McIntosh MC252 User Manual

Power Amplifier

MC252

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.

2

Thank You

Your decision to own this McIntosh MC252 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
Thank You and Please Take a Moment.............................	3
Technical Assistance and Customer Service ....................	3
Table of Contents and Important Information ..................	3
Connector Information .....................................................	4
Introduction ......................................................................	4
Performance Features .......................................................	4
Dimensions .......................................................................	5
Installation ........................................................................	6
Top Panel Connections and Switch ..................................	7
How to Connect in Stereo.................................................	8
How to Connect in Mono Bridged Mode .......................	10
How to Connect in Mono Bi-Amp (Parallel) .................	12
Front Panel Displays and Controls .................................	14
How to Operate...............................................................	15
Technical Description .....................................................	16
Notes ...............................................................................	20
Specifications .................................................................	22
Packing Instruction .........................................................	23

Important Information

Caution: The MC252 Amplifier weight is 94.5 pounds (42.87 kilograms). It requires two or more persons to safely handle when moving the amplifier.

1.The following Connecting Cable is available from the McIntosh Parts Department:

Power Control Cable Part No. 170-202

Six foot, 2 conductor shielded, with two 1/8 inch stereo mini phone plugs.

2.For additional connection information, refer to the owner’s manual(s) for any component(s) connected to the MC252.

3.The MC252 mutes the speaker outputs for approximately two seconds when first turned on.

4.It is very important that loudspeaker cables of adequate size be used, so that there will be no power loss. The size is specified in Gauge Numbers or AWG, (American Wire Gauge). The smaller the Gauge number, the larger the wire size:

If your loudspeaker cables are 50 feet (38.1m) or less, use at least 14 Gauge.

If your loudspeaker cables are 100 feet (76.2m) or less, use at least 12 Gauge.

5.In the event the MC252 over heats, due to improper ventilation and/or high ambient temperature, the protection circuits will activate. The Power Guard LED will stay ON and the audio will be muted. When the MC252 has returned to a safe operating temperature, normal operation will resume.

Copyright 2003 by McIntosh Laboratory, Inc.

3

Connector Information

XLR Connectors

Below is the Pin configuration for the XLR Balanced Input Connectors on the MC252. Refer to the diagram for connection:

PIN 1: Shield/Ground	Pin 2				Pin 1
PIN 2: + Input
PIN 3: - Input					Pin 3

Power Control and Trigger Connectors

The MC252’s Power Control Outputs provide a 5 volt signal. Use a 1/8 inch stereo mini

phone plug to connect to the Positive Power Control Input on other

N/C

McIntosh Components.

Ground

Introduction

Now you can take advantage of traditional McIntosh standards of excellence in the MC252 Power Amplifier. The 250 watt high current outputs will drive any high quality Loudspeaker System to its ultimate performance. The MC252 reproduction is sonically transparent and absolutely accurate. The McIntosh Sound is “The Sound of the Music Itself.”

Performance Features

• Power Output

The MC252 consists of two separate power amplifier channels, each capable of 250 watts into 2, 4 or 8 ohm speakers with less than 0.005% distortion. The two channels can be combined into a single channel with 500 watts into 1, 2, 4, 8 or 16 ohm speakers with less than 0.005% distortion.

• Patented Autoformers

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

• Patented 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 Loudspeakers.

• Balanced and Unbalanced Inputs

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

•Patented Sentry Monitor with Thermal Protection

McIntosh Sentry Monitor power output stage protection circuits ensure the MC252 will have a long and trouble free operating life. Built-in Thermal Protection Circuits guard against overheating.

•Power Control

The McIntosh Power Control Circuit allows for remote turn-on of the MC252 Power Amplifier from a McIntosh Audio/Video Control Center or Preamplifier. If any additional McIntosh Power Amplifiers are part of the system, a delayed Power Control Output Trigger is available. This delayed Trigger reduces the strain on the house’s electrical wiring and protection devices.

• Illuminated Power Meters

The Illuminated Power Output Watt Meters on the MC252 are peak responding, and indicate the 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.

•Fiber Optic Solid State Front Panel Illumination

The Illumination of the Front Panel is accomplished by the combination of custom designed Fiber Optic Light Diffusers and Light Emitting Diodes (LEDs). This provides even Front Panel Illumination, together with the extra long life LEDs.

•Glass Front Panel and Super Mirror Chassis Finish

The famous McIntosh Illuminated Glass Front Panel with a three dimensional look and the Stainless Steel Chassis with Super Mirror Finish ensures the pristine beauty of the MC252 will be retained for many years.

4

Connector Information, Introduction, Performance Features and Dimensions

The following dimensions can assist in determining the best location for your MC252. There is additional information on the next page pertaining to installing the MC252 into cabinets.

