McIntosh C28 Service Manual

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Ultlniush

028

PREA MPL IF IER

SERVICE INFORMATION

FROM SERIAL NO. IOXOI T0 9IX49

McINTOSH LABORATORY INC. 2 CHAMBERS STREET BINGHAMTON, NEW YORK

82)

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C28

ELECTRICAL SPECIFICATIONS

FREQUENCY RESPONSE

+0 to 0.5 dB from 20 Hz to 20,000 Hz.

DISTORTION

Less than 0.1% at each output at rated output level, 20 Hz
to 20,000 Hz.

INPUT SENSITIVITY AND IMPEDANCE

Phone I and Phone 2
2 millivolts at H7k Ohms (1,000 Hz)

Aux, Tuner, Tape I and Tape 2
0.25 volts at 250k ohms

Microphone
2,5 millivolts at 500k ohms

Tape Head
2 millivolts at Book ohms (500 Hz)

HUM AND NOISE

Aux, Tuner, Tape I and Tape 2
90 dB below rated output

Phono I, Phone 2 and Tape Head
78 dB below l0 millivolt input, equivalent to less than
I.Z microvolts at the input terminals.

Microphone
Less than l.5 microvolts at the Input terminals.

OUTPUT LEVEL AND IMPEDANCE

Main Output
2.5 volts with rated input. less than l00 ohms source
impedance, to operate into H7k ohm or greater load.

Tape Output
0.25 volts with rated input. Less than ISO ohm source
impedance. to operate into 07k ohm or greater load.

Headphone/Line Output
0.75 volts into 8 ohm load or 3.0 volts into 600 ohm
line. Less than 0.2 ohms source Impedance. Level
controls provided.

Center Channel
0.7 volts with rated input to both channels. Level
control provided.

BASS CONTROL TREBLE CONTROL

+

:20 dB at 20 Hz. :IB dB at 20,000 Hz.
L.F. FILTER

Flat or roll off below 50 Hz, active filter l2 dB/0ctave
down I8 dB at 20 Hz.

H.F. FILTER

Flat or roll off above 7,000 Hz, active Filter lZ dB/octave
down 20 dB at 20,000 Hz.

POWER REQUIREMENT

ll7 volts, 50/60 Hz, M5 watts.