McIntosh MC 225 Owners Manual

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MC225 POWER AMPLIFIER GENERAL DESCRIPTION Over one million watts of amplifier output power capacity have been manufactured by Mclntosh since 1947. In this 1,000,000 watts of audio power there are less than 10 watts of distortion capacity and less than 1/100 watt of noise capacity! The dramatic difference in the quality of music reproduction when you listen through Mclntosh instruments is directly due to low distortion performance. Careful, devoted research is a way of life at Mclntosh. The world's finest amplifier is the creation of per- severing, resourceful Mclntosh engineers. Mclntosh Laboratory is the only manufac- turer in the entire industry to guarantee the lowest distortion at all audio frequencies, at full power. The U.S. Patent Office has rec- ognized the advanced technology of the Mclntosh circuit by granting 6 patents.1 Long life, flexibility, highest quality con- struction are characteristic designs in every Mclntosh instrument. Wide electrical and thermal margins of safety for all components and tubes, advanced engineering, and cool operating design add to the long life built into every Mclntosh product. Reliability pro- longs your investment without expensive maintenance costs. The MC225 has on one chassis two 25 watt power amplifiers. In addition to use as a stereo amplifier, the flexibility of the MC225 permits it to be used as a monophonic amplifier that delivers 50 watts, or as two separate 25 watt amplifiers with each chan- nel amplifying completely separate pro- grams, or as two amplifiers for use with an electronic crossover network. Such flexi- bility permits maximum use for greatest return from your investment. TECHNICAL DESCRIPTION The patented Mclntosh Unity Coupled circuit and output transformer have estab- lished Mclntosh amplifiers as the unchal- lenged leaders in the audio field. Before 1947, low distortion at high power and high efficiency was impossible. A com- pletely new engineering approach resulted in an amplifier that for the first time permitted high power with distortion below 1%. That new engineering produced the Mclntosh Unity coupled circuit and the Mclntosh bifilar wound output transformer. With the intro- duction of the Mclntosh amplifier new stand- ards for distortion-free performance were established. PRIMARY NO 1 turn of primary number one is next to the same turn of primary number two. There is almost complete magnetic coupling between the two wires. The magnetic coupling is rein- forced by the capacitance between the two wires. INPUT OUTPUT PRIMARY NO. 2 Fig. 1 -Representation of bifilar winding. The Mclntosh output transformer is unique. It has two primary windings which are wound bifilarly. In the bifilar technique both primary wires are wound side by side. Each Fig. 2-Representation of Mclntosh output circuit. 'U.S. Patent No's: 2,477,074; 2,545,788; 2,646,467; 2,654,058; 2,860,192; 2,929,028. 1

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