McIntosh MC462 operation manual

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

MC462

Quad Balanced

Power Amplier

Owner’s Manual

Important Safety Information is supplied in a separate document “Important Additional Operation Information Guide”

Thank You

Your decision to own this McIntosh MC462 Stereo
Power Amplifier with Quad Balanced Circuitry 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:

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

Table of Contents

Safety Instructions ..................................................... 2

(Separate Sheet) ................... Important Additional

Operation Information Guide

Thank You and Please Take a Moment .......................2

Technical Assistance and Customer Service .............. 2

Table of Contents ........................................................ 2

General Information ................................................... 2

Connector and Cable Information ..............................3

Introduction .................................................................3

Performance Features .................................................3

Dimensions .................................................................5

Installation ..................................................................6

Rear Panel Connections and Switch ........................... 7

Output Terminals and How to Connect .................. 8-9

Output Terminals and How to Connect

for Bi-Amp ......................................................... 10 -11

Front Panel Displays and Controls ............................ 12

How to Operate ......................................................... 13

Technical Description .......................................... 14 -17

Specifications ............................................................ 18

Packing Instruction ................................................... 19

General Information

1. For additional connection information, refer to the
owner’s manual(s) for any component(s) connected
to the MC462.

2. The MC462 mutes the speaker output for approxi­mately two seconds when first turned on.

3. For the best performance and safety it is important
to always match the impedance of the Loudspeaker
to the Power Amplifier connections. Refer to “How
to Connect” pages 7 thru 10.

Note: The impedance of a Loudspeaker actually var-

ies 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. Contact the Loudspeaker Manufac­turer for additional information about the actual
impedance of the Loudspeaker before connecting

it to the McIntosh MC462.

4. In the event the MC462 over heats, due to improper
ventilation and/or high ambient temperature, the
protection circuits will activate. The Front Panel
Power Guard LED will continuously indicate ON
and the audio will be muted. When the MC462 has
returned to a safe operating temperature, normal
operation will resume.

5. When discarding the unit, comply with local rules
or regulations. Batteries should never be
thrown away or incinerated but disposed
of in accordance with the local regulations
concerning battery disposal.

6. For additional information on the MC462 and
other McIntosh Products please visit the McIntosh
Website at www.mcintoshlabs.com.

Copyright 2018 © by McIntosh Laboratory, Inc.

2

Cable 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 MC462. Refer
to the diagram for connection:

IN

OUT

PIN 1: Shield/Ground
PIN 2: + Input/Output

PIN 1

PIN 3: - Input/Output

PIN 2 PIN 1

PIN 3

PIN 3

PIN 2

Power Control Connector

The MC462 Power Control Input receives an On/Off
signal from +5 to +12 volts. The Power Control Output
will in turn provide a +12 volt
Output Signal with a total cur­rent up to 50mA. An additional
connection is for controlling
the illumination of the MC462

Trigger
Control

Meter
Illumination
Control

Ground

Power Output Meters. The 1/8
inch stereo mini phone plug connects to a McIntosh
Preamplifier or A/V Control Center Power Control
Output.

Output Terminal Connector

When cables with spade lugs are used
for Loudspeaker Connection, the spade
lugs need an opening of at least 3/10 inch
(7. 6m m).

3/10 of an inch
(7.6millimeters)

Introduction

Now you can take advantage of traditional McIntosh
standards of excellence in the MC462 Stereo Power
Amplifier with Quad Balanced Circuitry. The 450
watts high current output per channel will drive any
high quality Loudspeakers. The MC462 reproduction
is sonically transparent and absolutely accurate. The
McIntosh Sound is “The Sound of the Music Itself”.

Performance Features

• Power Output

The MC462 is a Power Amplifier with a capability
of 450 watts per channel into 2, 4 or 8 ohm speakers
with less than 0.005% distortion. The Power Amplifier
Circuitry uses Thermal Trak1 Output Transistors for
lower distortion and cool operation.

• Quad Balanced Circuitry

The MC462 is fully balanced from input to output. It
consists of two matched power amplifiers operating
in push-pull with their outputs combined in a McIn­tosh Autoformer. The Quad Balanced configuration
cancels virtually all distortion.

• Patented Autoformer

McIntosh designed and manufactured Output Auto­formers provide an ideal match between the amplifier
output stages and speaker loads of 2, 4 and 8 ohms.
The Autoformers also provide perfect DC protection
for your valuable loudspeakers.

• Balanced and Unbalanced Inputs

Balanced connections guard against induced noise and
allow long cable runs without compromising sound
qual ity.

• Power Guard

The patented McIntosh Power Guard circuit prevents
the amplifier from being over driven into clipping,
with its harsh distorted sound that can also damage
your valuable loudspeaker.

