McIntosh MC1.2KW Technical Description, Design Philosophy, Block Diagram of the Power Amplifier

Figure 13

Technical Description

cies is less than 0.002%. The true distortion readings on the MC1.2KW are so low, it takes special measuring techniques to make accurate readings. The MC1.2KW can deliver the best possible performance from any type of high quality loudspeaker system.

Creating an amplifier with this level of performance did not come easily. Many months of design, testing and mea- suring were required. Extensive controlled listening tests, the ultimate form of measuring, were made before the final design was accepted.

Design Philosophy

The design philosophy incorporated in the MC1.2KW involved several different techniques, all based on sound scientific logic. Every stage of voltage or current ampli- fication must be as linear as possible prior to the use of negative feedback. McIntosh engineers know how to prop- erly design negative feedback circuits so they contribute to the extremely low distortion performance expected from a McIntosh amplifier. The typical McIntosh owner would never accept the approximately 100 times higher distortion of many non-feedback designs.

Double Balanced Push-Pull design is used from input to output. Each half of the amplifier contains complimentary balanced circuitry. The resulting double balanced configu- ration cancels even order distortion. Refer to figure 12.

All transistors are selected to have nearly constant current gain over the entire current range they must cover. Output transistors in particular, have matched uniform current gain, high current bandwidth product and large

active region safe operating area. An automatic tracking bias system completely eliminates any trace of crossover distortion. Precision metal film resistors and low dielectric absorption film capacitors are used in all critical circuit locations.

The output signals of the two balanced circuits are

coupled together in the unique McIntosh MC1.2KW Out- put Autoformer. It provides low distortion power transfer at frequencies from below 20Hz to well beyond 20,000Hz with optimum impedance points of two ohms, four ohms and eight ohms. The unequaled expertise of McIntosh in the design and manufacturing of autoformers is legendary in the high fidelity industry.

The high ef- ficiency circuit de- sign of the MC1.2KW contrib- utes to low operating tempera- tures. More than 2800 square inches of heat sink

area keep the MC1.2KW operating safely with convection cooling. No fans are needed. Refer to figure 13.

Block Diagram

of the

Power Amplifier

(one channel shown)

Figure 12

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