McIntosh MC2301 User Manual

Tube Power Amplifier

MC2301

Owner’s Manual

McIntosh Laboratory, Inc. 2 Chambers Street Binghamton, New York 13903-2699 Phone: [phone] FAX: [phone]

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.

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.

2

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

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 re-

moved 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.

Failure to do so has the poten-

tial of a Fire Hazard, resulting
in damage to the MC2301 and
the surrounding environment.

Follow the instructions below

for removal of the packing foam
before connecting the AC Power
Supply Cord to the MC2301.

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.

Figure 2

Tube Covers

Remove Foam
Inserts located
under the Tube
Covers and the
Warning Sheet

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.

REFER TO PAGE 3 IN THE
MC2301 OWNER’S MANUAL
FOR INSTRUCTIONS.

Figure 1

Chassis
screws

Tube Cover

4

Figure 3

Figure 4

Unpacking the MC2301 and Ventilation

Figure 5

Figure 6

Foam Insert

Figure 8

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

Tube Cover

Figure 7

Cool Air

Figure 9

Chassis
screws

5

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.

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: ___________________________________

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: [phone]
Fax: [phone]

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:

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 ......................................................

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

General Information

Caution: The MC2301 Amplifier weight is 116 pounds (52.6

kilograms). It requires two or more persons to safely
handle when moving the amplif ier.

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.

7

McIntosh Laboratory, Inc.
2 Chambers Street
Binghamton, New York 13903
Phone: [phone]
Fax: [phone]

Copyright 2008 © by McIntosh Laboratory, Inc.

6

Power
Control

Meter
Illumination
Control

Ground

PIN 2PIN 1

PIN 3

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
diagram for connection:
PIN 1: Shield/Ground
PIN 2: + Output
PIN 3: - Output

Power Control Connector

The MC2301 Power Control Input receives an On/Off sig

­nal from +5 to +12 volts. The Power
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
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 capabil
ity 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 con
sists 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 al
low 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 con
tamination. Output Tube Sockets include Air-Pipe cooling
at their bases.

• Special Power Supply

A regulated Power Supply, a very large core Power Trans
former 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 en
sure the pristine beauty of the MC2301 will be retained for
many years.

-

-

-

-

-

7

Dimensions

17-3/4"

45.09cm

11"

27.94cm

12-5/16"

31.27cm

20"

50.86cm

21"

54.61cm

3/16"

0.48cm

10-1/2"

26.70cm

15-3/4"

40.00cm

1-3/4"

4.45cm

1-1/2"

3.81cm

12-1/4"

31.11cm

17-3/8"

44.15cm

1-5/8"

4.12cm

Front View of the MC2301

Rear View of the MC2301

Side View of the MC2301

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.

Dimensions

8

Installation

10 -13/16"

27.46cm

17-9/16"

44.62cm

12"

30.48cm

17-1/2"

44.45cm

14"

35.56cm

15-5/16"

38.91cm

2-1/32"

1.67cm

Cutout Opening
for Ventilation

Cutout Opening for Ventilation

Support
Shelf

Cabinet
Front
Panel

Chassis
Spacers

Cutout Opening for Custom Mounting

Opening
for Ventilation

MC2301 Front Panel
Custom Cabinet Cutout

MC2301 Side View
in Custom Cabinet

MC2301 Bottom View
in Custom Cabinet

2"

5.08cm

Note: Center the cutout Horizontally on the unit.
For purposes of clarity, the above
illustration is not drawn to scale.

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 in­stallation and used free
standing. The required
panel cutout, ventilation
cutout and unit dimen­sions are shown.
Always provide ad­equate ventilation for
your MC2301. Cool
operation ensures the
longest possible operat­ing life for any elec­tronic instrument. Do
not install the MC2301
directly above a heat
generating component
such as a high powered
amplifier. If all the com­ponents are installed in
a single cabinet, a quiet
running ventilation fan
can be a definite asset in
maintaining all the sys­tem components at the
coolest possible operat­ing temperature.
A custom cabinet instal­lation should provide
the following minimum
spacing dimensions for
cool operation.
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 Ampli­fier, 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 panel

1

for clearance. Be sure to cut out a ventilation hole in the
mounting shelf according to the dimensions in the draw­ing.