• Sentry Monitor and Thermal Protection

McIntosh Sentry Monitor power output stage protec­tion circuits ensure the MC462 will have a long and

1

ThermalTrak™ and ON Semiconductor are trademarks of Semi-

conductor Components Industries, LLC

trouble free operating life. Built-in Thermal Protection
Circuits guard against overheating.

• Special Power Supply

A very large Power Transformer and Large Capaci­tors ensure stable noise free operation even though the
power line varies.

• Illuminated Power Meters

The Illuminated Power Output Watt Meters on the
MC462 are peak responding, and indicate the true
power output of the amplifier. The Peak Watt Hold
Mode allows the meters to temporarily stay at the
highest power output and then slowly decay. The Front
Panel Meter Illumination may be switched Off at any
time.

• McIntosh Custom Binding Posts

McIntosh patent pending gold plated output terminals
deliver high current output. They accept large diam­eter wire and spade lugs. Banana plugs may also be
used only in the United States and Canada.

• Glass Front Panel and Super Mirror Chassis
Finish

The famous McIntosh Illuminated Glass Front Panel
uses long life Light Emitting Diodes (LEDs) and
the Stainless Steel Chassis with Super Mirror Fin­ish ensures the pristine beauty of the MC462 will be
retained for many years.

3

Dimensions

29.9cm

The following dimensions can assist in determining
the best location for your MC462.

Front View of the MC462

17-1/2"

44.5cm

Dimensions

Rear View of the MC462

16-13/16"

42.7cm

DISABLED

8-7/8"

22.5cm

9-7/16"

24.0cm

2-1/4"

5.7cm

Side View of the MC462

20-1/2"

52.1cm

16-5/8"

42.2cm

12-1/2"

31.8cm

3/16"

0.5cm

8-3/8"

21.3cm

2-3/16"

5.6cm

11-3/4"

4

Installation

Installation

The MC462 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 MC462 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
MC462 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 MC462.
Cool operation ensures the longest possible operating
life for any electronic instrument. Do not install the
MC462 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 6 inches (15.24cm) above the top, 2
inches (5.08cm) below the bottom, 3 inches (7.62cm)
behind the rear panel and 2 inches (5.08cm) on each
side of the Power Amplifier, so that airflow is not
obstructed. Allow 2-1/2 inches (6.35 cm) in front of
the mounting

a ventilation hole in the mounting shelf according
to the dimensions in the drawing.

1

When the MC462 is installed together with other McIn-

tosh Components, check clearances on all components
before proceeding.

1

panel for clearance. Be sure to cut out

MC462 Front Panel
Custom Cabinet Cutout

Cabinet
Front
Panel

Opening
for Ventilation

MC462 Side View
in Custom Cabinet

MC462 Bottom View
in Custom Cabinet

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

Cabinet Front Panel

Support
Shelf

17"

43.18cm

Opening for Ventilation

Cutout Opening for Custom Mounting

6"

15.24cm

Cutout Opening for Ventilation

2-1/2"

6.35cm

12-3/4"

32.38cm

16"

Cutout Opening
for Ventilation

40.64cm

14-11/16"

37.30cm

Chassis
Spacers

5

Rear Panel Connections and Switch

Balanced OUTputs (LEFT and
RIGHT Channels) for an audio
cable to the next Power Ampli­fier Input

INPUT MODE switch se­lects between BALANCED
or UNBALANCED Inputs

Unbalanced INput (RIGHT Channel) for an
audio cable from a Preamplifier or A/V Con­trol Center audio output.
Unbalanced OUTput (RIGHT Channel) for an
audio cable to the next Power Amplifier Input

Balanced INputs (LEFT
and RIGHT Channels) for
audio cables from a Pre­amplifier or A/V Control
Center audio output

DISABLED

Unbalanced INput (LEFT Channel) for an au­dio cable from a Preamplifier or A/V Control
Center audio output.
Unbalanced OUTput (LEFT Channel) for an
audio cable to the next Power Amplifier Input

POWER CONTROL IN
receives turn On/Off
signals from a McIntosh
component.
POWER CONTROL OUT
1 and 2 send turn On/Off
signals to the next McIn­tosh Component

RIGHT OUTPUTS
Connection for a 2
ohm Loudspeaker

RIGHT OUTPUTS
Connection for an 8
ohm Loudspeaker

Fuse holder, refer to
information on the rear
panel of your MC462 to

LEFT OUTPUTS
Connection for an 8
ohm Loudspeaker

LEFT OUTPUTS
Connections for a 2

ohm Loudspeaker
determine the correct
fuse size and rating

RIGHT OUTPUTS
Connection for a 4
ohm Loudspeaker

Connect the MC462 power
cord to a live AC outlet. Refer
to the rear panel to determine
the correct voltage

AUTO OFF Mode
Switch selects be­tween ENABLED
or DISABLED

LEFT OUTPUTS
Connection for a 4
ohm Loudspeaker

Caution: The Loudspeaker Negative Connections are above chassis ground. Do not combine any connections together, ground them or connect with another MC462.

