McIntosh C48 Owners Manual

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

C48

Audio Preamplifier

Owner’s Manual

The lightning ash 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 sufcient 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 appa-

ratus (including ampliers) 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

NO USER-SERVICEABLE PARTS

INSIDE. REFER SERVICING TO

QUALIFIED PERSONNEL.

third grounding prong. The wide blade or the
third prong are provided for your safety. If

the provided plug does not t 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.

11. Only use attachments/accessories specied by

the manufacturer.

12. Use only with the cart, stand, tripod, bracket,
or table specied 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 qualied service person­nel. Servicing is required when the apparatus
has been damaged in any way, such as power-

To prevent the risk of electric

shock, do not remove cover or

back. No user-serviceable parts

inside.

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 lled

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.

18. Do not expose batteries to excessive heat such

as sunshine, re or the like.

19. Connect mains power supply cord only to a
mains socket outlet with a protective earthing
connection.

2

Thank You

Your decision to own this McIntosh C48 Audio Pre­amplifier 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 ....................................................... 3

General Information .................................................. 4

Connector and Cable Information ............................. 4

Introduction ................................................................ 5

Performance Features ................................................ 5

Dimensions ................................................................ 6

Installation ................................................................. 7

Connections:

Rear Panel Connections .............................................. 8

(Separate Sheet) .................................................. Mc2B

Connecting Components ............................................. 9

Connection Diagrams

(Separate Sheets) .................. Mc1A, Mc1B and Mc2A

Remote Control:

Remote Control Push-buttons ................................... 10

How to use the Remote Control .................................11

Front Panel:

Front Panel Displays, Controls, Push-buttons

and Jack ..................................................................... 12

Setup:

How to Operate the Setup Mode .............................. 13

Default Settings......................................................... 13

Fi r mw a re Ver si o n ...................................................... 13

Source Inputs Reassignment ..................................... 13

Input Level Adjustment ............................................ 14

Power Mode .............................................................. 15

Display Brightness .................................................... 15

Passthru ..................................................................... 15

Power Control Triggers 1 and 2 ................................ 16

Comm Port Baud Rate .............................................. 16

Remote Control Codes .............................................. 17

Operation:

How to Operate the C48 ........................................... 18

Trim Functions ..................................................... 18 -20

Equalizer Bypass ...................................................... 21

Equalizer Controls .................................................... 22

Passthru ..................................................................... 22

Optical and Digital Inputs ......................................... 23

USB Input Operation with a Computer .................... 23

Reset of Microprocessors .......................................... 23

Resetting the C48 to default settings ........................ 23

Additional Information:

Photos ................................................................... 24 -25

Specifications ............................................................ 26

Packing Instruction ................................................... 27

Copyright 2010, 2012 © by McIntosh Laboratory, Inc.

3

General Information

1. For additional connection information, refer to the

owner’s manual(s) for any component(s) connected

to the C48 Audio Preamplifier.

2. The Main AC Power going to the C48 and any

other McIntosh Component(s) should not be applied

until all the system components are connected
together. Failure to do so could result in malfunc­tioning of some or all of the system’s normal opera­tions. When the C48 and other McIntosh Compo­nents are in their Standby Power Off Mode, the
Microprocessor’s Circuitry inside each component
is active and communication is occurring between
them.

3. Balanced and Unbalanced Inputs and Outputs can
be mixed. For example, you may connect signal
sources to Unbalanced Inputs and send signals
from the Balanced Outputs. You can also use Bal­anced and Unbalanced Outputs simultaneously,
connected to different Power Amplifiers.

4. The C48 internal Digital to Analog Converter

Circuitry is designed to decode 2-channel PCM

(Pulse Code Modulation) Digital Signal present at

the Coaxial and Optical Digital Audio Inputs. Other
Digital Audio Signal Format Types will cause the
Audio Outputs of the C48 to be muted and the Front
Panel Information Display will indicate an error
message.

