McIntosh MI254 Owner's Manual

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

MI254

Four Channel

Power Amplifier

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 MI254 Four Channel 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: 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..................................................................		4
Installation...................................................................		5
Rear Panel Connections, Switches and Selection.....		6-7
Output Terminals and How to Connect..................		8-13
Front Panel Displays and Push-button.......................		14
How to Operate..........................................................		15
Photos...................................................................		16-17
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 MI254.

2.The MI254 mutes the speaker output for approximately two seconds when first turned on.

3.Included with the MI254 and located in the Owner’s Manual Packet are two Side Rack Mounted Brackets and screw fasteners. Below are graphic images of the MI254 with and without the Side Rack Mounted Brackets attached. Refer to page 5 for installing the Side Rack Mount Brackets.

MI254 4 Channel Power Amplifier

MI254 4 Channel Power Amplifier with

Side Rack Mount Brackets installed

4.For the best performance and safety it is important to always attach a single Loudspeaker with an 8 Ohm or 4 Ohm impedance to the Channel 1 - Channel 4 output terminals. Refer to “How to Connect” pages 8 thru 13.

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

it to the McIntosh MI254.

Copyright 2018 © by McIntosh Laboratory, Inc.

2

3/10 of an inch (7.6millimeters)

PIN 2 PIN 1

PIN 3

General Information, con,t and Cable Information, Introduction and Performance Features

5. In the event the MI254 Channel(s) over heat, due to improper ventilation or Loudspeaker Impedance, the protection circuits will activate. The Front Panel Channel LED will change color and the audio will be muted. Refer to page 15. When the MI254 has returned to a safe operating temperature, Channel(s) normal operation will resume.

6.For additional information on the MI254 and other McIntosh Products please visit the McIntosh Website at www.mcintoshlabs.com.

Connector and Cable Information

XLR Connectors

Below is the Pin configuration for the XLR Balanced Input, Input/Output Connectors on the MI254. Refer to the diagram for connection:

PIN 1: Shield/Ground

PIN 2: + Input/Output

PIN 3: - Input/Output

Power Control Connector

The MI254 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	Power
	of the MI254 Meter Power Output
		Control
	Indicators. The 3.5mm stereo mini
		Meter
	phone plug connects to a McIntosh	Illumination
		Control Ground
	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 (7.6mm)

Introduction

Now you can take advantage of traditional McIntosh standards of excellence in the MI254 Power Amplifier. The Four Channel Power Amplifier produces high power output per channel and will drive quality Loudspeakers to a high level of performance. The MI254 reproduction is sonically transparent and absolutely accurate. The McIntosh Sound is “The Sound of the Music Itself.”

Performance Features

• Power Output

The MI254 consists of Four Power Amplifier Channels, each capable of 250 watts into 8 ohms 300 watts into 4 ohms Loudspeakers with distortion less than 0.025%.

• Loudspeaker Guard

The McIntosh Loudspeaker Guard Circuit prevents the amplifier from being over driven into clipping, with its harsh distorted sound that can damage your valuable Loudspeakers.

• Versatile Operation

The MI254 can provide power amplification for four channels in a single Zone A/V System or two channels for each of a Dual Zone A/V System.

• Balanced, Unbalanced and Bus Inputs

There are Balanced, Unbalanced and Bus Connections for all four Power Amplifier Input Channels.

• Sentry Monitor and Thermal Protection

McIntosh Sentry Monitor power output stage protection circuits ensure the MI254 will have a long and trouble free operating life. Built-in Thermal Protection circuits guard against overheating.

• Illuminated Power Meters

The Illuminated Power Output Watt Meters on the MI254 are peak responding, and indicates the Power Output of the amplifiers.

• Power Control

The McIntosh Power Control Circuit allows for remote turn-on of the MI254 Power Amplifier from a McIntosh A/V Control Center or Preamplifier for a single or dual Zone System.

• Special Power Supply

A regulated Power Supply ensures stable noise free operation even though the power line varies.

• LED Solid State Front Panel Illumination

The even Illumination of the Front Panel is accomplished by extra long life Light Emitting Diodes (LEDs). The Metal and Glass Front Panel ensures the pristine beauty of the MI254 will be retained for many years.

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Dimensions

Dimensions

The following dimensions can assist in determining the best location for your MI254.