6

Output Terminals

When connecting the Loudspeaker Hookup Cables to
the MC462 Power Amplifier Output Terminals please
follow the steps below:

1. Rotate the top of the Output Terminal Post coun­terclockwise until an opening

appears. Refer to gures A and

B.

2. Insert the Loudspeaker hookup
cable into the Output Terminal
Post opening or the cable spade
lug around the center post of

Figu re A

Opening

Figu re B

the Output Terminal. Refer to

gure C.

3. Rotate the top of the Output
Terminal Post clockwise until it

is nger tight. Refer to gure D.

4. Place the supplied McIntosh
Wrench over the top of the Out-

Figu re C Figu re D

put Terminal and rotate it one
quarter of a turn (90° ) to secure
the Loudspeaker Cable Connec­tion. Do not over tighten. Refer

to gure E.

Figu re E

How to Connect

Caution: Do not connect the AC Power Cord to the

MC462 Rear Panel until after the Loudspeaker
Connections are made and the protective Termi­nal Connections Covers are installed. Failure to
observe this could result in Electric Shock.

The connection instructions below, together with the
MC462 Connection Diagram located on the separate
folded sheet “Mc1A”, is an example of a typical audio
system. Your system may vary from this, however the
actual components would be connected in a similar
manner. For additional information refer to “Connec­tor and Cable Information” on page 3.

1. For Remote Power Control, connect a power control
cable from the Audio Preamplifier or A/V Con­trol Center Power Control Output 1 (Trig 1) to the
MC462 POWER CONTROL IN.

Notes: 1. When a Power Control Cable is connected

between the MC462 and Preamplifier (or
A/V Control Center), the AUTO OFF Fea­ture is bypassed. Refer to page 13.

2. When the MC462 has Loudspeakers con­nected to it with a Power Control Input,
connect the MC462 Power Control Out 1

and Out 2 to the Loudspeakers.

2. Connect XLR cables from the Balanced Output 1
(L&R) of an Audio Preamplifier or A/V Control
Center to the MC462 Balanced INput (RIGHT and
LEFT). Place the INPUT MODE Switch in the
BALANCED Position.

Note: An optional hookup is to use unbalanced

cables and place the INPUT MODE Switch in
the UNBALANCED Position.

Remove Screws

DISABLED

Figu re 1

Remove Screws

3. Using a suitable tool remove the four screws from
the MC462 Rear Panel and temporarily place them
in a safe place. Refer to figure 1.

This McIntosh MC462 Stereo Power Amplifier with
Quad Balanced Circuity is designed for Loudspeak­ers with an impedance of 2 ohms, 4 ohms or 8 ohms.

Output Terminals and How to Connect

Connect a single Loudspeaker only to the Right and
Left Output Terminals.

When connecting Loudspeakers to the MC462 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

4. Prepare the Loudspeaker Hookup Cable for attach­ment to the MC462 Power Amplifier:

Figure 2

Bare wire cable ends:
Carefully remove sufficient insulation from the
cable ends, refer to figures 2, 3 & 4. If the cable
is stranded, carefully twist the strands together
as tightly as possible.

Notes: 1. If desired, the twisted ends can be tinned

with solder to keep the strands together.

2. The prepared bare wire cable ends may be
inserted into spade lug connectors.

3. Banana plugs are for use in the United
States and Canada only.

50 feet

(15.24 me ter s)

or less

Figure 3 Figure 4

100 fe et

(30. 48 meters)

or less

7

Output Terminals and How to Connect

Figure H

Banana Plugs are for use in the United States and
Canada only:

5. Locate the Terminal Connection Covers from the
inside of the MC462 shipping carton. Insert the
just prepared Loudspeaker hookup cables thru the
cover openings, one cover for each channel. Refer
to figure 5.

Cover Openings

DISABLED

Cover Screws Cover Screws

Figure 5 (Inside USA and Canada)

Cover Openings

6. Attach the previously prepared bare wire cable ends

into the banana plugs and secure the
connections. Refer to figure F.

7. Rotate the top of the Output Terminal

Post clockwise until it is nger tight.

Figure F

Refer to gure G. Then using the Mc­Intosh Wrench, rotate the top of the
Output Terminal one quarter of a turn
(90° ). Do not over tighten. Refer to

gure E.

