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.
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