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 . . . [. . . ] 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. 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. 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. GENERAL INFORMATION POWER REQUIREMENTS 120 volts 50/60 Hz, 50 watts at zero signal output, 460 watts at rated output SEMICONDUCTOR COMPLEMENT 39 silicon transistors 24 silicon rectifiers and diodes 2 integrated circuits MECHANICAL INFORMATION SIZE Front panel measures 16 inches wide (40. 7 cm) by 5 7/32 inches high (13. 2 cm). Chassis measures 14 5/8 inches wide (37. 2 cm) by 5 inches high (12. 7 cm) by 13 inches deep (33 cm), including connectors. Knob clearance required is 1 1/2 inches (3. 8 cm) in front of mounting panel FINISH Front panel is anodized gold. Chassis is chrome and black WEIGHT 57 pounds (25. 9 kg) net, 70 pounds (31. 8 kg) in shipping carton 120 watts minimum sine wave continuous average power output per channel, both channels operating into 2 ohms, 4 ohms, 8 ohms, or 16 ohms load impedance, which is: 15. 5 volts RMS across 2 ohms 21. 9 volts RMS across 4 ohms 31. 0 volts RMS across 8 ohms 43. 8 volts RMS across 16 ohms MONO 240 watts minimum sine wave continuous average power output into 1 ohm, 2 ohms, 4 ohms, or 8 ohms load impedance, which is: 15. 5 volts RMS across 1 ohm 21. 9 volts RMS across 2 ohms 31. 0 volts RMS across 4 ohms 43. 8 volts RMS across 8 ohms OUTPUT LOAD IMPEDANCE STEREO 2 ohms, 4 ohms, 8 ohms, and 16 ohms; separate terminals are provided for each output MONO 1 ohm, 2 ohms, 4 ohms, and 8 ohms; obtained by connecting together the appropriate terminals of both channels RATED POWER BAND 20 Hz to 20, 000 Hz TOTAL HARMONIC DISTORTION STEREO 0. 1% maximum harmonic distortion at any power level from 250 milliwatts to 120 11 Per Channel Both Channels Operating HARMONIC DISTORTION AT RATED OUTPUT Performance Charts FREQUENCY RESPONSE AT 1 WATT OUTPUT POWER BANDWIDTH AT 0. 1% THD 12 OUTPUT SIGNAL WAVEFORM SHOWING ACTION OF POWER GUARD TO ELIMINATE OUTPUT SIGNAL CLIPPING. [. . . ] The autotransformer also protects speakers from damage in the event of amplifier failure. Should a direct current component appear in the output it is shunted by the autotransformer and cannot damage the speaker. 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. [. . . ]