8. Referring to figure H, connect the

Figu re G

Loudspeaker hookup
cables with banana plugs
into the hole at the top
of the terminal to the
MC462 Negative Out-

Figure H

put Terminal and Posi-

tive Output Terminal indentified as 2Ω (ohms),

4Ω (ohms) or 8Ω (ohms) connection to match the

impedance of the Loudspeaker, being careful to
observe the correct polarities.

Note: The illustration in figure 5 is connections for

8Ω (ohms) Loudspeakers.

If the Loudspeaker’s impedance is in-between
the available connections, use the nearest lower
impedance connection. Refer to “General Informa­tion” Note 4 on page 2 for additional information.

WARNING: Loudspeaker terminals are hazard-

ous live and present a risk of electric
shock. For additional instruction on
making Loudspeaker Connections con­tact your McIntosh Dealer or McIn­tosh Technical Support.

9. Attach the Terminal Connection Covers to the
MC462 Rear Panel with the previously removed
Screws. Refer to figure 5.

10. Connect the MC462 Power Cord to an active AC
outlet.

Spade Lug or Wire Connections:

11. Locate the Terminal Connections Covers from the
inside of the MC462 shipping carton. Insert the
just prepared Loudspeaker hookup cables thru the
cover openings, one cover for each channel. Refer
to figure 6.

Cover Openings

DISABLED

Cover Screws Cover Screws

Figure 6 (Outside USA and Canada)

Cover Openings

12. Connect the Loudspeaker hookup cables to the
MC462 Negative Output Terminal and Positive

Output Terminal indentified as 2Ω (ohms), 4Ω
(ohms) or 8Ω (ohms) connection to match the

impedance of the Loudspeaker, being careful to
observe the correct polarities. 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 terminals so the lugs or wire cannot slip out.
Refer to fgures 7 and 8.

Figure 7

Note: The illustration in figure 6 is connections for

8Ω (ohms) Loudspeakers.

Figure 8

If the Loudspeaker’s impedance is in-between
the available connections, use the nearest lower
impedance connection. Refer to “General Informa­tion” Note 3 on page 2 for additional information.

WARNING: Loudspeaker terminals are hazard-

ous live and present a risk of electric
shock. For additional instruction on
making Loudspeaker Connections con­tact your McIntosh Dealer or McIn­tosh Technical Support.

13. Attach the Terminal Connections Covers to the

MC462 Rear Panel with the previously removed
Screws. Refer to figure 6.

14. Connect the MC462 power cord to an active AC
outlet.

8

Output Terminals

When connecting the Loudspeaker Hookup Cables to
the MC462 Power Amplifier Output Terminals please
follow the steps below:

1. Rotate the top of the Output Terminal Post coun­terclockwise until an opening

appears. Refer to gures A and

B.

2. Insert the Loudspeaker hookup
cable into the Output Terminal
Post opening or the cable spade
lug around the center post of

Figu re A

Opening

Figu re B

the Output Terminal. Refer to

gure C.

3. Rotate the top of the Output
Terminal Post clockwise until it

is nger tight. Refer to gure D.

4. Place the supplied McIntosh
Wrench over the top of the Out-

Figu re C Figu re D

put Terminal and rotate it one
quarter of a turn (90° ) to secure
the Loudspeaker Cable Connec­tion. Do not over tighten. Refer

to gure E.

Figu re E

How to Connect for Bi-Amp

Caution: Do not connect the AC Power Cord to the

MC462 Rear Panel until after the Loudspeaker
Connections are made and the protective Termi­nal Connections Covers are installed. Failure to
observe this could result in Electric Shock.

The connection instructions below, together with the
MC462 Connection Diagram located on the separate
folded sheet “Mc1B”, is an example of a typical audio
system. Your system may vary from this, however the
actual components would be connected in a similar
manner. For additional information refer to “Connec­tor and Cable Information” on page 3.

Output Terminals and How to Connect for Bi-Amp

1. For Remote Power Control, connect a power control
cable from the Audio Preamplifier or A/V Con­trol Center Power Control Output 1 to the MC462
POWER CONTROL IN Amplifier One.

Note: When a Power Control Cable is connected be-

tween the MC462 (Power Amplifier 1) and Pre­amplifier (or A/V Control Center), the AUTO
OFF Feature is bypassed. Refer to page 13.

2. Connect a power control cable from Amplifier One
Power Control OUTput 1 to the MC462 POWER
CONTROL IN Amplifier Two.

Note: When the MC462 (Power Amplifier 2) has

Loudspeakers connected to it with a Power
Control Input, then connect the the MC462
Power Control Out 1 and Out 2 to the

Loudspeakers.

3. Connect XLR cables from the Balanced Output 1
(L&R) of an Audio Preamplifier or A/V Control
Center to the MC462 (Power Amplifier 1) Bal­anced INput (RIGHT and LEFT). Place the INPUT
MODE Switch in the BALANCED Position.