5. The Remote Control Supplied with the C48 Pream-

plifier is capable of operating other components.
For additional information go to www.mcintosh­labs.com.

6. 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.

General Information and Connector Information

7. For additional information on the C48 and other
McIntosh Products please visit the McIntosh Web
Site at www.mcintoshlabs.com.

Connector and Cable Information

XLR Connectors

Below is the Pin configuration for the XLR Balanced
Input and Output Connectors on the C48. Refer to the
diagrams for connections:
PIN 1: Shield/Ground
PIN 2: + Output
PIN 3: - Output

PIN 2 PIN 1

PIN 3

PIN 1

Power Control and Trigger Connectors

The C48 Power Control Out, Trigger and Pass-Thru
Output Jacks send Power On/

Off Signals (+12 volt/0 volt)

when connected to other
McIntosh Components. An
additional connection is for
controlling the illumination of

Output 1&2, Trig 1&2

and Pass-Thru

Power
Control

Meter
Illumination
Control

the Power Output Meters on
McIntosh Power Amplifiers. A
1/8 inch stereo mini phone plug is used for connection
to the Power Control, Trigger and Pass-Thru Outputs
on the C48.

Note: The Power Control, Trigger, Pass-Thru and Data

Connecting Cable is available from the McIntosh
Parts Department:

Power Control, Trigger, Pass-Thru and Data
Cable Part No. 170-202

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

PIN 3

Ground

PIN 2

Data Port Connectors

The C48 Data Out Ports send Remote Control Signals
to Source Components. A 1/8
inch stereo mini phone plug is
used for connection.

Data
Signal

N/C

Data
Ground

4

Introduction

The McIntosh C48 Audio Preamplifier is one of the
finest Preamplifiers ever created. The versatile Pream­plifier provides connections for various input sources
both analog and digital. The C48 Outputs have the
ability to drive multiple Power Amplifiers. The C48
reproduction is sonically transparent and absolutely
accurate. The McIntosh Sound is “The Sound of the
Mu sic It self.”

Performance Features

• Electromagnetic Input Switching with Level Trim

Adjustment

Digital Logic integrated circuits drive Electromag­netic Switches on all Inputs and operating functions
for reliable, noiseless, distortion free switching. All
eight Inputs on the C48 can be matched in level, so
there are no abrupt changes in volume levels between
the different Inputs.

• Moving Coil and Moving Magnet Phono Inputs

The C48 contains two different precision Phono Pre­amplifier Circuits. One for low output Moving Coil
Phono Cartridges with selectable resistance loading,
the other is for Moving Magnet Cartridges with select­able capacitive loading. Both circuits use the latest
designs to provide the lowest possible noise and dis­tortion. The RIAA Correction Equalization Circuitry
utilizes close tolerance resistors and capacitors for an
extremely flat frequency response.

• Digital Audio Inputs

The C48 has Coaxial, Optical and USB Digital Inputs
to Decode PCM Signals from an external source. The
C48 Up Samples the Digital Signal to 192kHz with
32Bit resolution before the Digital to Analog process
begins. The USB Input sends basic commands (e.g.

Play/Pause, Next, Back, etc.) to the computer by using

the C48 Remote Control.

• Balanced Inputs

The Balanced Inputs allow the connection of a source
component using long cable lengths without a loss in
sound qual it y.

• Precision Tracking Volume Control

Volume levels are controlled by a new Multi-Stage
Precision Digitally Controlled Attenuator System with
a tracking accuracy of 0.1dB.

• Variable Rate Volume and Balance Controls

The C48 Preamplifier’s Volume and Balance Control
Circuitry provides an ideal rate of change with control
rotation.

• Equalizer Controls with Bypass

The Equalizer Circuitry provides 12dB of boost or cut
at five different center frequencies. When an Equal­izer Control is in the center position, all Circuit Com­ponents are removed from the Signal Path. The C48
remembers the Equalizer Circuitry Bypass Option for
each input.

