Tube Power Amplifier
MC2301
Owner’s Manual
McIntosh Laboratory, Inc. 2 Chambers Street Binghamton, New York 13903-2699 Phone: 607-723-3512 FAX: 607-724-0549
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IMPORTANT!
INSTRUCTIONS FOR REMOVAL
OF FOAM INSERTS OVER THE
VACUUM TUBES PRIOR TO
CONNECTING THE A.C. POWER
SUPPLY CORD, START ON THE
NEXT PAGE.
3
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Unpacking the MC2301
6. Carefully reinstall the previously removed Tube Cov-
ers and chassis screws on both sides of the MC2301.
Make sure the metal tabs located on the bottom of the
Tube Cover are inserted into the chassis slots. Refer to
figures 6, 7 and 8.
Caution: To prevent damage to the MC2301
Tubes during shipping, there is a spe-
cial foam insert surrounding the Tubes
located on both sides of the Power Am-
plifier.
Note: Only use the chassis screws supplied with the
MC2301. If you can not find the chassis screws,
contact the McIntosh Parts Department for replace-
ments.
BOTH Foam Inserts must be re-
moved from the MC2301 before
connecting the AC Power Sup-
ply Cord to the power amplifier.
7. Save the two Foam Inserts and Warning Sheet with the
MC2301 Shipping Carton for possible further use.
Tube Covers
Failure to do so has the poten-
tial of a Fire Hazard, resulting
in damage to the MC2301 and
the surrounding environment.
Remove Foam
Inserts located
under the Tube
Covers and the
Warning Sheet
Follow the instructions below
for removal of the packing foam
before connecting the AC Power
Supply Cord to the MC2301.
WARNING
TO AVOID A FIRE HAZARD,
THE FOAM INSERTS OVER
THE VACUUM TUBES MUST
BE REMOVED PRIOR TO
CONNECTING THE A.C.
MAINS POWER SUPPLY
CORD AND OPERATING
THIS PRODUCT.
In order to remove the foam inserts surround-
ing the tubes on the MC2301, it is necessary to
temporarily remove the two Tube Covers. After
the foam inserts are removed, the Tube Covers are
re-installed and should not be removed. The cov-
ers provide protection from the hazardous voltages
inside the MC2301. The MC2301 has no user ser-
viceable parts, including the tubes. If repairs are
needed they must be performed by an authorized
McIntosh Service Agency.
REFER TO PAGE 3 IN THE
MC2301 OWNER’S MANUAL
FOR INSTRUCTIONS.
Figure 1
1. Orient the MC2301 so the Front Panel is facing you
and remove the Warning Sheet. Refer to figure 1.
2. Using a Philips Head #2 screw driver, remove the two
chassis screws securing the Tube Cover to the chassis
on both sides of the MC2301. Refer to figure 2.
3. Carefully lift up and remove the Tube Cover from each
side of the MC2301. Refer to figure 3.
Tube Cover
Figure 2
4. Place the Tube Covers and the previously removed
chassis screws in a safe location, as the Tube Covers
will be reinstalled.
Chassis
screws
5. Carefully lift up and remove the Foam Insert from
both sides the MC2301 exposing the Tubes. Refer to
figures 4 and 5.
4
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Unpacking the MC2301 and Ventilation
Figure 3
Figure 4
Foam Insert
Figure 8
Figure 5
Ventilation
Adequate ventilation extends the trouble free life of the
MC2301. Always allow air to flow through the ventilation
holes on the bottom of the amplifier and a means for the
warm air to escape at the top. Refer to figure 9 and the
information on the next page for placement and installation
of the MC2301.
Warm Air
Figure 6
Tube Cover
Cool Air
Figure 9
Figure 7
Chassis
screws
5
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Thank You
Table of Contents
Your decision to own this McIntosh MC2301 Tube Power
Amplifier ranks you at the very top among discriminating
music listeners. You now have “The Best.” The McIntosh
dedication to “Quality,” is assurance that you will receive
many years of musical enjoyment from this unit.
Please take a short time to read the information in this
manual. We want you to be as familiar as possible with all
the features and functions of your new McIntosh.
