15
than one loudspeak-
er connected in
parallel, the load to
the power amplifier
may drop to two
ohms or even less.
A power amplifier
connected to a load
that is lower than
optimum, causes
more output cur-
rent to flow, which
results in extra heat
being generated in
the power output
stage. This increase
in temperature will
result in a reduced
life expectancy for the amplifier.
The special Balanced Winding
Autoformer creates an ideal match
between the power amplifier output
stage and the loudspeaker. Refer to
figure 17.
There is absolutely no perfor-
mance limitation with an Autoform-
er. Its frequency response exceeds
that of the output circuit itself, and
extends well beyond the audible
range. Its distortion level is so low it
is virtually impossible to measure.
In the rare event of a power
amplifier output circuit failure, the
Technical Description
ThermalTrak
DC BIAS
OUTPUT
MUTE
THERMAL
SENSORS
BALANCED
AMP
POWER GUARD
ATTENUATOR
INPUT MODE
SWITCH
-
AMP
+
AMP
UNBALANCED
OUTPUT
UNBALANCED
INPUT
BALANCED
INPUT
BALANCED
OUTPUT
+
+
-
-
ThermalTrak
DC BIAS
Block Diagram
of the
Power Amplifier
(one channel shown)
Figure 14
Figure 17
Figure 16
expertise of McIntosh in the design and
manufacturing of autoformers is legend-
ary in the high fidelity industry.
The high efficiency circuit design of
the MC462 contributes to low operat-
ing temperatures. More than 2800
square inches of heat sink area keep the
MC462 operating safely with convec-
tion cooling. No fans are needed. Refer
to figure 16.
Autoformers
All solid state power amplifier output
circuits work best into what is called an
optimum load. This optimum load may
vary considerably from what a loud-
speaker requires. In the case of more
