McIntosh C-33 Owners manual

THE MclNTOSH C 33 SOLID STATE STEREO PREAMPLIFIER

Reading Time: 43 Minutes

Price $2.00

VARIOUS REGULATORY AGENCIES REQUIRE THAT WE BRING THE FOLLOWING
INFORMATION TO YOUR ATTENTION. PLEASE READ IT CAREFULLY.

WARNING: TO PREVENT FIRE OR SHOCK

HAZARD, DO NOT EXPOSE THIS UNIT TO
RAIN OR MOISTURE.

The Mclntosh you have purchased is a Model C 33. It

has a serial number located on the rear panel of the

chassis. Record that serial number here:

Serial Number

The model, serial number and purchase date are im-

portant to you for any future service. Record the pur-

chase date here:

Purchase date

Upon application, Mclntosh Laboratory provides a
Three-Year Service Contract. Your Mclntosh Authorized
Service Agency can expedite repairs when you provide

the Service Contract with the instrument for repair. To
assist, record your Service Contract number here:

Service Contract Number

Your C 33 Stereo Preamplifier is designed
to perform to its specifications
for many years. If you
have any questions, please contact:

CUSTOMER SERVICE

Mclntosh Laboratory Inc.

2 Chambers Street

Binghamton, New York 13903-9990
Phone: [phone]

Take Advantage of 3 years
of Contract Service...

Fill in the Application NOW.

Contents

INTRODUCTION 2

SIMPLIFIED BLOCK DIAGRAM 3

INSTALLATION 4

SIMPLIFIED CONNECTING DIAGRAM 6

HOW TO CONNECT 7

USING THE FRONT PANEL CONTROLS 12

USING THE PUSHBUTTONS 15

TOP PANEL INFORMATION AND

SECONDARY CONTROLS 17

PERFORMANCE LIMITS AND RATINGS 18

PERFORMANCE CHARTS 19

TECHNICAL DESCRIPTION 22

BLOCK DIAGRAM 24

MclNTOSH THREE YEAR SERVICE CONTRACT

An application for A THREE YEAR SERVICE CONTRACT is included with this manual.

The terms of the contract are:

1. Mclntosh will provide all parts, materials
and labor needed to return the measured
performance of the instrument to the
original performance limits. The SER­VICE CONTRACT does not cover any
shipping costs to and from the authoriz­ed service agency or the factory.

2. Any Mclntosh authorized service agency
will repair Mclntosh instruments at nor­mal service rates. To receive service
under the terms of the SERVICE CON-

TRACT, the SERVICE CONTRACT CER­TIFICATE must be presented when the

instrument is taken to the service agency.

3. Always have service done by a
Mclntosh authorized service agency. If
the instrument is modified or damaged
as a result of unauthorized repair, the

SERVICE CONTRACT will be cancelled.

Damage by improper use or mishandl­ing is not covered by the SERVICE
CONTRACT.

4. The SERVICE CONTRACT is issued to

you as the original purchaser. To pro­tect you from misrepresentation, this

contract cannot be transferred to a se­cond owner.

5. To receive the SERVICE CONTRACT,
your purchase must be made from a

Mclntosh franchised dealer.

6. Your completely filled in application for
the SERVICE CONTRACT must be post­marked within 30 days of the date of
purchase of the instrument.

7. To receive the SERVICE CONTRACT, all
information on the application must be
filled in. The SERVICE CONTRACT will
be issued when the completely filled in
application is received by Mclntosh
Laboratory Incorporated in Binghamton,

New York.

8. Units in operation outside the United
States and Canada are not covered by
the Mclntosh SERVICE CONTRACT, re­gardless of the place of purchase. Nor
are units acquired outside the U.S.A.
and Canada, the purchasers of which
should consult with their dealer to
ascertain what, if any, service contract
or warranty may be available locally.

Copyright 1982 © by Mclntosh Laboratory Inc.

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Introduction

The Mclntosh C 33 is a super quality, high perfor­mance Stereo Preamplifier. Its design has been
governed by insistence on great flexibility, versatili­ty, low distortion and high performance with long
life.

The C 33 provides many features for your listening
enjoyment. They include:

1. a dual preamplifier system with separate listen

and record program lines, which allows listening
to one program source while recording from a dif­ferent independent program source.

2. a low noise electronic input switching system,
which uses dual field effect transistors (FETs) and
short signal leads to give great source to source

isolation, low distortion, and freedom from noise

and hum pickup.

3. two, seven source, input selector switches for 3
tape decks, 2 turntables, 1 tuner, and 1 auxiliary,
which allow independent source selection for

listening and recording.

4. an electronic record monitor switch, which
allows the record program line to be heard
through the main listen output.

5. a five band program equalizer, which permits
the adjustment and improvement of the loudness
contrast of the five most important frequency
ranges. Each band can be emphasized or de­emphasized to satisfy your listening taste. The
program equalizer can be switched to either the
listen or record program lines. This allows
equalizing the record output signal to tape
recorders or equalizing the main listening output.

