McIntosh MA252 User manual

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

MA252

Integrated 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 MA252 Integrated
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

Important Information ......................................................... 3

Unpacking the MA252 .....................................................4-5

General Information ............................................................ 6

Connector and Cable Information ....................................... 6

Introduction ......................................................................... 7

Performance Features .......................................................... 7

Dimensions .......................................................................... 8

Installation ........................................................................... 9

Connections:

Rear Panel Connections ..................................................... 10

Connecting Components .............................................. 11-12

Connecting Loudspeakers ............................................ 13 -14

Remote Control and Front Panel:

Remote Control Push-buttons ........................................... 16

How to use the Remote Control ......................................... 17

Front Panel Displays, Controls and Jack ........................... 18

Setup Mode:

How to Operate the Setup Mode ....................................... 19

Setup Functions:

Default Settings ......................................................... 19

Fi r mware Versi o n ......................................................19

Source Input On/Off and Renaming ....................19-21

Data Por t .................................................................... 21

Remote Control Codes ............................................... 21

IR Sensor ....................................................................22

Power Mode ...............................................................22

Factory Reset .............................................................22

Operation:

How to Operate the MA252 .........................................24-27

Trim Functions:

Balance .......................................................................24

Tri m Level ..................................................................25

Tone Control...............................................................25

Bass Control ............................................................... 25

Treble Contr ol ............................................................26

Information Display ...................................................26

Trim, Mute, Headphone Jack and Power Guard ........ 26

Protection Circuitry and Microprocessor Reset ......... 27

Photos ............................................................................28 -29

Specifications.....................................................................30

Packing Instructions .......................................................... 31

Copyright 2017 © by McIntosh Laboratory, Inc.

2

IMPORTANT!

INSTRUCTIONS FOR REMOVAL

OF FOAM INSERT OVER THE

VACUUM TUBES PRIOR TO

CONNECTING THE A.C. POWER

SUPPLY CORD, START ON THE

NEXT PAGE.

3

Caution: To prevent damage to the MA252

Tubes during shipping, there is a
special foam insert surrounding the
Tubes of the Integrated Amplifier.

The Foam Insert must be

removed from the MA252
before connecting the AC
Power Supply Cord to the
integrated amplifier.

2. Remove the Warning Sheet and save it with the
Shipping Carton for possible future use. Refer to
figures A and B.

3. Carefully lift upright the Foam Insert Vacuum
Tube Cover and place it near to the MA252 Inte­grated Amplifier. Refer to figure C.

Remove the
Foam Insert
Vacuum
Tube Cover

Failure to do so has the po-

tential of a Fire Hazard,
resulting in damage to the
MA252 and the surrounding
environment.

Follow these instructions for

removal of the packing foam
before connecting the AC
Power Supply Cord to the
MA252.

The MA252 has no user serviceable parts,
including the tubes. If repairs are needed they
must be performed by an authorized McIntosh
Service Agency. Follow the steps below to pre­pare the MA252 for operation:

1. Orient the MA252 so the Front and Top of the
Integrated Amplifier is facing you. Refer to
figure A.

WARNING

TO AVOID A FIRE HAZARD, THE FOAM INSERT
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 MA252 OWNER’S

MANUAL FOR INSTRUCTIONS.

Figure A

Remove the Warning Sheet

Figure B

Vacuum Tube Shield Covers

Figure C

4. Remove from the Foam, the four Vacuum Tube
Shield Covers and place them along the side of the
MA252 Integrated Amplifier. Save the Foam In­sert Vacuum Tube Cover with the Shipping Carton
for possible future use. Refer to figure D.

Remove the four Vacuum Tube Shield Covers

Figure D

4

WA R NI NG:

The supplied Vacuum Tube Shield
Covers must be installed over each
of the four Small Vacuum Tubes
before the MA252 Integrated Am­plifier is connected to AC Power
and activated for use!!

Failure to do so has the potential to
cause physical harm to human be­ings and animals.