Safety Instructions.......................................................... 2-3
Unpacking the MC2301 .................................................. 4-5
Thank You and Please Take a Moment.............................. 6
Technical Assistance and Customer Service..................... 6
Table of Contents ............................................................... 6
General Information .......................................................... 6
Connector Information ...................................................... 7
Introduction........................................................................ 7
Performance Features ........................................................ 7
Dimensions ........................................................................ 8
Installation ......................................................................... 9
Rear Panel Connections and Switch.................................11
How to Connect ...........................................................12-13
How to Connect for Bi-Amp........................................14-15
Front Panel Displays and Controls....................................16
How to Operate.................................................................17
Technical Description ..................................................18-21
Specifications................................................................... 22
Packing Instruction.......................................................... 23
Please Take A Moment
The serial number, purchase date and McIntosh Dealer
name are important to you for possible insurance claim or
future service. The spaces below have been provided for
you to record that information:
Serial Number: __________________________________
Purchase Date: __________________________________
Dealer Name: ___________________________________
General Information
Technical Assistance
Caution: The MC2301 Amplifier weight is 116 pounds (52.6
kilograms). It requires two or more persons to safely
handle when moving the amplifier.
1. The following Connecting Cable is available from the McIn-
tosh Parts Department:
If at any time you have questions about your McIntosh
product, contact your McIntosh Dealer who is familiar
with your McIntosh equipment and any other brands that
may be part of your system. If you or your Dealer wish
additional help concerning a suspected problem, you can
receive technical assistance for all McIntosh products at:
Power Control Cable Part No. 170-202
Six foot, 2 conductor shielded, with two 1/8 inch stereo
mini phone plugs.
2. For additional connection information, refer to the owner’s
manual(s) for any component(s) connected to the MC2301.
3. The MC2301 mutes the speaker output for approximately
fifteen seconds when first turned on.
McIntosh Laboratory, Inc.
2 Chambers Street
Binghamton, New York 13903
Phone: 607-723-1545
Fax: 607-724-0549
4. The MC2301 incorporates the very latest in Fully Balanced
Circuitry. As a result, the Loudspeaker
Negative Connec-
tions are above chassis ground. Do not combine any connec-
tions together, ground them or connect with another MC2301
or other Power Amplifier.
Customer Service
If it is determined that your McIntosh product is in need of
repair, you can return it to your Dealer. You can also return
it to the McIntosh Laboratory Service Department. For
assistance on factory repair return procedure, contact the
McIntosh Service Department at:
McIntosh Laboratory, Inc.
2 Chambers Street
Binghamton, New York 13903
Phone: 607-723-3515
Fax: 607-723-1917
Copyright 2008 © by McIntosh Laboratory, Inc.
6
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Connector Information, Introduction and Performance Features
Connector and Cable Information
XLR Connectors
Below is the Pin configuration for the XLR Balanced In-
put, Input/Output Connectors on the MC2301. Refer to the
• Balanced and Unbalanced Input
Balanced connections guard against induced noise and al-
low long cable runs without compromising sound quality.
PIN 3
diagram for connection:
PIN 1
PIN 2
PIN 1: Shield/Ground
PIN 2: + Output
• Sentry Monitor Tube and Thermal Protection
McIntosh Sentry Monitor Tube Protection Circuits ensure
the MC2301 will have a long and trouble free operating
life. Built-in Thermal Protection Circuits guard against
overheating.
PIN 3: - Output
Power Control Connector
The MC2301 Power Control Input receives an On/Off sig-
nal from +5 to +12 volts. The Power
Power
Control
Meter
Illumination
Control Output will in turn provide a
+12 volt Output Signal with a current
up to 20mA. An additional connection
is for controlling the illumination of
• Illuminated Power Meter
The Illuminated Power Output Watt Meter on the MC2301
is peak responding, and indicates the true power output of
the amplifier. The Peak Watt Hold Mode allows the meter
to temporarily stay at the highest power output and then
slowly decay. The Front Panel Meter Illumination may be
switched Off at any time.
Control
Ground
the MC2301 Power Output Meter. The
1/8 inch stereo mini phone plug connects to a McIntosh
A/V Control Center Power Control Output.
Note: The Power Control Connecting Cable is available from
the McIntosh Parts Department:
• Gold Plated Connectors and Tube Socket Contacts
Gold Plated Input Jacks and Output Binding Posts provide
trouble free connections. Ceramic tube sockets with gold
plated contacts provide protection from atmospheric con-
tamination. Output Tube Sockets include Air-Pipe cooling
at their bases.