17-1/2"

44.45cm

8-13/16" 9-7/16" 22.38cm 23.97cm

Front View of the MC252

16-13/16" 42.70cm

Rear View of the MC252

13-1/4"

33.66cm

14-1/2"

36.83cm

13-5/8"

34.61cm

Side View of the MC252
	8-1/8"
	20.64cm
			8-3/16"
			21.11cm

7/8"

9-1/2"

1-1/16"

2.22cm

24.13cm

2.70cm

5

					Installation
	Installation
	Caution: The MC252 Amplifier weight is 94.5 pounds		(40.64 cm) depth behind the front panel. Allow 1-3/16
	(42.87 kilograms). It requires two or more persons		inches (3.02 cm) in front of the mounting panel for knob
	to safely handle when moving the amplifier.		clearance. Be sure to cut out a ventilation hole in the
	The MC252 can be placed upright on a table or shelf,
			mounting shelf according to the dimensions in the drawing.
	standing on its four feet. The
	four feet may be removed			17-1/16"
	from the bottom of the
				43.34cm
	MC252 when it is custom
	installed as outlined below.
	The four feet together with
	the mounting screws should
	be retained for possible fu-				8-5/16"
	ture use if the MC252 is re-	MC252 Front Panel			21.11cm
	moved from the custom in-
		Custom Cabinet Cutout
	stallation and used free
	standing. It also can be cus-
	tom installed in a piece of
	furniture or cabinet of your
	choice. The required panel			Cutout Opening	Alternate Rear Foot Location
	cutout, ventilation cutout			for Custom Mounting
	and unit dimensions are
	shown.	Cabinet		6"
	Always provide adequate			15.24cm
		Front
	ventilation for your MC252.	Panel
	Cool operation ensures the
	longest possible operating	Opening
	life for any electronic instru-
		for Ventilation
	ment. Do not install the
	MC252 directly above a heat
	generating component such
	as a high powered amplifier.
	If all the components are in-	MC252 Side View
	stalled in a single cabinet, a	in Custom Cabinet
	quiet running ventilation fan
	can be a definite asset in
	maintaining all the system
	components at the coolest			Cutout Opening for Ventilation
	possible operating tempera-	Support
	ture.			1-1/4"
		Shelf
	A custom cabinet instal-			3.18cm
	lation should provide the fol-
	lowing minimum spacing
	dimensions for cool opera-			11-1/2"
	tion. Allow at least 6 inches
				29.21cm
	(15.24 cm) above the top, 2	MC252 Bottom View
					14-3/8"
	inches (3.81cm) below the	in Custom Cabinet
				Cutout Opening	36.51cm
	bottom and 1 inch (2.54 cm)
				for Ventilation
	on each side of the amplifier,
	so that airflow is not ob-
	structed. Allow 16 inches
	6

Top Panel Connections and Switch

Main Fuse holder, refer to information on the top back panel of the MC252 to determine the correct fuse size and rating

POWER CONTROL IN receives a turn On/Off Trigger from a McIntosh component. POWER CONTROL OUT sends a turn On/ Off Trigger to the next McIntosh component

UNBALANCED INPUTS for an audio cable from a preamplifier or control center audio outputs

RIGHT Channel OUTPUTs connections for 2 ohm, 4 ohm and 8 ohm Loudspeakers

Connect the MC252 power cord to a live AC outlet. Refer to information on the back panel to determine the correct voltage

MODE switch selects	LEFT Channel OUTPUTs
between three modes of	connections for 2 ohm, 4 ohm
operation; STEREO,	and 8 ohm Loudspeakers
MONO (BRIDGED) or
MONO (BI-AMP)
Parallel

BALANCED INPUTS for an audio cable from a preamplifier or control center audio outputs

7

How to Connect in Stereo

Caution: The supplied AC Power Cord should not be connected to the Rear Panel of the MC252 Amplifier until after the Loudspeaker Connections have been made and the supplied protective Terminal Connection Covers have been installed. Failure to observe this could result in Electric Shock.

1.For Remote Power Control, connect a power control cable from the Control Center or Preamplifier Power Control Out to the MC252 Power Control In.

2.Connect cables from the Unbalanced Output of a McIntosh Preamplifier or Control Center to the MC252 Unbalanced Inputs.

Note: An optional hookup is to use balanced cables.

3.Prepare the Loudspeaker Hookup Cables that attach to the MC252 Power 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. Tighten the top portion of the terminal post and the set screw to secure the banana plug in place.

Note: The use of Banana

Plugs is for use in the

United States

and Canada only.

4.Connect the Loudspeaker hookup cables to the output terminals that match the impedance of the Loudspeaker, being careful to observe the correct polarities. Output impedance connections of 2S (ohm), 4S (ohm) and 8S (ohm) 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. For additional instruction on making Loudspeaker Connections contact your McIntosh Dealer or McIntosh Technical Support.

5.Attach the supplied Terminal Connection Covers with the four Mounting Screws (6-32 x 1/4 inch Phillips Head) to the Rear Panel of the MC252 Amplifier. Refer to figure 9.

Note: The illustration in figure 9 is for the purpose of installing the Terminal Connection Covers, showing the opening on the covers for the Loudspeaker Cables to exit the MC252. It is not intended to show which terminal connections to use.

6.Connect the MC252 power cord to an active AC outlet.

Terminal Connection Covers

Cable Openings

Cover Mounting	Cover Mounting
Screw Locations	Screw Location
	Figure 9

8