Note: An optional hookup is to use unbalanced

cables and place the INPUT MODE Switch in
the UNBALANCED Position.

4. Connect XLR cables from the MC462 (Power
Amplifier 1) Audio Balanced OUTput (LEFT and
RIGHT) to the MC462 (Power Amplifier 2) Bal­anced INput (RIGHT and LEFT). Place the INPUT
MODE Switch in the BALANCED Position.

5. Using a suitable tool remove the four screws from
the MC462 Rear Panel and temporarily place them
in a safe place. Refer to figure 1.

These McIntosh MC462 Stereo Power Amplifiers with
Quad Balanced Circuitry are designed for Loudspeak­ers with an impedance of 2 ohms, 4 ohms or 8 ohms.
Connect a single Loudspeaker only to the Right and
Left Output Terminals.

Remove Screws

DISABLED

Figu re 1

Remove Screws

When connecting Loudspeakers to the MC462 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

50 feet

(15.24 me ter s)

or less

100 fe et

(30. 48 meters)

or less

6. Prepare the Loudspeaker Hookup Cable for attach­ment to the MC462 Power Amplifier:

Bare wire cable ends:
Carefully remove sufficient insulation from the
cable ends, refer to figures 2, 3 & 4. If the cable
is stranded, carefully twist the strands together
as tightly as possible.

Figure 2

Notes: 1. If desired, the twisted ends can be tinned

with solder to keep the strands together.

Figure 3 Figure 4

9

2. The prepared bare wire cable ends may be

Figure H

inserted into spade lug connectors for use
outside the United States and Canada only.

3. Banana plugs are for use in the United
States and Canada only.

Banana Plugs are for use in the United States and
Canada only:

7. Locate the Terminal Connections Covers from the
inside of the MC462 shipping carton. Insert the
just prepared Loudspeaker hookup cables thru the
cover openings, one cover for each channel. Refer
to figure 5.

Cover Openings

DISABLED

Cover Screws

Figure 5 (Inside USA and Canada)

Cover Openings

Cover Screws

8. Attach the previously prepared bare wire cable
ends into the banana plugs and secure the connec­tions. Refer to figure F.

9. Rotate the top of the Output Terminal

Post clockwise until it is nger tight.
Refer to gure G. Then using the Mc-

Figure F

Intosh Wrench, rotate the top of the
Output Terminal one quarter of a turn
(90° ). Do not over tighten. Refer to

gure E.

Figu re G

10. Referring to figure H,
connect the Loudspeaker
hookup cables with ba­nana plugs into the hole

Figure H

at the top of the terminal
to the MC462 Negative Output Terminal and Posi-

tive Output Terminal indentified as 2Ω (ohms),
4Ω (ohms) or 8Ω (ohms) connection to match the

impedance of the Loudspeaker, being careful to
observe the correct polarities.

Note: The illustration in figure 5 is connections for

8Ω (ohms) Loudspeakers.

If the Loudspeaker’s impedance is in-between the
available connections, use the nearest lower imped­ance connection. Refer to “General Information”
Note 3 on page 2 for additional information.

WARNING: Loudspeaker terminals are hazard-

ous live and present a risk of electric
shock. For additional instruction on
making Loudspeaker Connections con­tact your McIntosh Dealer or McIn­tosh Technical Support.

11. Attach the Terminal Connections Covers to the
MC462 Rear Panel with the previously removed
Screws. Refer to figure 5.

12. Connect the MC462 power cord to an active AC
outlet.

Spade Lug or Wire Connections:

13. Locate the Terminal Connection Covers from the
inside of the MC462 shipping carton. Insert the
just prepared Loudspeaker hookup cables thru the
cover openings, one cover for each channel. Refer
to figure 6.

Cover Openings

DISABLED

Cover Screws Cover Screws

Figure 6 (Outside USA and Canada)

Cover Openings

14. Connect the Loudspeaker hookup cables to the
MC462 Negative Output Terminal and Positive

Output Terminal indentified as 2Ω (ohms), 4Ω
(ohms) or 8Ω (ohms) connection to match the

impedance of the Loudspeaker, being careful to
observe the correct polarities. 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 terminals so the lugs or wire cannot slip out.
Refer to figures 7 and 8.

Figure 7

Note: The illustration in figure 6 is connections for

8Ω (ohms) Loudspeakers.

Figure 8

If the Loudspeaker’s impedance is in-between
the available connections, use the nearest lower
impedance connection. Refer to “General Informa­tion” Note 3 on page 2 for additional information.

10

WARNING: Loudspeaker terminals are hazard-

ous live and present a risk of electric
shock. For additional instruction on
making Loudspeaker Connections con­tact your McIntosh Dealer or McIn­tosh Technical Support.