1

When the MC2301 is installed together with other McIntosh

Components, check clearances on all components before
proceeding.

Installation

9

Notes

10

Rear Panel Connections and Switch

Connect the MC2301
power cord to a live AC
outlet. Refer to the rear
panel to determine the
correct voltage

Main Fuse holder,
refer to information
on the back panel
of your MC2301 to
determine the cor­rect fuse size and
rating

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

INPUT MODE switch
selects between balanced
or unbalanced input

BALANCED INput

1

/ OUTput
for an audio cable from a Pre­amplifier

output or to connect an
audio cable on to the next Power
Amplifier 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-

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

This Balanced connector may be used as an Input ONLY when connected to a McIntosh C1000 Preamplifier. For all other connec-

UNBALANCED INPUT
for an audio cable from a
Preamplifier or A/V Con­trol Center audio output

ter audio output

tions use only as an Output.

11

How to Connect

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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

2 Ohms

4 Ohms

8 Ohms

25 feet

(7.62 meters)

or less

12AWG 10AWG 8AWG

14AWG 12AWG 10AWG

16AWG 14AWG 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.

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 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.

50 feet

(15.24 meters)

or less

100 feet

(30.4 8 meters)

or less

-

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 fig­ures 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.

12

McIntosh Preamplifier

How to Connect

Connect to
AC Outlet

McIntosh
Loudspeaker

13

How to Connect for Bi-Amp

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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

2 Ohms

4 Ohms

8 Ohms

25 feet

(7.62 meters)

or less

12AWG 10AWG 8AWG

14AWG 12AWG 10AWG

16AWG 14AWG 12AWG

5. This McIntosh MC2301 Tube Power Amplifier is de

50 feet

(15.24 meters)

or less

100 feet

(30.4 8 meters)

or less

­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.

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
to figures 1, 2 &

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 fig­ures 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.

14

McIntosh Preamplifier

How to Connect for Bi-Amp

Connect to
AC Outlet

McIntosh
Loudspeaker

McIntosh Power Amplifier Two

15

Meter indicates the Power
Output of the Amplifier

Front Panel Displays and Controls

Standby Power On and Sentry
Monitor Tube Protection Activa­tion Indicator

16

METER Switch selects
the display modes of the
Power Output Meter and
Meter Illumination

POWER Switch Turns
AC Power On/Off, or
On/Remote

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 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

connection between the MC2301
and the McIntosh Control Center,
in order for the remote power
turn-on to function.

-

Figure 8

How to Operate

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 (Bal
anced) or UNBAL (Unbalanced) Input. Refer to figure 11.

-

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.

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 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.

Figure 9

Standby/Protection Indicator

The MC2301 Sentry Monitor Tube Protec

­tion 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 f lowing
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.

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

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 Loud­speaker at low frequencies where the greatest amount of
power is required.

17

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.

18

Top View of the MC2301

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

19

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 manu

­facturing
of trans­formers is
legendary
in the high
fidelity
industry.

Preci­sion metal
film resis­tors and
low dielec­tric absorp­tion film
capacitors

Figure 14

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 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 hu­man eye to
perceive its
position,
then drops.

Figure 15

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

Figure 16

-

20

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 f lowing
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

the next power amplifier occurs at a later time. This helps
prevent power circuit overload that could trip circuit break
ers or blow fuses, a very important feature in a high power
Home Theater System employing multiple MC2301 Power

-

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

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

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

Input Sensitivity (for rated output)

1.7 Volt Unbalanced

3.4 Volt Balanced

Signal To Noise Ratio (A-Weighted)

117dB below rated output

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.

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

Shipping Carton Dimensions

Width is 31 inches (78.74cm)
Depth is 28 inches (71.12cm)
Height is 17-1/4 inches (43.82cm)

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

Packing Instructions

WARNING
SHEET

FOAM
INSERT

FOAM
INSERT

TUBE
COVERS

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 034105 Shipping carton top
1 034104 Shipping carton bottom
2 034439 Foam Pad (top and bottom)
3 034441 Foam Ring
2 034440 Foam Inserts (for protecting
the Tubes during shipping)
1 0410900 Warning Sheet

4 400159 10-32 x 3/4 inch screw
4 018445 Feet

23

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