6. a precision volume control, which is electroni­cally trimmed during manufacture to maintain
channel to channel accuracy to better than 1
decibel (dB). This high order of accuracy assures
continuing program balance as the listening
volume is changed.

7. an active circuit loudness control, which is
electrically independent of the volume control.
Close conformity to the Fletcher-Munson equal
loudness curves can be attained regardless of the
volume control position.

8. high and low frequency filters, which reduce
high frequency noise and low frequency rumble at
a 12 dB per octave roll off rate.

9. a compandor, which permits expansion or com­pression of the dynamic range of program mater­ial from either the record tape output or the main
listen output. Compressed recordings and broad­casts can be expanded on playback to restore
their dynamic range. Tapes can be recorded using
compression and replayed using expansion to in­crease signal-to-noise ratio.

10. front panel tape recorder jacks, which allow
simple plug-in of an additional tape recorder
without disconnecting your regular system. This
makes tape copying to a portable recorder very
convenient.

11. a tape recording program line, which makes it
very easy to record phono, tuner, or auxiliary on
up to 3 recorders at the same time (4 recorders
when using the front panel tape recorder jacks) or

to copy from recorder to recorder. Recording
operations do not interfere with the separate

listen program line.

12. an automatic AC power control circuit, which

can conveniently turn off the entire stereo system
when the turntable turns off.

13. a built-in monitor amplifier, which provides 20

watts per channel power output and includes the

Mclntosh patented Power Guard protection cir­cuit. The monitor amplifier can be operated from
the listen program line, the record program line, or

independently from a separate external source.

14. two front panel headphone jacks, which are
powered by the internal monitor amplifier.

15. two speaker output pushbuttons, which control

the operation of two sets of loudspeakers (when

used with the optional SCR-2 speaker control
relay) or two sets of power amplifiers.

16. electronically regulated power supplies, which

maintain stable operation even during periods of

low line voltage.

This outstanding preamplifier will serve you best
when you understand its functions and what it is de­signed to do. Some time invested with this manual
will be valuable in your knowledge of how it works.
The simplified block diagram on page 3 shows how
the C 33's internal circuits are arranged. The simpli­fied connecting diagram on page 6 shows how other
components are connected to the C 33.

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Identical

Diagram

Block

Shown, Other Channel

Channel
One

Simplified

STEREO PREAMPLIFIER

C 33

MclNTOSH

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The PANLOC system of installing equipment con-

veniently and securely is a direct result of Mclntosh

research. By depressing the two PANLOC buttons
on the front panel, the instrument can be either lock­ed firmly in place or it can be unlocked so that the
chassis can slide forward, giving you easy access to
the top and rear panels.

The trouble-free life of an electronic instrument is
greatly extended by providing sufficient ventilation
to prevent the build-up of high internal temperatures
that cause deterioration of component parts. You
should allow enough clearance so that cool air can
enter at the bottom of the cabinet and be vented

from the top. With adequate ventilation the instru­ment can be mounted in any position. The recom-

mended minimum space for installation is 15 inches
(38.1 cm) deep, 17 inches (43.2 cm) wide, and 6 in­ches (15.2 cm) high.

To install the instrument in a Mclntosh cabinet,
follow the instructions that are enclosed with the
cabinet. For any other type of installation, follow
these instructions:

1. Unpack from Carton

Open the carton and remove the PANLOC brackets,

hardware package, and mounting template. Remove
the C 33 from its plastic bag and place it upside
down on the shipping pallet, then unscrew the four
plastic feet from the bottom of the chassis.

2. Mark the Cabinet Panel

Place the mounting template in the position on the
cabinet panel where the instrument is to be install­ed, and tape it in place. The broken lines that repre­sent the outline of the rectangular cutout also repre­sent the outside dimensions of the chassis. Make
sure these lines clear shelves, paritions, or any
equipment. With the template in place, first mark the
six A and B holes and the four small holes that
locate the corners of the cutout. Then, join the four
corner markings with pencil lines using the edge of
the template as a straight edge.

3. Drill Holes

Use a drill with a 3/16 inch (5 mm) bit held perpen­dicular to the panel and drill the six A and B holes.

Then, using a drill bit slightly larger than the tip of

your saw blade, drill one hole at each of two diago­nally opposite corners. The holes should barely
touch the inside edge of the penciled outline. Before

taking the next step, make sure that the six A and B
holes have been drilled.

4. Saw the Panel Cutout
Saw carefully on the inside of the penciled lines.
First make the two long cuts and then the two short
cuts. After the rectangular opening has been cut out,

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use a file to square the corners and smooth any ir­regularities in the cut edges,

5. Install the Mounting Strips

In the hardware package you will find two mounting
strips and two sets of machine screws. For panels
that are less than ½ inch (12.7 mm) thick, use the ¾
inch (19.1 mm) screws; for panels that are more than
½ inch (12.7 mm) thick, use the 1¼ inch (31.8 mm)
screws.

Starting at the right-hand side of the panel, insert
a screw of proper length into the center hole in the
panel, marked B on the template. On the back of the
panel, align a mounting strip with the holes in the
panel and tighten the screw in the center hole until
the screwhead is pulled slightly into the wood.