15. Attach the Terminal Connections Covers to the
MC462 Rear Panel with the previously removed
Screws. Refer to figure 6.

16. Connect the MC462 power cord to an active AC
outlet.

Output Terminals and How to Connect for Bi-Amp

11

Front Panel Displays and Controls

Meter indicates the
Left Channel Output
of the amplifier

LED indicates when the Left
Channel Amplifier POWER
GUARD circuit activates

Standby Power
On Indicator

LED indicates when the Right
Channel Amplifier POWER
GUARD circuit activates

Meter indicates the
Right Channel Output
of the amplifier

12

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

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

How to Operate

DISABLED

How to Operate

Power On

To have the MC462 automatically turn On or Off
when a Preamplifier or A/V 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 9.

Note: There must be a power con-

trol connection between the
MC462 and the Audio Pre­amplifier (or A/V Control Center), in order for the
remote power turn-on to function.

Figure 9

Meter Selection

Rotate the meter mode switch to select the meter op­eration mode you desire. Refer to
figures 10 and 11.

Lights Off - Meter lights are

turned off and the
meter will contin­ue to indicate the

Fig u re 10

power output.

Note: When Power Control Input of the

MC462 is connected to an Audio
Preamplifier or A/V Control Center
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 meters respond to all the musi-

cal information being produced by the
amplifier. They indicate to an accuracy
of at least 95% of the power output with
only a single cycle of a 2000Hz tone
burst.

Fi g u re 11

Hold - The meter pointer is locked to the high-

est power peak in a sequence of peaks.
It is electronically held to this power
level until a higher power peak passes
through the 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.

Note: The MC462 Power Output Meter

indicates the actual power delivered
to the loudspeakers by responding
to the combination of current and
voltage output.

Input Mode Switch

The Input Mode Switch, which is located on the Rear
Panel of the MC462, allows
selection of either the Bal­anced or Unbalanced Input.
Refer to figure 12.

Figure 12

Auto Off Switch

The MC462 incorporates Power Save Circuitry to
automatically place the MC462 into the power saving
Standby Mode approximately 30 minutes after there
has been an absence of an audio input signal.

When there is a Power Control Connection be­tween the MC462 and a Preamplifier with Power Save
Circuitry, the AUTO OFF Switch is bypassed (located
on the Rear Panel of the MC462). Refer to figure 13.

In the event there is no
Power Control Connection
and the Power Save Circuitry
is activating inappropriately
relative to your specific use of

DISABLED

Figure 13

the MC462, place the AUTO
OFF Switch in the DISABLE position.

Note: If the Power Save Circuitry has switched Power

to the MC462 OFF, place the POWER in the OFF
Position and then in the ON position to reset the
circuitry.

13

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 Power Amplifier without compro­mise, using the most advanced McIntosh circuit design
concepts.

Figure 13

The MC462 has a continuous average power output
rating of 450 watts and with a peak output current of
75 amperes per channel; making this one of the most
advanced amplifiers available today. The distortion
limits for the MC462 are no more than 0.005% at
rated power output for all frequencies from 20Hz to

20,000Hz. Typical performance
at mid frequencies is less than

0.002%. The true distortion
readings on the MC462 are so
low, it takes special measuring
techniques to make accurate
readings. The MC462 can deliver
the best possible performance
from any type of high quality
loudspeaker system. Refer to
figure 13.

Creating an 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.

Design Philosophy

The design philosophy incor­porated in the MC462 involved
several different techniques, all
based on sound scientific logic.
Every stage of voltage or cur­rent 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 extremely low distortion performance expected
from a McIntosh amplifier. The typical McIntosh
owner would never accept the approximately 100
times higher distortion of many non-feedback designs.

Double Balanced Push-Pull design is used from
input to output. Each half of the amplifier contains
complimentary balanced circuitry. The resulting Quad
Balanced configuration cancels even order distortion.
Refer to figure 14.

All transistors are selected to have nearly constant
current gain over the entire current range they must
cover. Output transistors in particular, have matched
uniform current gain, high current bandwidth prod­uct and large active region safe operating area. These
Power Transistors are the very latest in semiconductor
technology and incorporate a new design known as
ThermalTrak™. Refer to figure 15. This allows for the
instantaneous and accurate monitoring of the Power
Transistor Temperature. The MC462
Power Output Circuitry has a specially
designed bias circuit to take full advan­tage of the ThermalTrak™ Power Transis­tors and thus precisely controls the power
amplifier operation over a wide range
of music conditions with the benefits of
lower distortion and cooler operation.
Precision metal film resistors and low

Fig ure 15

dielectric absorption film capacitors are
used in all critical circuit locations.

