McIntosh c22 User Manual

STEREO

PREAMPLIFIER

C22

CONTENTS

GENERAL DESCRIPTION
TECHNICAL DESCRIPTION

Mechanical Specifications
Electrical Specifications

FRONT PANEL INFORMATION
INSTALLATION
CONNECTIONS

AC Connections
AC Power
Input Connections
Output Connections
Loudspeaker Phasing Connections
Ground Connection

OPERATING INSTRUCTIONS
GUARANTEE
3-YEAR FACTORY SERVICE CONTRACT

1

1
2
2

3
8

8
8

9
9

10
11

11
11

16
16

OWNER'S MANUAL

C 22

C22 STEREO PREAMPLIFIER

GENERAL DESCRIPTION

The Mclntosh C22 Stereophonic Pream­plifier is a control center for any stereophonic
sound system. To increase your enjoyment of
stereo, this control center does four jobs with
precise control.

First, the control center amplifies weak
electrical impulses. As the record rotates on

the turntable, undulations in the grooves
move the pickup stylus approximately one
thousandth of an inch, in any direction, from
the rest position. From this slight mechanical

movement, the pickup stylus generates a
weak electrical impulse on the order of a few
thousandths of a volt. To amplify and pre­serve the information in such an electrical
impulse, the finest amplifier performance is
required.

Second, every sound system is used in a
different acoustical environment. The tone
balance of the music is affected by variations
in environment. Also, people listening to the
music have varying ideas of correct tone bal­ance. To compensate for these conditions, a
high-quality tone control center is needed.

Third, all stereophonic and monophonic
records, both domestic and foreign, are
recorded with specific frequency equaliza­tion. The control center must accurately com­pensate for this equalization introduced in

the recording process.

Fourth, programs can originate from sev­eral sources such as tuners, records, tape
machines, microphones, etc. A control center
is needed to select and switch these sources

separately or in combination.

All of these jobs are performed with excel-

lence by the C22.

The C22 also uses the new, exclusive

Mclntosh PANLOC method of installation.
The PANLOC system gives you absolute ease
of installation, operation, and maintenance.

PANLOC is the first professional installation
technique to be used on stereo instruments.

In the PANLOC system a metal shelf is

mounted first, then the preamplifier slides

into position on this shelf. Depressing the

PANLOC buttons on the front panel locks the

preamplifier firmly into place for normal
operation. To unlock the preamplifier, de-

press the front panel PANLOC buttons a

second time. The preamplifier can now slide

forward to the ADJUST position. The pre-

amplifier will lock in this position approxi-

mately 3 inches from the mounting panel.

Now you can adjust the output level controls,

low frequency trim controls, tape equaliza-

tion controls, phase switch and pilot lamp

intensity switch. These controls are mounted
just behind the C22 front panel. Depressing
the ADJUST position holding latches on the

sides of the chassis allows the preamplifier

to be taken out of the PANLOC shelf, or to

slide back into position against the mounting

panel.

Once you have enjoyed the outstanding

performance of the C22, you will understand

why Mclntosh products have earned their

reputation as "THE BEST." Your Mclntosh
C22 Stereophonic control preamplifier will
give you years of the finest possible perform­ance, and will become a highly valued part of

your home music system.

TECHNICAL DESCRIPTION

The C22 Stereophonic Preamplifier com­bines excellence in performance with ease of
operation. The most often used controls have
large diameter knobs. A new type of rocker
switch is used for the controls with simple

on-off functions. The C22 has an illuminated
front panel with a light intensity switch to

provide convenient reading under low-level
lighting conditions. The Mode and Input
Selector switch positions are also illuminated.

The C22 circuit consists of 3 amplifier

sections in duplicate for the left and right

stereo channels together with a common
power supply. The first amplifier section is

1

the input preamplifier used to amplify and
equalize signals from phonograph pickups,
microphones or tape heads. Skillful circuit
layout, proper grounding, and adequate
shielding reduce the hum so low it is virtually
unmeasurable. Extreme care in manufactur­ing combined with low noise tubes, high
specific resistivity circuit boards, metal film
and wire wound resistors achieves new low in
residual noise.

The second amplifier section follows the
main volume control, making it impossible to
overload the high level input circuits or any
following circuits. The same design tech­niques as used in the preamplifier section
assure low noise and hum. The BASS and
TREBLE feedback-type tone controls operate
in connection with this amplifier section. The
controls are switch-type with approximately

4 db change per step. Exceedingly low distor­tion and precise control of frequency re­sponse contours are assured using this

arrangement.