Data and Power Control Cable Part No. 170-202
Six foot, shielded 2 conductor, with 1/8 inch stereo mini
phone plugs on each end.
Introduction
Now you can take advantage of traditional McIntosh
standards of excellence in the MC2301 Tube Power Ampli-
• Special Power Supply
fier. The 300 watt power output will drive any high quality A regulated Power Supply, a very large core Power Trans-
Loudspeaker System to its ultimate performance. The
MC2301 reproduction is sonically transparent and abso-
lutely accurate. The McIntosh Sound is “The Sound of the
Music Itself.”
former and large capacitors ensure stable noise free opera-
tion even though the power line varies.
• Fiber Optic Solid State Front Panel Illumination
The even Illumination of the Front Panel is accomplished
by the combination of custom designed Fiber Optic Light
Diffusers and extra long life Light Emitting Diodes
(LEDs).
Performance Features
• Power Output
The MC2301 is a Tube Power Amplifier with a capabil-
ity of 300 watts into 2, 4 or 8 ohm speakers with less than
0.5% distortion.
• Glass Front Panel and Super Mirror Chassis Finish
The famous McIntosh Illuminated Glass Front Panel and
the Stainless Steel Chassis with Super Mirror Finish en-
sure the pristine beauty of the MC2301 will be retained for
many years.
• Full Balanced Unity Coupled Circuitry
The MC2301 is fully balanced from input to output. It con-
sists of two matched Power Amplifiers operating in push-
pull using the famous McIntosh Patented Unity Coupled
Circuit. The circuit outputs are combined in a dual core
McIntosh Multifilar Wound Output Transformer for low
distortion, extended frequency response and cool operating
output tubes.
7
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Dimensions
Dimensions
The following dimensions can assist in determining the
best location for your MC2301. There is additional infor-
mation on page 9 pertaining to installing the MC2301 into
cabinets.
17-3/4"
45.09cm
11"
27.94cm
12-5/16"
31.27cm
Front View of the MC2301
17-3/8"
44.15cm
Rear View of the MC2301
12-1/4"
31.11cm
21"
54.61cm
20"
50.86cm
1-5/8"
4.12cm
10-1/2"
26.70cm
3/16"
0.48cm
Side View of the MC2301
1-1/2"
3.81cm
1-3/4"
4.45cm
15-3/4"
40.00cm
8
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Installation
Installation
The MC2301 can be placed upright on a table or shelf,
standing on its four feet. It also can be custom installed in
a piece of furniture or cabinet of your choice. The four feet
may be removed from the bottom of the MC2301 when it is
custom installed as outlined below. The four feet together
with the mounting screws should be retained for possible
future use if the MC2301 is removed from the custom in-
stallation and used free
for clearance. Be sure to cut out a ventilation hole in the
mounting shelf according to the dimensions in the draw-
ing.
1 When the MC2301 is installed together with other McIntosh
Components, check clearances on all components before
proceeding.
standing. The required
panel cutout, ventilation
17-9/16"
44.62cm
cutout and unit dimen-
sions are shown.
Always provide ad-
equate ventilation for
your MC2301. Cool
operation ensures the
longest possible operat-
10 -13/16"
27.46cm
MC2301 Front Panel
Custom Cabinet Cutout
ing life for any elec-
tronic instrument. Do
not install the MC2301
directly above a heat
generating component
such as a high powered
amplifier. If all the com-
ponents are installed in
a single cabinet, a quiet
running ventilation fan
can be a definite asset in
maintaining all the sys-
tem components at the
coolest possible operat-
ing temperature.
12"
Cabinet
Front
Panel
30.48cm
Cutout Opening for Custom Mounting
Opening
for Ventilation
MC2301 Side View
in Custom Cabinet
A custom cabinet instal-
lation should provide
the following minimum
spacing dimensions for
cool operation.
Chassis
Spacers
Cutout Opening for Ventilation
Allow at least 12 inches
(30.48cm) above the top,
2 inches (5.08cm) below
the bottom and 4 inches
(10.16cm) on each side
of the Power Ampli-
fier, so that airflow is
not obstructed. Allow
22 inches (55.88cm)
depth behind the front
panel. Allow 1-5/8
inch (4.12cm) in front
of the mounting panel1
Support
Shelf
2"
5.08cm
17-1/2"
44.45cm
2-1/32"
1.67cm
MC2301 Bottom View
in Custom Cabinet
15-5/16"
38.91cm
14"
35.56cm
Cutout Opening
for Ventilation
Note: Center the cutout Horizontally on the unit.