The output signals of the two balanced circuits
are coupled together in the unique McIntosh MC462
Output Autoformer. 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

14

Technical Description

UNBALANCED

INPUT

UNBALANCED

OUTPUT

BALANCED

INPUT

BALANCED

OUTPUT

expertise of McIntosh in the design and
manufacturing of autoformers is legend­ary in the high fidelity industry.

The high efficiency circuit design of
the MC462 contributes to low operat­ing temperatures. More than 2800
square inches of heat sink area keep the
MC462 operating safely with convec­tion cooling. No fans are needed. Refer
to figure 16.

than one loudspeak­er connected in
parallel, the load to
the power amplifier
may drop to two
ohms or even less.
A power amplifier
connected to a load
that is lower than
optimum, causes
more output cur­rent to flow, which
results in extra heat
being generated in
the power output
stage. This increase
in temperature will

Figure 16

Autoformers

All solid state power amplifier output
circuits work best into what is called an
optimum load. This optimum load may
vary considerably from what a loud­speaker requires. In the case of more

result in a reduced

Figure 17

ThermalTrak
DC BIAS

life expectancy for the amplifier.

The special Balanced Winding

Autoformer creates an ideal match

+

AMP

INPUT MODE

SWITCH

-

AMP

+

-

+

-

POWER GUARD

ATTENUATOR

BALANCED

THERMAL
SENSORS

MUTE

AMP

ThermalTrak
DC BIAS

Block Diagram

OUTPUT

of the

Power Amplifier

(one channel shown)

between the power amplifier output
stage and the loudspeaker. Refer to
f igure 17.

There is absolutely no perfor­mance limitation with an Autoform­er. Its frequency response exceeds
that of the output circuit itself, and
extends well beyond the audible
range. Its distortion level is so low it
is virtually impossible to measure.

In the rare event of a power

Figur e 14

amplifier output circuit failure, the

15

Technical Description, con’t

McIntosh Autoformer provides absolute protection
from possible damage to your valuable loudspeakers.
The unequaled expertise of McIntosh in the design
and manufacturing of Autoformers is legendary in the
high fidelity industry. McIntosh engineers know how
to do it right.

Power Output Meter

The McIntosh MC462 has large Output Watt Me­ters that respond
95% full scale to
a single cycle tone
burst at 2kHz.
Refer to figure

18. Voltage and
current outputs
are electronically
measured, multi­plied and fed to a
special circuit that
accelerates the
pointer movement

Figur e 18

in the upward direction. Refer to figure 25 on the next
page. When the pointer reaches its peak it pauses only
long enough for the human eye to perceive its position,
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.

Protection Circuits

The MC462 incorporates the McIntosh Sentry Moni­tor Output Tran­sistor Protection
Circuit. Refer to
Figure 19. There is
absolutely no com­promise in sonic

Normal Operating Area

performance with
this circuit, and it
ensures safe opera­tion of the ampli­fier under even

Sentry Monitor
Safety Area

Fig ure 19

Output
Transistor
Failure

the most extreme
operating conditions. The different types of protection
circuits incorporated in the MC462 insure a long and
safe operating life. This is just one of the many char­acteristics of McIntosh Power Amplifiers that make
them world famous.

The MC462 also includes the unique patented
McIntosh Power Guard circuit. Power Guard elimi­nates the possibility of ever overdriving the amplifier
into clipping. Refer to
figures 20, 21 and 22.

Input Test Signal

(14kHz & 15kHz)

An overdriven amplifier
can produce both audible
and inaudible distortion
levels exceeding 40%.
The audible distortion is
unpleasant to hear, but
the inaudible ultrasonic
distortion is also undesir­able, since it can damage
valuable loudspeaker
system tweeters. You

Figure 20

will never experience

the harsh and damaging

Without Power Guard

distortion due to clipping.

The Power Guard
circuit is a waveform
comparator, monitoring
both the input and output
waveforms. Under normal
operating conditions,
there are no differences
between the shape of
these waveforms. If the
amplifier is overdriven,
there will be a difference
between the two signal
waveforms. When the

Figu re 21

With Power Guard

difference exceeds 0.3%,
the Power Guard acti­vates the PG light and
a dynamic electronic
attenuator at the ampli­fier input reduces the
input volume just enough
to prevent any further in­crease in distortion. The
Power Guard circuit acts
so fast that there are ab-

Figure 22

solutely no audible side
effects and the sonic purity of the music reproduction
is perfectly preserved. The MC462 Power Ampli­fier with Power Guard is not limited to just the rated
power output, but will actually produce distortion free
output well above its rated power due to the McIntosh
philosophy of conservative design.