Front panel tape jacks are provided for

convenient use of an external tape machine.

The TAPE JACK switch connects the jacks for

either playback or recording through the C22.

The third section is the cathode follower

output. The sharp cutoff (18 db per octave)

RUMBLE and HF (high frequency) filters are

associated with this section. OUTPUT LEVEL
controls are located at the inputs of the cath­ode followers to allow simple balance of the
entire amplifier-speaker system. The OUT-

PUT LEVEL controls are located on top of the
C22, behind the front panel. These controls
are conveniently accessible by releasing the

PANLOC buttons and sliding the C22 out to
the adjust position.

The power supply deserves special men­tion. The power transformer is constructed
with "core" type grain oriented laminations
and magnetic shielding for low external hum­fields. Long life rectifiers with full wave
rectification, filter condenser sectionalizing
and careful grounding add to the hum-free
long life characteristics of the C22.

Special attention has been given to the
mechanical design. The PANLOC system is
the first professional installation technique
to be used on stereo instruments. The

PANLOC system gives you absolute ease of
installation, operation and maintenance. The
C22 may be conveniently installed in furni­ture cabinets, custom-built installations, pro­fessional relay racks or an attractive finished
Mclntosh cabinet.

MECHANICAL SPECIFICATIONS

Size:

Front panel; 16 inches wide by 57/16 inches

high; chassis (including PANLOC shelf) 15
inches wide by 5 inches high by 13 inches
deep, including connectors; clearance in
front of mounting panel including knobs,

1½ inches.

ELECTRICAL SPECIFICATIONS

Power Requirement:

117 volts 50/60 cps AC, 34 watts.

Input Sensitivity and Impedance:

Auxiliary, Tape, Tuner 1, and Tuner 2: 0.25

volts, 250,000 ohms.

Phono 1 and Phono 2: 2 millivolts, 47,000

ohms.

Microphone: 2.5 millivolts, 1 megohm.
Tape Head: 2 millivolts, 1 megohm.
Tape Compare: 0.25 volts, 250,000 ohms.

Weight:

16 pounds net, 25 pounds in shipping carton.

Finish:

Anodized gold and black (front panel).

Frequency Response:

±0.5 db from 20 cps to 20,000 cps.

Distortion:

Less than 0.2% at 10 volts output.
Less than .02% at 3 volts output.

Total Noise:

High Level Inputs: 85 db below rated output.
Low Level Inputs: Less than 1.5 microvolts at

input terminals.

2

Main Output:

2.5 volts with rated input.

Tape Output:

.25 volts with rated input.

Left Plus Right Output:

1 volt from generator impedance of 25,000

ohms.

Voltage Amplification:

Auxiliary, Tape, Tuner 1, and Tuner 2:

To Main Output, 20 db (10 to 1).

To Tape Output, 0 db (1 to 1).

Phono 1 and Phono 2 (At 1 KC):

To Main Output, 62 db (1250 to 1).
To Tape Output, 42 db (125 to 1).

Microphone:

To Main Output, 60 db (1000 to 1).
To Tape Output, 40 db (100 to 1).

Tape Head (At 500 cps):

To Main Output, 62 db (1250 to 1).

To Tape Output, 42 db (125 to 1).

A.C. Outlets:

1 unswitched (Red) for turntable or tape

machine.

4 switched.

Tubes:

6 each 12AX7.

Tape Jack Switch:

2 position, connects panel jacks to allow

signals to be fed from or to the C22 to
record or playback using an external
portable tape recorder.

Bass Controls:

Separate channel 11 position switch type,

±20 db at 20 cycles.

Treble Controls:

Separate channel 11 position switch type,

± 20 db at 20,000 cycles.

Compensator Switch:

RIAA or LP record equalization.

Tape Switch:

Normal, or Tape Monitor.

Rumble Filter:

50 cps cutoff.

HF Filter:

5000 cycle cutoff.

Additional Set-Up Controls:

The following controls are located behind the

front panel on the top of the C22 chassis.
These controls are readily accessible by
depressing the PANLOC buttons to slide
the C22 forward from the mounting panel:

Output Level Controls (L, L + R, and R):

Allows the balance of the entire system to

be conveniently adjusted.

Low Frequency Trim Controls (L and R):

Allows frequencies below 100 cps to be

boosted up to 6 db to compensate for
unequal speaker response.