For purposes of clarity, the above
illustration is not drawn to scale.
9
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Notes
10
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Rear Panel Connections and Switch
BALANCED INput1 / OUTput
for an audio cable from a Pre-
amplifieroutput or to connect an
audio cable on to the next Power
Amplifier input
POWER CONTROL IN
receives a turn On/Off
signal from a McIntosh
component and the
POWER CONTROL
OUT sends a turn On/Off
signal to the next McIn-
tosh Component
Connect the MC2301
power cord to a live AC
outlet. Refer to the rear
panel to determine the
correct voltage
Main Fuse holder,
INPUT MODE switch
refer to information
on the back panel
of your MC2301 to
determine the cor-
rect fuse size and
rating
selects between balanced
or unbalanced input
OUTPUT Connections
for 2 ohm Loudspeaker
OUTPUT Connections
for 4 ohm Loudspeaker
OUTPUT Connections
for 8 ohm Loudspeaker
BALANCED INPUT
for an audio cable
from a Preamplifier
or A/V Control Cen-
ter audio output
Caution: The Loudspeaker
Negative Connections are
UNBALANCED INPUT
for an audio cable from a
Preamplifier or A/V Con-
trol Center audio output
above chassis ground. Do not combine any con-
nections together, ground them or connect with
another MC2301 or other Power Amplifier.
1 This Balanced connector may be used as an Input ONLY when connected to a McIntosh C1000 Preamplifier. For all other connec-
tions use only as an Output.
11
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How to Connect
Caution: The supplied AC Power Cord should not be
connected to the Rear Panel of the MC2301
Tube Power Amplifier until after the Loud-
speaker Connections have been made. Failure
to observe this could result in Electric Shock.
For additional instruction on making Loud-
speaker Connections contact your McIntosh
Dealer or McIntosh Technical Support.
Spade lug or prepared wire connection:
Insert the spade lug connector or prepared section
of the cable end into the terminal side access hole,
and tighten the terminal cap until the cable is firmly
clamped into the
terminal so the
wires cannot slip
1. For Remote Power Control, connect a power control
cable from the Control Center or Preamplifier Power
Control Out to the MC2301 POWER CONTROL IN.
2. Connect a cable from the Balanced Output of a Mc-
Intosh Preamplifier or Control Center to the MC2301
BALANCED INPUT. Place the INPUT MODE Switch
in the BALANCED Position.
out. Refer to fig-
ures 4, 5 & 6.
Banana plug connection:
Insert the banana plug into the hole at the top of the
terminal. Refer to figures A and B.
Note: Banana
Figure 4
Figure 5
Figure 6
Plugs are
for use in
the United
States and
Canada
only.
Note: An optional hookup is to use an unbalanced cable
and place the INPUT MODE Switch in the UNBAL-
ANCED Position.
When connecting Loudspeakers to the MC2301 it is very
important to use cables of adequate size, so there is little to
no power loss in the cables. The size is specified in Gauge
Numbers or AWG (American Wire Gauge). The smaller
the Gauge number, the larger the wire size:
When making Loudspeaker Connections to the MC2301
refer to the Connection Diagram on the next page. This
is an example of a typical audio system, your system may
vary from this, however the actual Loudspeaker would be
connected in a similar manner.
5. Connect the Loudspeaker hookup cables from a single
Loudspeaker to the output terminals that match the im-
pedance of the Loudspeaker, being careful to observe
the correct polarities. Output impedance connections
of 2 ohms, 4 ohms and 8 ohms are provided. If the
Loudspeaker’s impedance is in-between the available
connections, use the nearest lower impedance connec-
tion.
Loudspeaker Cable Distance vs Wire Gauge Guide
25 feet
(7.62 meters)
or less
50 feet
(15.24 meters)
or less
100 feet
(30.48 meters)
or less
Loudspeaker
Impedance
2 Ohms
4 Ohms
8 Ohms
12AWG
14AWG
16AWG
10AWG
12AWG
14AWG
8AWG
10AWG
12AWG
3. This McIntosh MC2301 Tube Power Amplifier is de-
signed for the connection of a single Loudspeaker with
an impedance of 2 ohms, 4 ohms or 8 ohms.