16

Technical Description, con’t

Block Diagram

of the

POWER

CONTROL

Power Supply

AC Power

BACKUP

POWER SUPPLY

LIGHTING

CONTROL

INRUSH

CURRENT

LIMITER

CONTROL

LOGIC

Figure 23

Power Supply Circuits

To compliment the design of the MC462 Power Am­plifier Circuitry, there is a high current high voltage
power supply. Refer to figures 23 and 26.
The very large Power Transfomer can supply over 13
amps of current. Refer to figure 24 (golf ball is for
size comparsion).

MAIN RELAYS

The power amplifier draws high current from the AC
power line. Therefore, it is important that they plug
directly into the wall outlet.
Also, most owners desire one power switch for the
whole audio system. The MC462 is equipped with a
circuit that provides remote Power Control from a Mc­Intosh A/V Control Center. Refer to figure 26. When
the A/V Control Center is switched On, a (+5V) signal
operates the power relay in the MC462. The MC462
also has two remote Power Control Out Jacks. The
Power Control signal from these jacks is delayed by a
fraction of a second so that the turn on power surge of
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 high power Home Systems employing multiple
MC462 Power Amplifiers.

Figure 24

It is enclosed in the legendary McIntosh Potted Enclo­sures and weighs 30 lbs. The six super size main filter
capacitors can store over 350 Joules of energy which
is necessary for the wide dynamic range that “Digital
Audio” demands. Refer to figure 25.

Figure 25

Figure 26

17

Specications

Specications

Power Output

Minimum sine wave continuous average power output
per channel, with both channels operating is:
450 watts into 2 ohm load
450 watts into 4 ohm load
450 watts into 8 ohm load

Output Load Impedance

2, 4 or 8 ohms

Rated Power Band

20Hz to 20,000Hz

Total Harmonic Distortion

0.005% maximum harmonic distortion at any power
level from 250 milliwatts to rated power, 20Hz to
20,000Hz

Dynamic Headroom

3.0d B

Frequency Response

+0, -0.25dB from 20Hz to 20,000Hz
+0, -3.0dB from 10Hz to 100,000Hz

Intermodulation Distortion

0.005% 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 40

Input Impedance

22,000 ohms Balanced
22,000 ohms Unbalanced

Voltage G a i n

29dB, 8 Ohms
26dB, 4 Ohms
23dB, 2 Ohms

Power Guard

Less than 2% Total Harmonic Distortion with up to a

14dB overdrive signal

Power Control Input

5-15VDC, less than 1mA

Power Requirements

Field AC Voltage conversion of the MC462 is not
possible. The MC462 is factory configured for one of
the following AC Voltages:

100V ~ 50/60Hz at 12 Amps
110V ~ 50/60Hz at 11 Amps
120V ~ 50/60Hz at 10 Amps
127V ~ 50/60Hz at 10 Amps
220V ~ 50/60Hz at 6 Amps
230V ~ 50/60Hz at 6 Amps
240V ~ 50/60Hz at 6 Amps
Standby: less than 0.5 watt

Note: Refer to the rear panel of the MC462 for the cor-

rect voltage.

Overall Dimensions

Width is 17-1/2 inches (44.5cm)
Height is 9-7/16 inches (24cm) including feet
Depth is 22-1/2 inches (57.2cm) including the Front
Panel, Handles and Cables

Weight

115 pounds (52.3 kg) net, 148 pounds (67.3 kg) in ship­ping carton

Input Sensitivity (for rated output)

4.2 Volts Balanced

2.1 Volts Unbalanced

Signal To Noise Ratio (A-Weighted)

95dB Balanced (122dB below rated output)
93dB Unbalanced (120dB below rated output)

18

Power Control Output 1 and 2

12VDC, 50mA maximum total
Output is delayed 0.2 seconds from turn On

Shipping Carton Dimensions

Width is 29-1/2 inches (74.93cm)
Depth is 29 inches (73.66cm)
Height is 17 inches (43.18cm)

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 plastic
feet are attached to the bottom of the equipment. Four
1/4 - 20x2-1/4 inch screws and washers must be used
to fasten the unit securely to the bottom pad and wood
skid. This will ensure the proper equipment location
on the bottom pad. Failure to do this will result in
shipping damage.
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 2. Please
see the Part List for the correct part numbers.

Quantity Part Number Description
1 034052 Shipping carton top
1 034051 Shipping carton bottom
2 034054 Foam Pad (top and
bottom)
2 034186 Foam Pad (front and rear)
2 034187 Foam Pad (sides)

Packing Instructions

1 034136 Inner carton top
1 034137 Inner carton bottom
1 034188 Foam Pad (inner carton)
1 034479 Shipping skid
4 401212 1/4 - 20x2-1/4 cap screw
4 104058 Flat washer

19

McIntosh Laboratory, Inc.

2 Chambers Street
Binghamton, NY 13903
www.mcintoshlabs.com

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. 04187400