2
Introduction (continued)
The MC451 has 150 watts of vacuum tube power
to drive your loudspeaker’s mid ranges and tweeters.
With the MC451, the tubes will not be challenged
or overloaded by low-end reproduction because the
solid state section has 300 watts dedicated to driving
the woofers.
Fine tuning your system is made simple with the
built-in crossover. This allows you to match the
crossover point to your loudspeakers and maximize
the power available to each section. Alternatively,
you can connect a direct feed to each amplifier
section and bypass the crossover. This is perfect if
you have crossovers external to the MC451.
The solid state amplifier features Power Guard
®
for clipping protection, Sentry Monitor™ for
over current protection, and ThermalTrak
1
output
transistors for stable bias and temperature control.
The output Autoformer™ provides the full 300W
of power regardless of loudspeaker impedance and
provides DC protection to the outputs.
The vacuum tube amplifier features Power
Guard SGS
®
for output tube protection and Sentry
Monitor™ for over current protection. The Unity
Coupled Output Transformer™ provides the full
150W of power regardless of loudspeaker imped-
ance and provides DC protection to the outputs.
Copyright 2022 © by McIntosh Laboratory, Inc.
Table of Contents
Safety First �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� 2
Introduction�� �� �� �� �� �� �� �� �� �� �� �� �� �� �� 2
Where to Put It� �� �� �� �� �� �� �� �� �� �� �� �� �� 3
Dimensions �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� 3
Removal of Foam Insert Over Vacuum Tubes �� 4
Connector Information �� �� �� �� �� �� �� �� �� �� 5
Connecting a Loudspeaker � �� �� �� �� �� �� �� �� 5
Front Panel Displays and Knobs �� �� �� �� �� 6-7
Rear Panel Connections and Switches �� �� �� 8-9
Connection Diagram �� �� �� �� �� �� �� �� �� 10-11
Setting Up the Crossover� �� �� �� �� �� �� �� 12-13
Solid State Specifications �� �� �� �� �� �� �� �� ��14
Vacuum Tube Specifications �� �� �� �� �� �� �� ��14
General Specifications� �� �� �� �� �� �� �� �� �� ��14
Packing Instructions �� �� �� �� �� �� �� �� �� �� ��15
Packaging Parts List �� �� �� �� �� �� �� �� �� �� ��15
Thank You from All of Us at McIntosh
You have invested in a precision instrument that
will provide you with many years of enjoyment.
Please take a few moments to familiarize yourself
with the features and instructions to get the maxi-
mum performance from your MC451.
If you need further technical assistance, please
contact your dealer who may be more familiar with
your particular setup including other brands. You
can also contact McIntosh with additional questions
or in the unlikely event of needing service.
McIntosh Laboratory, Inc�
2 Chambers Street
Binghamton, New York 13903
Technical Assistance
(607) 723-3512
Fax
(607) 724-0549
Customer Service
(607) 723-3515
Fax
(607) 723-1917
Website
www.mcintoshlabs.com
Please Take A Moment
For future reference, you can write down your
serial number and purchase information here. We
can identify your purchase from this information
if the occasion should arise:
Serial Number:
__________________________
Purchase Date:
___________________________
Dealer Name:
___________________________
Introduction
The MC451 Dual Mono Amplifier
is an all-in-one solution for bi-amping
loudspeakers. Utilizing our Hybrid
Drive™ technology, it captures
the harmonic beauty of vacuum tubes for a
loudspeaker’s mid and high ranges while still having
an abundance of power dedicated to the low end. The
MC451 does the work of two separate amplifiers with
its optimized combination of a vacuum tube and a
solid state amplifier in a single optimized instrument.
Safety First
Please read the safety instructions included in a
separate document called
Important Additional
Operation Information Guide
.
Actual size = .625” square
Hybrid Drive logo FINAL 2022.ai
1
ThermalTrak™ is a trademark of Semiconductor
Components Industries, LLC
