McIntosh MCC602TM - Manual (Page 15)

15
Technical Description
McIntosh Laboratory, the company who introduced the
world’s first amplifier over fifty years ago that could be
called “High Fidelity”, has done it again. The McIntosh
engineering staff has created a power amplifier without
compromise, using the most advanced McIntosh circuit
design concepts.
A continuous average power output rating of 300 watts
and with an output current of greater than 50 amperes per
channel, makes this not only the most advanced, but also
the most powerful amplifier McIntosh has ever manufac-
tured. The distortion limits for the MCC602TM are no
more than 0.005% at rated power output for all frequen-
cies from 20Hz to 20,000Hz. Typical performance at mid
frequencies is less than 0.002%. The true distortion read-
ings on the MCC602TM are so low, it takes special mea-
suring techniques to make accurate readings. The
MCC602TM 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
measuring 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 MCC602TM
involved several different techniques, all based on sound
scientific logic. Every stage of voltage or current amplifi-
cation 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
Technical Description
Inside the MCC602TM
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 11 on
page 18.
All transistors are selected to have nearly constant cur-
rent gain over the entire current range they must cover.
Output transistors in particular, have matched uniform cur-
rent gain, high current-bandwidth product and large active
region safe operating area. An automatic tracking bias sys-
tem completely eliminates any trace of crossover distor-
tion. All the resistors are Precision Metal Film types 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 MCC602TM 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 efficiency circuit design of the MCC602TM
contributes to low operating temperatures. McIntosh ampli-
fiers are constructed in an extruded aluminum tunnel that
has exhaust ports along its length. These exhaust ports are
tuned to provide even air flow, over the surface of the tun-