Unpacking the MA252

5. The MA252 Integrated Amplifier has four Small
Vacuum Tubes that are inserted into special
Vacuum Tube Sockets on the Stainless Steel Chas­sis. Refer to figure E.
Each of the Tube Sockets have four pin openings
to accept the Vacuum Tube Shield Covers. Refer
to figure F.
Carefully install the Vacuum Tube Shield Covers
into each of the Vacuum Tube Sockets orienting
the Shield so the “Mc” on top of the Shield is fac­ing forward. Refer to figures G and H.

This could also result in damage to
the Vacuum Tubes and the MA252
Internal Circuitry.

It also prevents the potential of a
Fire Hazard, resulting in damage
to the MA252 and the surrounding
environment.

Figure E

Pin Openings

Figure G

Special Vacuum Tube Sockets

Vacuum Tube
Shield Covers

BAL 15%

Figure F

Figure H

5

General Information

1. For additional connection information, refer to the
owner’s manual(s) for any component(s) connected
to the MA252.

2. Apply AC Power to the MA252 and other McIntosh
Component(s) only after all the system components
are connected together. Failure to do so may cause
a malfunction of system operations as the Micro­processor’s Circuitry inside the components is
active when AC Power is applied.

3. The MA252 includes an Auto Off Power Save
Feature and the default setting is enabled. For
additional information including how to disable it,
refer to page 22.

4. When Power Amplifier Protection Circuitry of the
MA252 has activated, the Vacuum Tubes LEDs are
illuminated continuously with the color orange and
the sound will be muted.

5. When the Power Transformer has overheated due
to improper ventilation and/or high ambient operat­ing temperature, AC Power is removed from the
MA252. Normal operation will resume when the
operating temperature is in a safe range again.

6. For the best performance and safety, it is important
to always match the impedance of the Loudspeaker
to the Power Amplifier connections. Refer to pages
10 and 11.

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 MA252.

General Information, Connector and Cable Information

7. The MA252 Remote Control is capable of operat­ing other components. For additional information
go to www.mcintoshlabs.com.

8. 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.

9. For additional information on the MA252 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 Connectors on the MA252. Refer to the diagram
for connection:
PIN 1: Shield/Ground
PIN 2: + Output

PIN 1

PIN 3: - Output

Power Control Connector

The Power Control Output Jack sends Power On/
Off Signals (+12 volt/0 volt) when
another McIntosh Component is
connected. A 3.5mm stereo mini
phone plug is used for connection to
the Power Control Output.

Data Port Connector

The Data Out Ports send Remote Control Signals to
Source Components. A 3.5mm stereo
mini phone plug is used for connec­tion.

PIN 3

Power
Control

Data
Signal

PIN 2

N/C

Ground

N/C

Data
Ground

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. 6 mm)

3/10 of an inch
(7.6millimeters)

6

Introduction

Now you can take advantage of traditional McIntosh
standards of excellence in the MA252 Integrated Am­plifier. The Power Amplifier Solid State section of the
MA252, with a power output of 100 watts per channel,
will drive a pair of quality Loudspeakers to a high
level of performance.

The flexible Tube Preamplifier section provides

connections for various analog input sources.

The MA252 reproduction is sonically transparent
and absolutely accurate. The McIntosh Sound is “The
Sound of the Music Itself.”

Performance Features

• Power Output

The MA252 consists of 100 watts (8 ohm) or 160 watts
(4 ohm) per channel Stereo Power Amplifier with
less than 0.03% distortion. The McIntosh MA252 is
designed for connection of a single 8 ohm or 4 ohm
Loudspeaker per channel. The Power Amplifier uses
Ther malTrak1 Output Transistors for lower distortion
and cool operation.

• Power Guard

The patented McIntosh Power Guard circuit prevents
amplifier clipping and protects your valuable Loud­speakers.

• Sentry Monitor and Thermal Protection

McIntosh Sentry Monitor power output stage protec­tion circuits ensure the MA252 will have a long and
trouble free operating life. Built-in Thermal Protection
Circuits guard against overheating.

