User manual MCINTOSH MC2255

[. . . ] THE MclNTOSH MC 2255 SOLID STATE STEREO POWER AMPLIFIER Reading Time: 31 Minutes Price $2. 00 VARIOUS REGULATORY AGENCIES REQUIRE THAT WE BRING THE FOLLOWING INFORMATION TO YOUR ATTENTION. PLEASE READ IT CAREFULLY. WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE. The Mclntosh you have purchased is a Model MC 2255. It has a serial number located on the rear panel of the chassis. Record that serial number here: Serial Number The model, serial number and purchase date are important to you for any future service. [. . . ] If a circuit should fail, the red "limit" lights will come on and the sequence will stop at that point. Speaker turn on will not occur until the fault has been corrected; thereby protecting your system from any further damage. There are two user controls associated with the auto test circuit. They are located on the amplifier top panel. Two switches control the speed of the countdown (SLOW or FAST) and the presence of the beep tone (ON-OFF). 10 ON: Music will be heard through the loudspeakers. Use this as the normal listening position. Rear Panel information MODE SWITCH The MC 2255 will operate in three modes, Stereo, Mono Bridge, and Mono Parallel. The Mono modes differ in the loads they will drive and the connection sequence to the speaker terminals. LEFT and RIGHT OUTPUT TERMINALS RIGHT/MONO GAIN controls in the fully clockwise position. If more gain is desired the 0. 75 V position may be used. For source equipment other than Mclntosh, set the switch in the position nearest to the stated output rating of the source equipment. AC POWER For stereo operation, output impedances of 1, 2, 4 and 8 ohms have been provided on a secure, screw type barrier strip. For monophonic operation proper interconnection provides 0. 5, 1, 2, 4, 8, and 16 ohms from the same barrier strips. See page 5 for connecting instructions. INPUT JACKS The input to the MC 2255 is 120 volts 50/60 Hz at up to 12 amps. The primary circuit is protected by a 15 Amp Fuse. In the stereo mode of operation, both input jacks accept signal. In the mono mode of operation only the Right (MONO) channel input jack accepts signal and the Left channel input jack is disconnected. INPUT LEVEL The Input sensitivity of the MC 2255 is 0. 75 volts or 2. 5 V depending on the position of the INPUT LEVEL switch. All Mclntosh preamplifiers have been designed to deliver 2. 5 volts output with rated input. For the best signal to noise ratio when using Mclntosh source equipment, place the INPUT LEVEL switch in the 2. 5 V position and the front panel LEFT and 11 Performance Limits PERFORMANCE GUARANTEE Performance Limits are the maximum deviation from perfection permitted for a Mclntosh instrument. We promise you the MC 2255 you buy must be capable of performance at or exceeding these limits or you get your money back. Mclntosh is the only manufacturer that makes this guarantee. level from 250 milliwatts to 500 watts from 20 Hz to 20, 000 Hz. INTERMODULATION DISTORTION STEREO 0. 02% maximum if instantaneous peak power output is 500 watts or less per channel with both channels operating for any combination of frequencies, 20 Hz to 20, 000 Hz. MONO 0. 02% maximum if instantaneous peak power output is 1000 watts or less for any combination of frequenices, 20 Hz to 20, 000 Hz. FREQUENCY RESPONSE (at one watt output) 20 Hz to 20, 000 Hz + 0 - 0. 25 dB. [. . . ] The outputs of the rectifiers are combined at the operational amplifier output, so the highest signal, either positive or negative, is the one that is indicated by the meters. Gate diodes are used to charge a low leakage capacitor which attains and holds a charge during signal peaks. The operational amplifier provides a large amount of current so the capacitor can charge suddenly. The charge on the peak holding capacitor is amplified in a two transistor DC amplifier which is used to drive the meter. [. . . ]