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Tube Power Amplifier
MC2301
Owner’s Manual
McIntosh Laboratory, Inc.
2 Chambers Street Binghamton, New York 13903-2699 Phone: 607-723-3512
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FAX: 607-724-0549
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The lightning flash with arrowhead,
within an equilateral triangle, is
intended to alert the user to the
presence of uninsulated “dangerous voltage” within the product’s
enclosure that may be of sufficient
magnitude to constitute a risk of
electric shock to persons.
The exclamation point within an
equilateral triangle is intended to
alert the user to the presence of important operating and maintenance
(servicing) instructions in the literature accompanying the appliance.
WARNING - TO REDUCE RISK OF
FIRE OR ELECTRICAL SHOCK, DO
NOT EXPOSE THIS EQUIPMENT TO
RAIN OR MOISTURE.
IMPORTANT SAFETY
INSTRUCTIONS!
PLEASE READ THEM BEFORE
OPERATING THIS EQUIPMENT.
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean only with a dry cloth.
7. Do not block any ventilation openings. Install in
accordance with the manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus
(including amplifiers) that produce heat.
9. Do not defeat the safety purpose of the polarized
or grounding-type plug. A polarized plug has two
blades with one wider than the other. A grounding type plug has two blades and a third grounding prong. The wide blade or the third prong are
provided for your safety. If the provided plug does
not fit into your outlet, consult an electrician for
replacement of the obsolete outlet.
10. Protect the power cord from being walked on or
pinched particularly at plugs, convenience receptacles, and the point where they exit from the
apparatus.
2
NO USER-SERVICEABLE PARTS
INSIDE. REFER SERVICING TO
QUALIFIED PERSONNEL.
To prevent the risk of electric shock, do not remove cover or
back. No user-serviceable parts inside.
11. Only use attachments/accessories specified by the
manufacturer.
12. Use only with the cart, stand, tripod, bracket, or
table specified by the manufacturer,
or sold with the apparatus. When a
cart is used, use caution when moving the cart/apparatus combination
to avoid injury from tip-over.
13. Unplug this apparatus during lightning storms or
when unused for long periods of time.
14. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has
been damaged in any way, such as power-supply
cord or plug is damaged, liquid has been spilled or
objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not
operate normally, or has been dropped.
15. Do not expose this equipment to dripping or
splashing and ensure that no objects filled with liquids, such as vases, are placed on the equipment.
16. To completely disconnect this equipment from the
a.c. mains, disconnect the power supply cord plug
from the a.c. receptacle.
17. The mains plug of the power supply cord shall
remain readily operable.
18. Do not expose batteries to excessive heat such as
sunshine, fire or the like.
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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.
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Unpacking the MC2301
Caution: To prevent damage to the MC2301
Tubes during shipping, there is a special foam insert surrounding the Tubes
located on both sides of the Power Amplifier.
BOTH Foam Inserts must be removed from the MC2301 before
connecting the AC Power Supply Cord to the power amplifier.
6. Carefully reinstall the previously removed Tube Covers 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.
Note: Only use the chassis screws supplied with the
MC2301. If you can not find the chassis screws,
contact the McIntosh Parts Department for replacements.
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 potential 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 surrounding 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 covers provide protection from the hazardous voltages
inside the MC2301. The MC2301 has no user serviceable parts, including the tubes. If repairs are
needed they must be performed by an authorized
McIntosh Service Agency.
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.
4. Place the Tube Covers and the previously removed
chassis screws in a safe location, as the Tube Covers
will be reinstalled.
5. Carefully lift up and remove the Foam Insert from
both sides the MC2301 exposing the Tubes. Refer to
figures 4 and 5.
4
REFER TO PAGE 3 IN THE
MC2301 OWNER’S MANUAL
FOR INSTRUCTIONS.
Figure 1
Tube Cover
Figure 2
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Chassis
screws
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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
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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
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:
McIntosh Laboratory, Inc.
2 Chambers Street
Binghamton, New York 13903
Phone: 607-723-1545
Fax: 607-724-0549
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:
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 McIntosh Parts Department:
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.
