 1981 © by Mclntosh Laboratory Inc. 1
tion 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 6 inches (15.2 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. Remove the MC 2155 from the plastic bag and place it
upside down on the shipping pallet then 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 pane! where the instrument is to be install-
ed, and tape it in place. The broken lines that represent the outline of the rectangular cutout also repressent 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 straight edge.
The PANLOC system of installing equipment conveniently and securely is a direct result of Mclntosh
research. By depressing the two PANLOC buttons
on the front panel, the instrument either 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 build-up 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 ventila-
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 8 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 ½ inch thick, use the ¾ inch
screws: for panels that are more than ½ inch thick,
use the 1 ¼ inch screws.
Starting at the right-hand side of the panel, insert
a screw of proper length into the center hole in the
panel. marked B on the template. 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 slightly 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 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 OPERATION
Use shielded cables to connect the signal from
the preamplifier or signal source to the power
amplifier. To minimize the possibilty 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 2155.
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.
In stereo operation the MODE SWITCH must be in
the STEREO position.
MONOPHONIC OR SINGLE CHANNEL OPERATION
A shielded cable from the signal source is plug-
ged into the Right (Mono) input jack of the MC 2155
only. The MODE SWITCH on the back panel of the
amplifier must be placed in one of the MONO positions. In the MONO positions the output of the right
channel input amplifier is fed to both left and right
power amplifiers. The Left INPUT is disconnected.
Only the signal fed into the Right (MONO) input will
be amplified.
Be certain that the MC 2155 is never operated in
the stereo mode with the outputs connected for
monophonic operation. Should the MODE SWITCH
be left in the STEREO position and the outputs remain strapped for a mono parallel load, one channel
will attempt to drive the other which causes high circulating currents and overheating.
duction for which the loudspeakers have been de-
signed. If undersize wire is used, resistance is added
to the amplifier/loudspeaker combination which
adversely affects the performance. Added resistance causes depreciation of damping characteristics, modification of frequency response and reduction in power output.
Use lamp cord or wire with similar 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 distances of
under 30 feet between the amplifier and speaker, #
18 wire or larger can be used. For distances over 30
feet use larger diameter wire. Select the correct size
wire from the chart below. It is recommended that
the DC resistance of the speaker leads be less than
5% of the speaker impedance. Resistance of the
leads should be computed for the length of wire both
to and from the speaker or speakers.
For multiple speaker operation, run separate
leads from the amplifier to the speakers.
MAXIMUM WIRE LENGTHS
Wire
Gauge
18
16
14
12
10
For 4 Ohm Load
Feet
15
25
40
60
100
Meters
4.57
7.62
12.19
18.29
30.48
For 8 Ohm Load
Feet
30
50
80
120
200
Meters
9.14
15.24
24.38
36.58
60.96
Wire lengths above represent the wire resistance
equal to 5% of the speaker impedance.
OUTPUT
Be certain the loudspeakers connected to the MC
2155 are capable of handling the power output of the
amplifier.
Selection of the proper gauge wire to connect the
loudspeakers preserves the quality of sound repro-
STEREO OPERATION
Check the impedance of the speaker which is
usually identified on the speaker itself or in the
owner's manual. Connect a lead from the common
terminal of the left speaker to the amplifier LEFT
OUTPUT terminal strip COMmon screw. Connect
4
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