User manual MCINTOSH MC2125

[. . . ] THE MclNTOSH MC 2125 SOLID STATE STEREO POWER AMPLIFIER Reading Time: 31 Minutes Price $1. 25 Your MC 2125 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 . . . [. . . ] 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 2125 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). With the POWER GUARD switch in the NORMAL position, 1. 0% distortion will cause the POWER GUARD circuit to operate. The POWER GUARD circuit limits the input dynamically so that the amplifier cannot be overdriven which eliminates amplifier output clipping. MODE SWITCH The MC 2125 can be used in these different manners: stereo (or as a twin amplifier) and mono. Because of the excellent channel separation of the MC 2125, it can fulfill all of these functions. When the outputs are 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. INPUT LEVEL The input sensitivity of the MC 2125 is 0. 75 volts or 2. 5 V depending on the position of the INPUT LEVEL switch. With indicated voltage applied, the amplifier will deliver its rated power. 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, always have the INPUT LEVEL switch in the 2. 5 V position and the front panel LEFT and 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 The MC 2125 is rated for 120 volts, 50/60 hertz. It uses 50 watts when there is no signal output and 460 watts with both channels delivering rated power. An 8 ampere fuse protects the MC 2125 electrically. An auxiliary AC power outlet has been provided. The auxiliary outlet is neither fused nor switched. 10 Performance Limits and Ratings PERFORMANCE GUARANTEE Performance Limits are the maximum deviation from perfection permitted for a Mclntosh instrument. [. . . ] METER CIRCUIT The meter circuit has three basic sections: the logarithmic amplifier, full wave rectifier, and DC amplifier. In the WATTS ranges, the logarithmic amplifier is used. In the DECIBEL ranges, the signal goes directly to the full wave rectifiers through an attenuator which is selected by the METER RANGE switch. The logarithmic amplifier consists of a high gain operational amplifier with a bipolar connected silicon diode pair as feedback elements. These diodes have a uniform logarithmic characteristic over an 80 dB range. [. . . ]