Tape Equalization Controls (L and R):

Adjusts tape head input high frequency

response.

Phase Switch:

2 position, normal (0°) or reverse (180°).

Pilot Lamp Intensity Switch:

2 position, bright or dim.

FRONT PANEL FACILITIES

Figure 1. C22 Front Panel.

3

INPUT SELECTOR

Figure 2. INPUT SELECTOR switch.

Select any one of eight program sources

with this switch:

1. AUX: any auxiliary service requiring flat

amplification, such as a television set, is
connected to the C22 through the AUX
position.

2. TAPE: any self-contained tape machine
(tape machine having its own playback
preamplifier) is connected to the C22
through the TAPE position.

3. TUNER 1: AM and FM or MPX FM outputs
from a stereo tuner are connected to the
C22 through the TUNER 1 position.

4. TUNER 2: same as TUNER 1.

5. PHONO 1: connects the C22 for stereo
and monophonic operation for records.

6. PHONO 2: same as PHONO 1.

7. MIC: stereo microphones are connected
to the C22 through the MIC position.

8. TAPE HD: a tape deck that does not con­tain its own playback preamplifier is con­nected to the C22 through the TAPE HD

position.

Use the MODE SELECTOR to:

Listen to normal stereo (4 following
and page 13.

Reverse the left and right arrangement
of musical instruments (3 following
and page 12).

Balance the amplifiers and loudspeak­ers in a stereo system (6 and 7 follow­ing and page 11).

Listen to monophonic sound (1 and 2

following and page 13).

Listen thru both loudspeakers to either
track of a stereo program source (1 and
2 following and page 13).

Turn the MODE SELECTOR to:

1. L TO L & R:

connects

the

"left"

input

to

both loudspeakers.

2. R TO L & R: connects the "right" input to
both loudspeakers.

3.

STEREO

the

REV: connects

"right"

loudspeaker

the

"left"

and the

input

to

"right"

input to the "left" loudspeaker.

4.

STEREO:

connects

the

"left"

input

to the
"left" loudspeaker and the "right" input
to the "right" loudspeaker.

5. MONO (L + R): adds the "left" input and
the

"right"

input

and

then

connects

the

L + R program to both amplifiers and

loudspeakers.

6. L + R TO L: connects the "left plus right"

programs to the "left" loudspeaker only.

7. L -I- R TO R: connects the "left plus right"
programs

VOLUME

to the

"right"

loudspeaker only.

MODE SELECTOR

Figure 3. MODE SELECTOR switch.

4

Figure 4. VOLUME control.

Use the VOLUME control to regulate the

combined volume level of both channels.
Turning the VOLUME control clockwise in­creases volume level.

BALANCE CONTROL

TREBLE CONTROLS

Figure 5. BALANCE CONTROL.

Use the C22 BALANCE control to balance

unequal volume in the left and right channels

of a program source. The volume of each

speaker system relative to the other can be
varied, at the same time their combined
volume level is maintained.

LEFT . . . turning the control to the left
accents the left channel by reducing the right
channel output.

RIGHT . . . turning the control to the right

accents the right channel by reducing the
left channel output.

BASS CONTROLS

Figure 7. TREBLE CONTROLS.

Use the LEFT and RIGHT TREBLE CON­TROLS to regulate treble loudness to the left
and right speakers, respectively. Clockwise

rotation increases treble loudness; counter-

clockwise rotation decreases treble loudness.

Each switch step of the TREBLE Control
changes treble loudness approximately 4 db.

COMP (COMPENSATION)

Figure 8. COMP (COMPENSATION) switch,

Figure 6. BASS CONTROLS.

Use the LEFT and RIGHT BASS CON-

TROLS to regulate bass loudness to the left

and right speakers, respectively. Clockwise
rotation increases bass loudness; counter-

clockwise rotation decreases bass loudness.

Each switch step of the BASS control changes
bass loudness approximately 4 db.

Use the COMP switch to correct for phono
equalization introduced by the recording
process. All current LP and Stereo recordings
use RIAA equalization. Some stereo and
early mono recordings use LP equalization.

TAPE JACKS

Use the C22 TAPE JACKS to hear a pro­gram originating from a portable tape ma­chine or to record a program picked up by the
C22 on a portable tape machine.

RECORD ... . connects signals from the

rear tape jacks to the INPUT SELECTOR

TAPE position. Any program picked up by
the C22 is connected to the portable machine

5