• Electronic Output Switching

The Preamplifier uses Logic Controlled Electromag­netic Switches on all low level outputs and operating
functions for reliable, noiseless, distortion free switch­ing.

• Moving Magnet Phono Inputs

The MA252 Moving Magnet Input Circuitry uses
the latest design to provide the lowest possible noise,
distortion and flat frequency response.

• Tone Controls

The Bass and Treble Trim Controls provide up to
10dB of boost or cut. The MA252 remembers the Bass
and Treble Setting for each input.

• Multifunction Display

The Front Panel Display indicates source selection,
volume levels and setup functions.

• Power Control Output

A Power Control connection for convenient Turn-On
of a McIntosh Component.

• Remote Control

The Data Port together with the supplied Remote Con­trol provide control of McIntosh Source Components
connected to the MA252.

• Special Power Supply

The large Power Transformer, multiple filter capaci­tors with 60 Joules of Energy Storage and regulated
Power Supply ensure stable noise free operation even
though the power line varies.

Introduction and Performance Features

• McIntosh Custom Binding Posts

McIntosh Patented 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.

• Super Mirror Finish Chassis with Glass Panel

The famous McIntosh Stainless Steel Chassis with
Super Mirror Finish ensures the pristine beauty of the
MA252 will be retained for many years. The famous
McIntosh Illuminated Glass Panel uses long life Light
Emitting Diodes (LEDs).

1

ThermalTrak™ and ON Semiconductor are trademarks of Semi-

conductor Components Industries, LLC

7

Dimensions

The following dimensions can assist in determining
the best location for your MA252. There is additional
information on the next page pertaining to installing
the MA252 into cabinets.

Front View of the MA252

16-1/2"

41.9cm

1-1/2"

3.8cm

Dimensions

Left Side View of the MA252

BAL 15%

1-1/2"

3.8cm

Top View of the MA252

14-3/4"

37.5cm

7-1/32"

17.9cm

7-5/8"

19.4cm

1-1/2"

3.8cm

Right Side View of the MA252

6-13/16"

17.3cm

4-1/16"

10.3cm

12"

30.5cm

3"

7.62cm

8

Installation

The MA252 Integrated Amplifier is designed to be
placed upright on a table or shelf, standing on its feet.
The required ventilation requirements are shown.
Always provide adequate ventilation for your MA252.
Cool operation ensures the longest possible operating
life for any electronic instrument. Do not install the
MA252 directly above a heat generating device, such
as a Power Amplifier. Allow at least 6 inches (15.3cm)
above the top, 5/8 inch (1.6cm) below the bottom and
2 inches (5.1cm) on each side of the Amplifier, so that
airf low is not obstructed. Allow 18 inches (45.7cm) of
depth for airf low and cable connections.

MA252 Front View

2"

5.1cm

6"

15.3cm

BAL 15%

Installation

2"

5.1cm

MA252 Side View

6"

15.3cm

18"

45.7cm

9

MA252 Rear Panel Connections

Main Fuse holder, refer to
information on the back
panel of your MA252 to
determine the correct fuse
size and rating

Right OUTPUT
connections for a 4 or
8 ohm Loudspeaker

POWER CONTROL OUTPUT sends turn
On/Off signals to a McIntosh Component
when the MA252 is switched On/Off

Left OUTPUT
connections for a 4 or
8 ohm Loudspeaker

PHONO accepts signals
from a Moving Magnet
Phono Cartridge or a
high output Moving Coil
Cartridge

Connect the MA252 power cord to a
live AC outlet. Refer to information
on the back panel of your MA252 to
determine the correct voltage for your
unit

10

DATA PORT sends signals
to a Source Component
to allow control with the
MA252 Remote Control

SUB (MONO) OUTPUT
full frequency range Audio
Output for connection to
an actively powered Sub­Woofer

BALANCED INPUTS
accept high level pro­gram source signals

GND terminal
accepts a ground
wire from a
turntable

UNBALanced INPUTS
1 and 2 accept high level
program source signals