Front View of the MI254

17-1/2"

44.5cm

3-15/32" 4-5/16" 8.8cm 11.0cm

	Front View of the MI254 with Side Mount Brackets	Side View of the MI254
	19"
	48.3cm	18-1/2"
		47.0cm
		17-1/16"
		43.3cm

3/16" 3-1/4"

.5cm 8.2cm

	Rear View of the MI254	.25"
	16-1/2"	.64cm
		2.0"	13-19/32"	1-5/16"
	41.9cm
		5.0cm	34.7cm	3.4cm

13-1/4"

33.7cm

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Installation

Installation

The MI254 needs to be placed upright on its four feet. It also can be custom installed. Remove the four feet when it is custom installed and retain them with the fastening screws for possible future use. The required panel cutout, ventilation cutout and unit dimensions are shown in the drawing on the right side of this page.

It is necessary to provide adequate ventilation for cool operation, ensuring long life for the MI254. Do not install the MI254 above heat generating components. When the MI254 is installed in a cabinet with other components, use a ventilation fan to provide cool operating temperature.

A custom cabinet installation needs to provide the following minimum spacing for cool operation:

Allow at least 3 inches (7.6cm) 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 MI254, providing

airflow. Allow 2-1/2 inches (6.35 cm) in front of the mounting1 panel for clearance. Be sure to cut out a ventilation hole in the mounting shelf according to the dimensions in the drawing.

1When the MI254 is installed together with other McIntosh Components, check clearances on all components before proceeding.

Installation of Side Rack Mount Brackets

When desired, to install MI254 Side Rack Mounting Brackets, follow the steps below for one side at a time:

1.Refer to figure A to remove the two side screws and save them for possible future use.

2.Position the Side Rack Mounting Bracket as illustrated in figure B. Then attach the Bracket to the Front and Side Panel of the MI254, using the screws supplied with the Bracket.

3.Perform steps 1 and 2 to mount the second Bracket to the other side of the MI254.

		16-7/8"
		42.8cm
MI254 Front Panel		3-1/4"
		8.2cm
Custom Cabinet Cutout
	3"	Cutout Opening for Custom Mounting

7.6cm

Cabinet Front Panel

Opening for Ventilation

MI254 Side View

in Custom Cabinet

MI254 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.

	Cutout Opening for Ventilation
Support			Chassis
Shelf	25/32"		Spacers
	2.0cm
29/32"	10-9/16"
	26.9cm
2.4cm		14-7/16"	15"
	Cutout Opening
			38.1cm
		36.2cm
	for Ventilation
3"	11-19/32"
7.6cm	29.7cm

	Front Panel	Front Panel
			Side Panel
		Side Panel
		Side Rack
		Mounting
		Bracket
	Remove two	Supplied	Supplied
			Screws
		Screws
	Screws from
	the Chassis
	Sidewall
	and save
	them
	Figure A	Figure B

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				Rear Panel Connections and Switches
BALanced Input	BALanced Input	BALanced Input	BALanced Input CHAN-	Main Fuse, refer to the
CHANNEL 4/Left	CHANNEL 3/Right	CHANNEL 2/Left	NEL 1/Right	Rear Panel for the correct
				fuse size and rating

UNBALanced Input	UNBALanced Input	UNBALanced Input	UNBALanced Input
CHANNEL 4/Left	CHANNEL 3/Right	CHANNEL 2/Left	CHANNEL 1/Right

Connect the MI254 Power Cord to a live

AC Outlet

BUS 1 Left and Right INput and OUTput Connections1 Jacks

BUS 2 Left and Right INput and

OUTput Connections1 Jacks

	PWR CNTRL (Power Control)
	IN receives turn On/Off signal
	from a McIntosh component.
	PWR CNTRL (Power Control)		CHANNEL 4/Left	CHANNEL 3/Right		CHANNEL 2/Left	CHANNEL 1/Right
	OUT sends a turn On/Off signal
			Input Selector Switch1	Input Selector Switch1		Input Selector Switch1	Input Selector Switch1
	to another McIntosh Component
	CHANNEL 4/Left Output		CHANNEL 3/Right Output		CHANNEL 2/Left Output		CHANNEL 1/Right Output
	Connections for a 4 ohm		Connections for a 4 ohm or		Connections for a 4 ohm or		Connections for a 4 ohm or
	or 8 ohm Loudspeaker		8 ohm Loudspeaker		8 ohm Loudspeaker		8 ohm Loudspeaker

1 Refer to page 7 for detailed information about utilization of the CHANNEL 1-4 Input Switches and the functioning of the BUS 1-2 INput and OUTput connection jacks

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