• Pass-Thru Mode

The Automatic Pass-Thru Mode allows the C48 to be­come part of a Multichannel Sound System for DVD­Audio, SACD and Home Theater Movies.

• Alphanumeric Fluorescent Display

The Front Panel Information Display indicates the
Source Selection, Volume/Balance Levels and Setup
Mode Selections. The display intensity is adjustable.

Introduction and Performance Features

• Remote Control with External Sensor Input

The Remote Control provides control of the C48
operating functions and McIntosh Source Components
connected to it. Enjoy your McIntosh System from
another room in your home by connecting an external
sensor.

• Power Control Output and Trigger Assignment

A Power Control connection for convenient Turn-On
of McIntosh Power Amplifiers, Source Components
and Accessories is included. The Power Control Trig­ger Ouputs may be assigned to activate when a given
Input is selected.

• Special Power Supply

Fully regulated Power Supplies and a special R-Core
Power Transformer ensure stable noise free operation
even though the power line varies.

• Fiber Optic Solid State Front Panel Illumination

The even Illumination of the Front Panel is accom­plished by the combination of custom designed Fiber
Optic Light Diffusers and extra long life Light Emit-

ting Diodes (LEDs).

• Glass Front Panel and Super Mirror Chassis

Finish

The famous McIntosh Illuminated Glass Front Panel
and the Stainless Steel Chassis with Super Mirror
Finish ensures the pristine beauty of the C48 will be
retained for many years.

5

Dimensions

The following dimensions can assist in determining
the best location for your C48. There is additional
information on the next page pertaining to installing
the C48 into cabinets.

Front View of the C48

17-1/2"

44.45cm

Dimensions

Rear View of the C48

17-1/8"

43.50cm

13 -1/4"

33.66cm

5-3/8"

13.69cm

4-5/8"

11.75cm

6"

15.24cm

13/16"

2.06cm

1-15/16"

4.92cm

Side View of the C48

16-1/2"

41.91cm

14-1/2"

36.83cm

10-9/16"

26.83cm

3/16"

0.48cm

2"

5.08cm

4-13/16"

12.22cm

6

Installation

Installation

The C48 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 C48 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 C48
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 C48.
Cool operation ensures the longest possible operating
life for any electronic instrument. Do not install the
C48 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 2 inches (5.08cm) above the top, 2
inches (5.08cm) below the bottom and 1 inch (2.54cm)

on each side of the Preamplifier, so that airf low is not

obstructed. Allow 20 inches (50.8cm) depth behind the
front panel. Allow 1-7/16 inch (3.66cm) in front of the

mounting panel for knob clearance. Be sure to cut out
a ventilation hole in the mounting shelf according to
the dimensions in the drawing.

C48 Front Panel
Custom Cabinet Cutout

C48 Side View
in Custom Cabinet

C48 Bottom View
in Custom Cabinet

Cabinet Front Panel

Cabinet
Front
Panel

Support
Shelf

17-3/16"

43.66cm

Cutout Opening for Custom Mounting

Cutout Opening for Ventila ion

2-1/4"

5.72cm

9-1/8"

23.18cm

Cutout

Opening

Ventilation

15"

38.10cm

for

4-7/8"

12.38cm

Chassis
Spacers

15"

38.10cm

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

1-1/16"

2.70cm

12-5/16"

31.27cm

7

Rear Panel Connections

The identification of Rear Panel Connections for the
C48 Audio Preamplifier is located on a separate folded
sheet contained in the Owner’s Manual Packet.
Refer to separate sheet “Mc2B” for the Rear Panel
Connections.

Rear Panel Connections

C48 Audio Preamplifer Rear Panel

8

Connecting Components

The C48 has the ability to automatically switch power
On/Off to Source Components via the Power Control
connections. The Data Port Connections allow for
the remote operation of basic functions using the C48
Remote Control. With an external sensor connected
to the C48, remote control operation of the system is
possible from another room and/or when the C48 is
located in a cabinet with the doors closed.