Repeat this procedure to attach the mounting
strip to the left side of the panel.

6. Attach the PANLOC Brackets
Using two screws of proper length in the A holes on

each side, attach the PANLOC brackets to the cabi-

net panel; the short flange is mounted against the
front (face) of the cabinet panel. The screws pass
through the PANLOC bracket flange, the cabinet
panel, and then through the mounting strips
previously mounted.

7. Install the Instrument
Guide the AC power cord through the panel opening

to the back of the cabinet; then, slide the instrument

into the opening carefully so that the rails on the

bottom of each side of the chassis engage the
tracks on the mounting brackets. Continue to slide
the instrument into the cabinet until it is stopped by
the adjust position latches. Press the latches in­ward, this permits the instrument to slide into the

cabinet until its front panel is flush with the cabinet

panel. Depress the PANLOC buttons at the lower left
and right corners of the instrument panel to lock the
unit firmly in the cabinet. Depressing the PANLOC
buttons again will unlock the instrument so that it
can slide forward to the adjust position; if you press

inward on the adjust position latches then you can

remove the instrument from the cabinet.

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Simplified Connecting Diagram

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How to Connect

Rear panel input jacks are provided for 2 stereo
turntables, PHONO 1 and PHONO 2; a stereo tuner,
TUNER; 3 stereo tape recorders, TAPE 1, TAPE 2,
and TAPE 3; and an auxiliary high level source, AUX.

Rear panel output jacks are provided to feed 3
stereo tape recorders, TAPE 1, TAPE 2, and TAPE 3;
and 3 stereo 2.5 volt listen program line outputs,

MAIN, OUTPUT 1, and OUTPUT 2. Two sets of jacks,

EXTERNAL PROCESSORS; LISTEN and RECORD,
are provided to connect noise reduction units or
other signal processing devices. Monitor amplifier
EXT INPUT jacks, OUTPUT jacks and speaker ter­minals allow connecting to and from the monitor
amplifier.

CONNECTING TURNTABLES

Connect the cable from the left channel of the
turntable into the Left PHONO 1 INPUT jack. Con­nect the cable from the right channel of the turn­table into the Right PHONO 1 INPUT jack. For a se­cond turntable, connect PHONO 2 in the same way.

The C 33 uses automatic shorting jacks for the

PHONO inputs. If the inputs are not connected,

shorting plugs are not needed.

the Right TAPE 1 INPUT jack. Connect a second and
third recorder in the same manner to the TAPE 2 IN­PUT and TAPE 3 INPUT jacks.

Front Panel Tape Recorder Jacks:

TAPE 3 recorder input and output connections are
also available at the TAPE 3 IN-OUT jacks on the
front panel. When a plug is inserted in the front pan­el TAPE IN jack the circuit to the rear panel TAPE 3
INPUT jacks will be disconnected. Inserting a plug in
the front panel TAPE OUT jacks does not disconnect
the rear panel TAPE 3 OUTPUT. Thus it is possible to
record from the front panel TAPE OUT jack and the
rear panel TAPE 3 OUTPUT jack at the same time but
it is not possible to listen from the corresponding

jacks at the same time. Metal shielded ¼ inch
stereo phone plugs may be used. Connections are
tip: left signal, ring: right signal, and sleeve: com-

mon ground.

CONNECTING AUX

Connect the left channel cable from any high level

source (tuner, TV set, tape recorder, etc.) to the Left
AUX INPUT jack. Connect the right channel cable to
the Right AUX INPUT jack.

CONNECTING A STEREO TUNER

Connect the cable from the tuner left channel out-

put to the Left TUNER INPUT jack.

Connect the cable from the tuner right channel

output to the Right TUNER INPUT jack.

CONNECTING TAPE RECORDERS

To Record:

Connect a cable from the Left TAPE 1 OUTPUT jack
to the left high level input of the tape recorder. Con­nect a cable from the Right TAPE 1 OUTPUT jack to
the right high level input of the tape recorder. Con­nect a second and third recorder in the same manner
to the TAPE 2 OUTPUT and TAPE 3 OUTPUT jacks.

To Playback/Monitor:

Connect a cable from the tape recorder left chan­nel output to the Left TAPE 1 INPUT jack. Connect a

cable from the tape recorder right channel output to

CONNECTING EXTERNAL PROCESSORS

There are two sets of EXTERNAL PROCESSOR
jacks. One set is for LISTEN program lines and one
set is for RECORD program lines. These jacks are
used to connect to and from a noise reduction unit
or to and from any other signal processing device.
Be sure to match left to left and right to right chan­nels when connecting external processors.

When connections are made to the EXTERNAL
PROCESSOR from jacks, the signal path is broken
within the C 33. THE PROCESSOR MUST BE TURN­ED ON FOR THE PROGRAM TO PASS THROUGH
THE SYSTEM.

CONNECTING TO POWER AMPLIFIERS

Connect the MAIN OUTPUT jacks to the input of a

stereo power amplifier. The Left MAIN jack connects

to the amplifier left input jack. The Right MAIN jack

connects to the amplifier right input jack.

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