16
nel cooling fins. Temperature sensors, attached to the inte-
rior of the tunnel, control the cooling fans. The fans are
normally off; if the program material contains sustained
loud passages demanding high power, the fans will turn on
to increase cooling.
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 loudspeaker requires.
In the case of more than one
loudspeaker 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 opti-
mum, causes more output
current to flow, which results
in extra heat being generated
in the power output stage.
This increase in temperature
will result in a reduced life
Block Diagram
of both
Amplifier Channels
Figure 11
Figure 12
expectancy for the amplifier.
The Autoformer creates an ideal match between the
power amplifier output stage and the loudspeaker. Refer to
figure 10. A McIntosh amplifier with an Autoformer can be
used to safely drive multiple speakers without reducing the
life expectancy of the power amplifier.
There is absolutely no performance limitation with an
Autoformer. Its frequency response exceeds that of the out-
put 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 fail-
ure, the McIntosh
Autoformer provides
absolute protection from
possible damage to your
valuable loudspeakers.
The unequaled expertise
of McIntosh in the de-
sign and manufacturing
of Autoformers is leg-
endary in the high fidel-
ity industry. McIntosh
Figure 10
www.freeservicemanuals.info
5/10/2017
Digitized in Heiloo Netherland