Note: The remaining Loudspeaker Terminals on the
Amplifier should not be connected to another
Loudspeaker.
WARNING: Loudspeaker terminals are hazardous live
and present a risk of electric shock.
6. Connect the MC2301 Power Cord to a live AC outlet.
4. Prepare the Loudspeaker Hookup Cables that attach to
the Amplifier by choosing one of the methods below:
Bare wire cable ends:
Carefully remove sufficient insulation from the
cable ends, refer to figures 1, 2 & 3. If the cable is
stranded, care-
fully twist the
strands together
as tightly as pos-
sible.
Figure 2
Figure 3
Figure 1
Note: If desired,
the twisted ends can be tinned with solder to keep
the strands together, or attach spade lug and/or
banana connector.
12
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How to Connect
McIntosh Preamplifier
McIntosh
Loudspeaker
Connect to
AC Outlet
13
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How to Connect for Bi-Amp
Caution: The supplied AC Power Cord should not be
connected to the Rear Panel of the MC2301
Tube Power Amplifier until after the Loud-
speaker Connections have been made. Failure
to observe this could result in Electric Shock.
For additional instruction on making Loud-
speaker Connections contact your McIntosh
Dealer or McIntosh Technical Support.
1. For Remote Power Control, connect a power control
cable from the Control Center or Preamplifier Power
Control Out to POWER CONTROL IN on the McIntosh
MC2301 Power Amplifier.
2. Connect a power control cable from the McIntosh
MC2301 Power Amplifier POWER CONTROL Out to
the Power Control In on the McIntosh Power Amplifier
Two.
3. Connect a cable from the Balanced Output of a McIn-
tosh Preamplifier or Control Center to the BALANCED
INPUT on the McIntosh MC2301 Power Amplifier.
4. Connect a cable from the BALANCED INPUT/OUT-
PUT of the McIntosh MC2301 Power Amplifier to the
BALANCED INPUT on the McIntosh Power Amplifier
Two. Place the MC2301 INPUT MODE Switch in the
BALANCED Position.
3. If the cable is stranded, carefully twist the strands
together as tightly as possible.
Note: If desired, the twisted ends can be tinned with
solder to keep the strands together, or attach spade
lug and/or banana connector.
Spade lug or prepared wire connection:
Insert the spade lug connector or prepared section
of the cable end into the terminal side access hole,
and tighten the terminal cap until the cable is firmly
clamped into the
terminal so the
wires cannot slip
out. Refer to fig-
Figure 4
Figure 5
Figure 6
ures 4, 5 & 6.
Banana plug connection:
Insert the banana plug into the hole at the top of the
terminal. Refer to figures A and B.
Note: Banana
Plugs are
for use in
the United
States and
Canada
only.
When making Loudspeaker Connections to the MC2301
refer to the Connection Diagram on the next page. This
is an example of a typical audio system, your system may
vary from this, however the actual Loudspeaker would be
connected in a similar manner.
7. Connect the Loudspeaker hookup cables from a single
Loudspeaker to the output terminals that match the im-
pedance of the Loudspeaker, being careful to observe
the correct polarities. Output impedance connections
of 2 ohms, 4 ohms and 8 ohms are provided. If the
Loudspeaker’s impedance is in-between the available
connections, use the nearest lower impedance connec-
tion.
When connecting Loudspeakers to the MC2301 it is very
important to use cables of adequate size, so there is little to
no power loss in the cables. The size is specified in Gauge
Numbers or AWG (American Wire Gauge). The smaller
the Gauge number, the larger the wire size:
Loudspeaker Cable Distance vs Wire Gauge Guide
25 feet
(7.62 meters)
or less
50 feet
(15.24 meters)
or less
100 feet
(30.48 meters)
or less
Loudspeaker
Impedance
2 Ohms
4 Ohms
8 Ohms
12AWG
14AWG
16AWG
10AWG
12AWG
14AWG
8AWG
10AWG
12AWG
5. This McIntosh MC2301 Tube Power Amplifier is de-
signed for the connection of a single Loudspeaker with
an impedance of 2 ohms, 4 ohms or 8 ohms.
Note: The remaining Loudspeaker Terminals on the
Amplifier should not be connected to another
Loudspeaker.