4. The MC2301 incorporates the very latest in Fully Balanced
Circuitry. As a result, the Loudspeaker
Negative Connections are above chassis ground. Do not combine any connections together, ground them or connect with another MC2301
or other Power Amplifier.
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 Input, Input/Output Connectors on the MC2301. Refer to the
PIN 3
diagram for connection:
PIN 1
PIN 2
PIN 1: Shield/Ground
PIN 2: + Output
PIN 3: - Output
Power Control Connector
The MC2301 Power Control Input receives an On/Off signal from +5 to +12 volts. The Power
Control Output will in turn provide a Power
+12 volt Output Signal with a current Control
Meter
up to 20mA. An additional connection Illumination
Control
is for controlling the illumination of
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:
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 Amplifier. The 300 watt power output will drive any high quality
Loudspeaker System to its ultimate performance. The
MC2301 reproduction is sonically transparent and absolutely accurate. The McIntosh Sound is “The Sound of the
Music Itself.”
Performance Features
• Power Output
The MC2301 is a Tube Power Amplifier with a capability of 300 watts into 2, 4 or 8 ohm speakers with less than
0.5% distortion.
• Full Balanced Unity Coupled Circuitry
The MC2301 is fully balanced from input to output. It consists of two matched Power Amplifiers operating in pushpull 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.
• Balanced and Unbalanced Input
Balanced connections guard against induced noise and allow long cable runs without compromising sound quality.
• 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.
• 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.
• 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 contamination. Output Tube Sockets include Air-Pipe cooling
at their bases.
• Special Power Supply
A regulated Power Supply, a very large core Power Transformer and large capacitors ensure stable noise free operation 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).
• Glass Front Panel and Super Mirror Chassis Finish
The famous McIntosh Illuminated Glass Front Panel and
the Stainless Steel Chassis with Super Mirror Finish ensure the pristine beauty of the MC2301 will be retained for
many years.
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Dimensions
Dimensions
The following dimensions can assist in determining the
best location for your MC2301. There is additional information on page 9 pertaining to installing the MC2301 into
cabinets.
17-3/4"
45.09cm
11"
Front View of the MC2301
27.94cm
12-5/16"
31.27cm
17-3/8"
44.15cm
Rear View of the MC2301
12-1/4"
31.11cm
21"
54.61cm
20"
1-5/8"
50.86cm
4.12cm
10-1/2"
3/16"
0.48cm
Side View of the MC2301
1-1/2"
3.81cm
8
15-3/4"
40.00cm
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1-3/4"
4.45cm
26.70cm
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Installation
Installation
The MC2301 can be placed upright on a table or shelf,
for clearance. Be sure to cut out a ventilation hole in the
standing on its four feet. It also can be custom installed in
mounting shelf according to the dimensions in the drawa piece of furniture or cabinet of your choice. The four feet
ing.
may be removed from the bottom of the MC2301 when it is
1
When the MC2301 is installed together with other McIntosh
custom installed as outlined below. The four feet together
Components, check clearances on all components before
with the mounting screws should be retained for possible
proceeding.
future use if the MC2301 is removed from the custom installation and used free
standing. The required
17-9/16"
panel cutout, ventilation
44.62cm
cutout and unit dimensions are shown.
Always provide adequate ventilation for
your MC2301. Cool
10 -13/16"
MC2301 Front Panel
operation ensures the
27.46cm
Custom Cabinet Cutout
longest possible operating life for any electronic instrument. Do
not install the MC2301
directly above a heat
generating component
such as a high powered
12"
Cabinet
amplifier. If all the com30.48cm
Cutout Opening for Custom Mounting
Front
ponents are installed in
Panel
a single cabinet, a quiet
running ventilation fan
Opening
can be a definite asset in
for Ventilation
maintaining all the system components at the
coolest possible operating temperature.
A custom cabinet instal- MC2301 Side View
in Custom Cabinet
lation should provide
the following minimum
Chassis
Spacers
spacing dimensions for
cool operation.
