McIntosh C-4 Owners manual

INSTRUCTION MANUAL

MclNTOSH MODEL C-4 and C-4P

AUDIO COMPENSATORS

McINTOSH LABORATORY, INC.

320 Water St. Binghamton, N. Y.

U.S.A.

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INSTRUCTION MANUAL

McINTOSH MODEL C-4 and C-4P

AUDIO COMPENSATORS

The McIntosh Audio Compensator is a complete control unit for profes­sional or home entertainment systems. The Model C-4 derives its power from
any McIntosh power amplifier; the Model C-4P is self-powered.

Five input channels are provided, three of which produce constant ampli­fication over the audio spectrum of 20-20, 000 cycles, one which is compensated
for magnetic phonograph cartridges and one which is compensated for either
magnetic or constant amplitude cartridges. Each input is equipped with a level

control. A three output system is employed, two main outputs where all con­trols are effective and one tape output where only the channel selector and com­pensation selector are effective.

THE AUDIO COMPENSATOR IS A COMPLETE PRE-AMPLIFIER AND
RECORD COMPENSATOR: THEREFORE, THE USE OF AN AUXILIARY
EQUALIZER OR PRE-AMPLIFIER WITH THIS UNIT IS NOT RECOMMENDED.

INSTALLATION OF MODEL C-4 and C-4P

AUDIO COMPENSATORS

The C-4 and C-4P Audio Compensator may be mounted in any type equip­ment cabinet, relay rack panel, door, wall, etc., or in its own cabinet for
chair side operation. It is not necessary to disassemble the Audio Compensator

for mounting. Using the mounting templates provided with this manual, cut a

rectangular hole in the panel to be used for mounting, insert the Audio Compen­sator and secure with wood or machine screws.

When installing the C-4P, the power supply section should be mounted at

least two feet from the Audio Compensator.

After these units have been secured, proceed as follows:

1. Connect speaker to output of power amplifier.

2. Insert power amplifier line cord into one of the Auxiliary A.C. re­ceptacles provided at the rear chassis of the Audio Compensator.

3. C-4: Connect inter-unit cable to socket labeled "PRE-AMP INPUT"
on McIntosh Power Amplifiers. CAUTION: THE INTER-UNIT CABLE
MUST NOT BE REMOVED FROM THE C-4.

C-4P: Insert cable of D-8 power supply into socket labeled
"INTER-UNIT CABLE" on C-4P. Connect audio cable provided between
RETMA pin jack labeled "MAIN OUTPUT" on C-4P and 2.5V input of

power amplifier. (Socket labeled "PRE-AMP INPUT" on McIntosh
power amplifiers.)

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4. The Audio Compensator delivers 2. 5 volts of audio signal at full out­put. The gain control of the power amplifier should be adjusted as out-

lined in the amplifier instruction manual for this sensitivity. (McIntosh
Amplifier Models A-116, MC-30, MC-60, set gain control fully counter
clockwise; 50W-2 and 20W-2 fully clockwise.)

5. Turn the volume control on the Audio Compensator to "OFF".

6. Insert power cord of the Audio Compensator into a 117V., 50/60
cycle power outlet.

7. Turn the Selector Switch on the Audio Compensator to "5" and Bass
control fully clockwise.

8. Turn the volume control on the Audio Compensator clockwise until
the power switch is activated. Allow thirty seconds for warm-up, then

advance the volume control to "10".

9. C-4: Adjust the hum reducing potentiometer on the power amplifier

for minimum hum. C-4P: Adjust the hum reducing potentiometer on

the power supply for minimum hum.

10. Turn the volume control on the Audio Compensator to "OFF".

11. Insert inputs into their proper jacks at the back of the Audio Com-

pensator, and all A.C. power cords into the A.C. outlets provided.

INPUT CONNECTING PROCEDURE

The inherent hum and noise voltages applied to the input of the Audio Com­pensator are -110 DBM, or less than 3 microvolts. To avoid lowering the
signal to hum ratio of the Audio Compensator, by adding hum voltages to the

input, extreme care must be taken in its installation. We offer the following
recommendations as a guide to installation:

1. Connect inputs of Audio Compensator as outlined on the table below.

INPUT

CHANNEL

TAPE

AND

TUNER

MIC

PHONO 1

AND

PHONO 2

FOR USE WITH

Radio or TV Tuners
Tape Recorders

Crystal or Ceramic

cartridges

Crystal Microphones

Low Impedance

Microphone

Phonograph Cart-

ridges (magnetic
or constant
amplitude)

MIN.

60MV

3MV

3MV

MAX.

20V

1V

1V

GAIN

32db

52db

52db

REMARKS

Inputs in excess
of the recom­mended minimum
should be reduced
by the level ad­justments located
on the back panel.
See text for com-

plete operation.

2. The Audio Compensator and magnetic phonograph cartridges should be

mounted at least two feet from power transformers.

3. Inter-unit cables provide a complete ground system. Alternate ground

wires should not be used since they will produce ground loops and increase

the hum level.