WARNING: Loudspeaker terminals are hazardous live
and present a risk of electric shock.
8. Connect the MC2301 Power Cord to a live AC outlet.
6. Prepare the Loudspeaker Hookup Cables that attach to
the Amplifier by choosing one of the methods below:
Bare wire cable ends:
Carefully remove
sufficient insu-
lation from the
cable ends, refer
to figures 1, 2 &
Figure 2
Figure 3
Figure 1
14
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How to Connect for Bi-Amp
McIntosh Preamplifier
McIntosh
Loudspeaker
Connect to
AC Outlet
McIntosh Power Amplifier Two
15
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Front Panel Displays and Controls
Meter indicates the Power
Output of the Amplifier
Standby Power On and Sentry
Monitor Tube Protection Activa-
tion Indicator
METER Switch selects
the display modes of the
Power Output Meter and
Meter Illumination
POWER Switch Turns
AC Power On/Off, or
On/Remote
16
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How to Operate
How to Operate
Power On
amplifier. The meter pointer will then rise
to the newer higher indication. If no further
power peaks are reached, the meter pointer
will very slowly return to its rest position or
lower power level. The decay rate is approxi-
mately 6dB per minute.
To have the MC2301 automatically turn On or Off when
a control center turns on or off, rotate the power switch to
the remote position. For manual opera-
tion, rotate the power switch to the
On or Off position as desired. Refer to
figure 8.
Note: There must be a power control
Input Mode Switch
connection between the MC2301
and the McIntosh Control Center,
in order for the remote power
turn-on to function.
The Input Mode Switch, which is located on the Rear Panel
of the MC2301, allows you to select either the BAL (Bal-
anced) or UNBAL (Unbalanced) Input. Refer to figure 11.
Figure 8
Standby/Protection Indicator
Meter Selection
The MC2301 Sentry Monitor Tube Protec-
tion Circuitry provides protection to the
Power Amplifier in the event of an imped-
ance mismatch1 between the MC2301 and
the Loudspeaker. It will also activate if
there is a short circuit at the MC2301 Output Terminals (or
the Loudspeaker Terminals) or if a MC2301 Power Out-
put Tube should fail. During normal operation the Sentry
Monitor Tube Protection Circuitry has no effect on the
performance of the Power Amplifier.
Rotate the meter mode switch to
select the meter operation mode
you desire. Refer to figures 9 and
10.
Lights Off - Meter lights are
turned off and the
Figure 11
meter will contin-
ue to indicate the
power output.
Note: When Power
Figure 9
In the event a problem occurs, the MC2301 Sentry
Monitor Tube Protection Circuitry will activate to prevent
potentially destructive high levels of current from flowing
in the amplifier. The Front Panel Standby LED will start
flashing indicating the Protection Circuitry is active. Refer
to the illustration on page 16 for the location of Standby
LED.
To reset the Sentry Monitor Tube Protection Circuitry
place the POWER Switch to the OFF position. After wait-
ing approximately one minute, place the POWER Switch
to the REMOTE or ON position.
Control Input of the MC2301 is connect-
ed to a McIntosh A/V Control Center or
Preamplifier with Remote Meter Illumi-
nation Control, the Meter Illumination
will automatically be remotely con-
trolled (On/Off) with the METER Switch
set to the WATTS or HOLD position.
Watts- The meter responds to all the musical infor-
mation being produced by the amplifier. It
indicates to an accuracy of at least 95% of
the power output with only a single cycle of
a 2000Hz tone burst.
1 This can occur when a Loudspeaker of a given impedance
rating is connected to the MC2301 Output Terminals with a
different impedance rating. For example, a Loudspeaker with
an impedance rating of 2 Ohm is connected the MC2301 8
Ohm Output Terminals. The impedance of a Loudspeaker
actually varies as the Loudspeaker reproduces different
frequencies. As a result, the nominal impedance rating of the
Loudspeaker (usually measured at a midrange frequency)
might not always agree with the impedance of the Loud-
speaker at low frequencies where the greatest amount of
power is required.