Cutout Opening for Ventilation
Allow at least 12 inches
(30.48cm) above the top,
Support
2"
Shelf
2 inches (5.08cm) below
5.08cm
the bottom and 4 inches
(10.16cm) on each side
of the Power Ampli17-1/2"
fier, so that airflow is
44.45cm
2-1/32"
not obstructed. Allow
MC2301 Bottom View
1.67cm
15-5/16"
14"
in Custom Cabinet
22 inches (55.88cm)
38.91cm
Cutout Opening
35.56cm
for Ventilation
depth behind the front
panel. Allow 1-5/8
Note: Center the cutout Horizontally on the unit.
inch (4.12cm) in front
For purposes of clarity, the above
illustration is not drawn to scale.
of the mounting panel1
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Notes
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Rear Panel Connections and Switch
INPUT MODE switch
selects between balanced
or unbalanced input
Main Fuse holder,
refer to information
on the back panel
of your MC2301 to
determine the correct fuse size and
rating
OUTPUT Connections
for 2 ohm Loudspeaker
OUTPUT Connections
for 4 ohm Loudspeaker
OUTPUT Connections
for 8 ohm Loudspeaker
Caution: The Loudspeaker
Negative Connections are
above chassis ground. Do not combine any connections together, ground them or connect with
another MC2301 or other Power Amplifier.
1
BALANCED INput1 / OUTput
for an audio cable from a Preamplifier output 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 McIntosh Component
Connect the MC2301
power cord to a live AC
outlet. Refer to the rear
panel to determine the
correct voltage
UNBALANCED INPUT
for an audio cable from a
Preamplifier or A/V Control Center audio output
BALANCED INPUT
for an audio cable
from a Preamplifier
or A/V Control Center audio output
This Balanced connector may be used as an Input ONLY when connected to a McIntosh C1000 Preamplifier. For all other connections use only as an Output.
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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 Loudspeaker Connections have been made. Failure
to observe this could result in Electric Shock.
For additional instruction on making Loudspeaker 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 the MC2301 POWER CONTROL IN.
2. Connect a cable from the Balanced Output of a McIntosh Preamplifier or Control Center to the MC2301
BALANCED INPUT. Place the INPUT MODE Switch
in the BALANCED Position.
Note: An optional hookup is to use an unbalanced cable
and place the INPUT MODE Switch in the UNBALANCED 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:
Loudspeaker Cable Distance vs Wire Gauge Guide
Loudspeaker
Impedance
25 feet
(7.62 meters)
or less
50 feet
(15.24 meters)
or less
100 feet
(30.48 meters)
or less
2 Ohms
12AWG
10AWG
8AWG
4 Ohms
14AWG
12AWG
10AWG
8 Ohms
16AWG
14AWG
12AWG
3. This McIntosh MC2301 Tube Power Amplifier is designed 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.
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.
5. Connect the Loudspeaker hookup cables from a single
Loudspeaker to the output terminals that match the impedance 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 connection.
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, carefully twist the
strands together
as tightly as posFigure 2
Figure 3
Figure 1
sible.
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
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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 Loudspeaker Connections have been made. Failure
to observe this could result in Electric Shock.
For additional instruction on making Loudspeaker 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 McIntosh Preamplifier or Control Center to the BALANCED
INPUT on the McIntosh MC2301 Power Amplifier.
4. Connect a cable from the BALANCED INPUT/OUTPUT 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.
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
Loudspeaker
Impedance
25 feet
(7.62 meters)
or less
50 feet
(15.24 meters)
or less
100 feet
(30.48 meters)
or less
2 Ohms
8AWG
12AWG
10AWG
4 Ohms
14AWG
12AWG
10AWG
8 Ohms
16AWG
14AWG
12AWG
5. This McIntosh MC2301 Tube Power Amplifier is designed 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.
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 impedance 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 connection.
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 insulation from the
cable ends, refer
Figure 2
Figure 3
Figure 1
to figures 1, 2 &
14
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How to Connect for Bi-Amp
McIntosh Preamplifier
McIntosh
Loudspeaker
Connect to
AC Outlet
McIntosh Power Amplifier Two
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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 Activation Indicator
METER Switch selects
the display modes of the
Power Output Meter and
Meter Illumination
16
POWER Switch Turns
AC Power On/Off, or
On/Remote
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How to Operate
How to Operate
Power On
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 operation, rotate the power switch to the
On or Off position as desired. Refer to
figure 8.
