User manual MCINTOSH MC2120

[. . . ] THE MCINTOSH MC 2120 SOLID STATE STEREO POWER AMPLIFIER R e a d i n g Time: 29 M i n u t e s Price $1. 25 Your MC 2120 Stereo Power Amplifier will give you many years of pleasant and satisfactory performance. If you have any questions, please contact: CUSTOMER SERVICE Mclntosh Laboratory Inc. 2 Chambers Street Binghamton, New York 13903 Phone: 607-723-3512 Contents SERVICE . 12 WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE. Take Advantage of 3 years of FREE Service . . . [. . . ] Generally, these waveform differences are the result of applying voltages at the input in excess of its rating. Because the limit indicator circuit can show an overload condition as short as one cycle of a 20, 000 Hz signal a holding circuit keeps the red indicator on long enough for the eye to see. HEADPHONES The output of the front panel HEADPHONE jack has been designed to feed low impedance dynamic stereo headphones. Electrostatic headphones generally require higher power than dynamic headphones. Connect them to the LEFT and RIGHT OUTPUT contacts on the back of the MC 2120. Plug dynamic headphones into the front panel HEADPHONE jack. Adjust the front panel LEFT GAIN and RIGHT/MONO GAIN control for comfortable headphone listening. POWER The power switch turns the MC 2120 ON or OFF. The switch does not control the power outlet on the back panel. If you wish to control the AC power from a preamplifier control center leave the switch in the ON position. Be sure the AC cord of the MC 2120 is plugged into the controlled outlets on the rear of the preamplifier control center. OFF: In the OFF position the AC power to the amplifier is turned off. 9 Rear Panel Information LEFT and RIGHT OUTPUT For stereo operation, output impedances of 2, 4, 8 and 16 ohms have been provided on a secure, screw type barrier strip. For monophonic operation proper interconnection provides, 1, 2, 4 and 8 ohms from the same barrier strips. When the instrument is properly connected the MODE switch is used to select the method of operation desired. INPUT In the stereo or twin amplifier mode of operation both input jacks accept signal. In the mono mode of operation the Left channel input jack is disconnected and only the Right (MONO) channel input jack accepts signal. POWER GUARD Amplifiers are capable of delivering large quantities of power when they are driven to clipping. Clipping is caused when the amplifier is asked to produce more power output than it can deliver with low distortion. A clipped amplifier can have more than 40% harmonic distortion. The extra energy content of the clipped signal will damage most speakers. A new Mclntosh advancement helps to protect your speaker from this kind of damage. The MC 2120 has a built in "waveform comparator" that compares the wave shape of the input signal with the output signal. If the non-linearity between the two signals exceeds 0. 5% a front panel signal illuminates in red (LIMIT). POWER OUTPUT STEREO watts per channel from 20 Hz to 20, 000 Hz, both channels operating MONO 0. 1% maximum harmonic distortion at any power level from 250 milliwatts to 240 watts from 20 Hz to 20, 000 Hz INTERMODULATION DISTORTION STEREO 0. 1% maximum if instantaneous peak power output is 240 watts or less per channel with both channels operating for any combination of frequencies, 20 Hz to 20, 000 Hz MONO 0. 1% maximum if instantaneous peak power output is 480 watts or less for any combination of frequencies, 20 Hz to 20, 000 Hz FREQUENCY RESPONSE (at one watt output) 20 Hz to 20, 000 Hz, +0 -0. 25 dB 10 Hz to 100, 000 Hz +0 -3. 0 dB NOISE AND HUM 95 dB below rated output RATINGS OUTPUT VOLTAGES 25 volts for distribution lines DAMPING FACTOR STEREO 16 at 2 ohms output, 50 at 4 ohms output, 20 at 8 ohms output, 14 at 16 ohms output MONO 16 at 1 ohm, 50 at 2 ohms, 20 at 4 ohms, and 14 at 8 ohms output INPUT IMPEDANCE 100, 000 ohms INPUT SENSITIVITY Switchable: 0. 75 volt or 2. 5 volts--Level control provided for higher input voltages. [. . . ] The Mclntosh patented Sentry Monitoring circuit constantly monitors the output signal and instantly reacts to prevent overload of the output transistors. At signal levels up to rated output this circuit has high impedance and has no effect upon the output. If the power output exceeds design maximum, the Sentry Monitoring circuit operates to limit the signal to the output transistors. In the event of a short circuit across the amplifier output or severe impedance mismatch the Sentry Monitoring circuit will protect the output transistors from failure. [. . . ]