Figure 10
Hold - The meter pointer is locked to the highest
power peak in a sequence of peaks. It is
electronically held to this power level until
a higher power peak passes through the
17
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Technical Description
McIntosh Laboratory, the company who introduced the
world’s first amplifier that could be called “High Fidelity”,
has done it again. The McIntosh engineering staff has cre-
20Hz to 20,000Hz. Typical performance at mid frequen-
cies is less than 0.05%. The MC2301 can deliver the best
possible performance from any type of high quality loud-
ated a tube power amplifier without compromise, using the speaker system.
most advanced McIntosh circuit design concepts.
Creating a tube amplifier with this level of performance
A continuous average power output rating of 300 watts
makes this not only the most advanced, but also one of the
most powerful tube amplifiers McIntosh has ever manu-
did not come easily. Many months of design, testing and
measuring were required. Extensive controlled listening
tests, the ultimate form of measuring, were made before
factured. The distortion limits for the MC2301 are no more the final design was accepted.
than 0.5% at rated power output for all frequencies from
Top View of the MC2301
18
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Technical Description
MC2301 Design
McIntosh engineers know how to properly design negative
feedback circuits so they contribute to the low distortion
performance expected from a McIntosh amplifier. Refer to
figure 12. The typical McIntosh owner would never accept
the approximately 25 times higher distortion of many non-
The design philosophy incorporated in the MC2301 in-
volved several different techniques, all based on sound sci-
entific logic. Every stage of voltage amplification must be
as linear as possible prior to the use of negative feedback.
Block Diagram of the
MC2301 Power Amplifier,
Protection Circuitry and
Power Supply
Figure 12
19
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Technical Description, con’t
feedback designs.
are used in all critical circuit locations. The circuit design
of the MC2301 contributes to low operating temperatures
using convection cooling. No fans are needed.
The fully Balanced Push-Pull design is used from input
to output. The resulting fully balanced configuration can-
cels many forms of audible distortion and greatly improves
the Signal-to-Noise ratio of the amplifier.
Power Output Meter
While conventional designs only take output from
the plate, the Patented Unity Coupled Power Amplifier
Circuitry takes the Power Output from both the plate and
cathode of the Power Output Tubes. This allows for only
one half of the turns ratio in the Output Transformer used
in conventional designs. The result is much lower distor-
tion, wider bandwidth and increased loudspeaker damping
factor. Refer to figure 13.
The McIntosh MC2301 has a large Output Watt Meter
that responds 95% full scale to a single cycle tone burst at
2kHz. Refer to figure 15. The voltage outputs are electroni-
cally measured and fed to a special circuit that accelerates
the pointer
movement in
the upward
direction.
When the
pointer
reaches
its peak it
pauses only
long enough
for the hu-
man eye to
perceive its
position,
then drops.
Figure 13
Figure 15
The output signals of the two matched Patented Unity
Coupled Circuit Power Amplifiers operate in a push-pull
balanced circuit and are coupled together in the unique
McIntosh MC2301 Dual Core Output Transformer. Refer
to figure 14. It provides low distortion power transfer at
frequencies from below 20Hz to well beyond 20,000Hz
It is almost 10 times faster than a professional VU meter.
A front panel switch is provided to change the meter to
the Watts Hold Mode of operation. This allows fast upward
movement of the pointer but greatly increases Hold Time
at the peak of its travel. The highest power output of the
source material is thus recorded.
with optimum impedance points of two ohms, four ohms
and eight ohms. The unequaled expertise of McIntosh in
Sentry Monitor Protection Circuit
the design
and manu-
facturing
of trans-
formers is
legendary
in the high
fidelity
The MC2301 incorporates the newly designed Sentry
Monitor Tube Protection Circuitry. Refer to figure 16.
This circuit provides protection to the Power Amplifier in
the event of an improper load (mismatched impedance),
shorted loudspeaker cable or if a Power Output Tube
industry.
Preci-
sion metal
film resis-
tors and
low dielec-
tric absorp-
tion film
Figure 16
capacitors
Figure 14
20
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Technical Description, con’t
should fail. During normal operation there is absolutely no
compromise in sonic performance with this circuit, and it
the next power amplifier occurs at a later time. This helps
prevent power circuit overload that could trip circuit break-
ensures safe operation of the amplifier under even the most ers or blow fuses, a very important feature in a high power
extreme operating conditions.
Home Theater System employing multiple MC2301 Power
In the event a problem occurs, the MC2301 Sentry
Monitor Tube Protection Circuitry will activate to prevent
potentially destructive high levels of current from flowing
in the amplifier.