Note: There must be a power control
connection between the MC2301
and the McIntosh Control Center,
in order for the remote power
turn-on to function.
Figure 8
Meter Selection
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
meter will continue to indicate the
power output.
Figure 9
Note: When Power
Control Input of the MC2301 is connected to a McIntosh A/V Control Center or
Preamplifier with Remote Meter Illumination Control, the Meter Illumination
will automatically be remotely controlled (On/Off) with the METER Switch
set to the WATTS or HOLD position.
Watts- The meter responds to all the musical information 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.
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 approximately 6dB per minute.
Input Mode Switch
The Input Mode Switch, which is located on the Rear Panel
of the MC2301, allows you to select either the BAL (Balanced) or UNBAL (Unbalanced) Input. Refer to figure 11.
Standby/Protection Indicator
The MC2301 Sentry Monitor Tube Protection Circuitry provides protection to the
Power Amplifier in the event of an impedance mismatch1 between the MC2301 and
Figure 11
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 Output Tube should fail. During normal operation the Sentry
Monitor Tube Protection Circuitry has no effect on the
performance of the Power Amplifier.
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 waiting approximately one minute, place the POWER Switch
to the REMOTE or ON position.
1
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
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 Loudspeaker at low frequencies where the greatest amount of
power is required.
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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 created a tube power amplifier without compromise, using the
most advanced McIntosh circuit design concepts.
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 manufactured. The distortion limits for the MC2301 are no more
than 0.5% at rated power output for all frequencies from
20Hz to 20,000Hz. Typical performance at mid frequencies is less than 0.05%. The MC2301 can deliver the best
possible performance from any type of high quality loudspeaker system.
Creating a tube amplifier with this level of performance
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
the final design was accepted.
Top View of the MC2301
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Technical Description
MC2301 Design
The design philosophy incorporated in the MC2301 involved several different techniques, all based on sound scientific logic. Every stage of voltage amplification must be
as linear as possible prior to the use of negative feedback.
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-
Block Diagram of the
MC2301 Power Amplifier,
Protection Circuitry and
Power Supply
Figure 12
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Technical Description, con’t
feedback designs.
The fully Balanced Push-Pull design is used from input
to output. The resulting fully balanced configuration cancels many forms of audible distortion and greatly improves
the Signal-to-Noise ratio of the amplifier.
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 distortion, wider bandwidth and increased loudspeaker damping
factor. Refer to figure 13.
Figure 13
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
with optimum impedance points of two ohms, four ohms
and eight ohms. The unequaled expertise of McIntosh in
the design
and manufacturing
of transformers is
legendary
in the high
fidelity
industry.
Precision metal
film resistors and
low dielectric absorption film
capacitors
Figure 14
20
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.
Power Output Meter
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 electronically 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 human eye to
perceive its
position,
Figure 15
then drops.
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.
Sentry Monitor Protection Circuit
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
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Figure 16
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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
ensures safe operation of the amplifier under even the most
extreme operating conditions.
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 next power amplifier occurs at a later time. This helps
prevent power circuit overload that could trip circuit breakers or blow fuses, a very important feature in a high power
Home Theater System employing multiple MC2301 Power
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 Control 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
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Specifications
Specifications
Power Output
Minimum sine wave continuous average power output is:
300 watts into 2 ohm load
300 watts into 4 ohm load
300 watts into 8 ohm load
Output Load Impedance
2, 4 or 8 ohms
Power Requirements
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
Note: Refer to the rear panel of the MC2301 for the correct
voltage.
Rated Power Band
20Hz to 20,000Hz
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
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
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 combination 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
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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
1
1
2
3
2
Part Number
034105
034104
034439
034441
034440
1
0410900
Description
Shipping carton top
Shipping carton bottom
Foam Pad (top and bottom)
Foam Ring
Foam Inserts (for protecting
the Tubes during shipping)
Warning Sheet
4
4
400159
018445
10-32 x 3/4 inch screw
Feet
TUBE
COVERS
FOAM
INSERT
FOAM
INSERT
WARNING
SHEET
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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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