The connection instructions below, together with
the C48 Input/Output/Control Connection Diagrams
located on the separate folded sheets “Mc1A/1B and
Mc2A”, are 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 4.

Note: Source components may be connected to the

C48 Balanced Inputs or Digital Inputs instead of
Unbalanced Inputs. Refer to Setup “Reassigning
Inputs” to activate them on page 13.

Power Control Connections:

1. Connect a Control Cable from the C48 POWER
CONTROL MAIN Jack to the Power Control In
on the Turntable.

2. Connect a Control Cable from the Turntable
Power Control Out Jack to the SACD/CD Player
Power Control In Jack.

3. Connect a Control Cable from the SACD/CD
Player Power Control Out Jack to the Tuner Power
Control In Jack.

4. Connect a Control Cable from the Tuner Power
Control Out Jack to the Music Server Power Con­trol In Jack.

5. Connect a Control Cable from the C48 POWER
CONTROL OUTPUT 1 Jack to the Power Ampli­fier Power Control In Jack.

Note: If two Power Amplifiers are used, connect the

Power Control Output of the first Amplifier to
the Power Control Input on the second Ampli­fier.

6. Optionally connect a Control Cable from the C48
POWER CONTROL OUTPUT 2 Jack to the

Power Amplifier (Secondary Room) Power Control

In Jack.

7. Connect any additional Components in a similar
manner, as outlined in steps 1 thru 4.

Data Control Connections:

8. Connect a Control Cable from the C48 TUNER

DATA PORTS Jack to the TUNER Data In Jack.

9. Connect a Control Cable from the C48 CD DATA

PORT Jack to the SACD/CD Player Data In Jack.

10. Connect a Control Cable from the C48 SRVR
DATA PORT Jack to the Music Server Data In
Jack.

11. Connect any additional McIntosh Components in a

similar manner, as outlined in steps 8 thru 10.

Sensor Connection:

12. Connect a Control Cable from the C48 IR Input

Connector to the external Sensor.

Audio Connections:

13. Connect an Audio Cable from the C48 TUNER

INPUT Jacks to the Tuner (Fixed) Output Jacks.

14. Connect an Audio Cable from the C48 CD IN-

PUT Jacks to the SACD/CD Player (Fixed) Output

Jacks.

15. Connect an Audio Cable from the C48 SRVR IN-

PUT Jacks to the Music Server Output Jacks.

16. Connect an Audio Cable from the C48 RECORD

OUTPUT Jacks to the Music Server Input 3 Jacks.

17. Connect the Audio Cables coming from the Turn-

table to the C48 MC PHONO INPUT Jacks.

Connecting Components

Note: If the Turntable has a Moving Magnet Car-

tridge connect the audio cables to the C48 MM
PHONO INPUT instead of the MC Input.

18. Connect Balanced Cables from the C48 BALanced
OUTPUT 1 connectors to the Power Amplifiers

Balanced (Left and Right) Inputs.

19. Optionally Connect an Audio Cable from the C48
BALanced OUTPUT 2 connectors to the Power

Amplifier (Secondary) Inputs.

20. Connect any additional McIntosh Components in a
similar manner, as outlined in steps 14 thru 18.

Optional “PassThru” Connections:

21. Connect Balanced Cables from the A/V Control
Center Front Left and Right Channel Balanced
Output connectors to the BALanced 2 Input con­nectors.

Note: Refer to Setup “PassThru” on page 15 to activate

the BALanced 2 Input.

22. Connect a Control Cable from the C48
PASSTHRU to A/V Control Center Zone ZA
Power Control Output.

Optional USB Connection:

23. Connect a USB cable with (type A to type B) con­nectors from the C48 USB D/A Input to an avail­able USB connector.

Ground Connections:

24. Connect the Ground Cable coming from the Turn­table to the C48 GND Binding Post.

AC Power Cords Connections:

25. Connect the C48 and any remaining components’
AC Power Cords to a live AC outlet as illustrated.

9