Power Supply Circuits
To compliment the fully balanced design of the MC2301
the power supply utilizes a very large Power Transformer
(golf ball is for size comparison). Refer to figure 17. It is
Figure 17
enclosed in the legendary McIntosh Potted Enclosures.
The main filter capacitors store energy necessary for the
wide dynamic range that today’s Audio demands. Refer to
figure 16.
Most owners desire one power switch for the whole
audio system. The MC2301 is equipped with a circuit that
provides remote Power Control from a McIntosh A/V Con-
trol Center. When the A/V Control Center is switched On,
a (5-12V) signal operates the power relay in the MC2301.
The MC2301 also has a remote Power Control Out Jack.
The Power Control signal from this jack is delayed by a
fraction of a second so that the turn on power surge of
21
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Specifications
Specifications
Power Output
Power Requirements
Minimum sine wave continuous average power output is:
300 watts into 2 ohm load
300 watts into 4 ohm load
100 Volts, 50/60Hz at 6.6 Amps
110 Volts, 50/60Hz at 6 Amps
120 Volts, 50/60Hz at 5.5 Amps
220 Volts, 50/60Hz at 3 Amps
230 Volts, 50/60Hz at 2.75 Amps
240 Volts, 50/60Hz at 2.75 Amps
Standby: 1 watt
300 watts into 8 ohm load
Output Load Impedance
2, 4 or 8 ohms
Note: Refer to the rear panel of the MC2301 for the correct
voltage.
Rated Power Band
20Hz to 20,000Hz
Overall Dimensions
Width is 17-3/4 inches (45.09cm)
Height is 12-5/16 inches (31.27cm) including feet
Depth is 23 inches (58.42cm) including the Front Panel and
Cables
Total Harmonic Distortion
0.5% maximum harmonic distortion at any power level
from 250 milliwatts to rated power, 20Hz to 20,000Hz
Frequency Response
+0, -0.5dB from 20Hz to 20,000Hz
+0, -3.0dB from 10Hz to 100,000Hz
Weight
116 pounds (52.6 kg) net, 141 pounds (63.9 kg) in shipping
carton
Input Sensitivity (for rated output)
1.7 Volt Unbalanced
3.4 Volt Balanced
Shipping Carton Dimensions
Width is 31 inches (78.74cm)
Depth is 28 inches (71.12cm)
Height is 17-1/4 inches (43.82cm)
Signal To Noise Ratio (A-Weighted)
117dB below rated output
Intermodulation Distortion
0.5% maximum, if the instantaneous peak power output
does not exceed twice the rated power output for any com-
bination of frequencies from 20Hz to 20,000Hz.
Wide Band Damping Factor
Greater than 15
Input Impedance
47,000 ohms
Tube Compliment
2 - 12AT7 Voltage Amplifier
8 - KT88 or 6550 Power Output
22
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Packing Instructions
Packing Instructions
In the event it is necessary to repack the equipment for
shipment, the equipment must be packed exactly as shown
below. It is very important that the four feet are attached to
the bottom of the equipment. This will ensure the proper
equipment location on the bottom foam pad. Failure to do
this will result in shipping damage.
To protect the tubes during shippment, the two Foam
Inserts removed from the MC2301 need to be re-inserted.
Follow the unpacking instructions on pages 3-4 in the
reverse order.
Use the original shipping carton and interior parts only
if they are all in good serviceable condition. If a shipping
carton or any of the interior part(s) are needed, please
call or write Customer Service Department of McIntosh
Laboratory, refer to page 3. Please see the Part List for the
correct part numbers.
Quantity Part Number Description
1
1
2
3
2
034105
034104
034439
034441
034440
Shipping carton top
Shipping carton bottom
Foam Pad (top and bottom)
Foam Ring
Foam Inserts (for protecting
the Tubes during shipping)
Warning Sheet
1
0410900
4
4
400159
018445
10-32 x 3/4 inch screw
Feet
TUBE
COVERS
FOAM
INSERT
FOAM
INSERT
WARNING
SHEET
23
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McIntosh Laboratory, Inc.
2 Chambers Street
Binghamton, NY 13903
The continuous improvement of its products is the
policy of McIntosh Laboratory Incorporated who
reserve the right to improve design without notice.
Printed in the U.S.A.
McIntosh Part No. 04108500
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