Specifications

The meters have extremely fast rise time, about
500 microseconds for 90% accuracy. A tone burst of
500 microseconds is almost inaudible even at full
power.
The meters are protected from damage in the
event of overloading in the wrong meter range.
AUTOMATIC TEST SYSTEM
The Automatic Test System provides positive pro-
tection and extends the long trouble free life of an
amplifier. Each time the amplifier is turned on an
Automatic Test System measures and verifies ac-
curate performance at seven critical points in the
amplifier's circuits. The Automatic Test System
verification assures operational readiness before
operation starts and limits any damage should there
be component malfunction. Each time a test is
verified an LED number indicator shows which test
is being performed. An adjustable "beep" tone can
be heard with each test.
If in the testing an unacceptable voltage is en-
countered, the LED numeric designation locks to
isolate the faulty circuit. Faulty circuit identification
permits the service technician more efficient repair.
Without the Mclntosh Automatic Test System at-
tempts to locate a fault by the probing and testing
needed, will often create additional problems by put-
ting undue mechanical and electrical stress on the
circuit components. The Automatic Test System pro-
tects your investment.
THE MCINTOSH OUTPUT CIRCUIT DESIGN
To achieve long trouble free life in an amplifier it
is essential to have cool operation. Cool operation
results from the careful design of the output circuit,
matching of the output circuit to the loudspeakers
with an autotransformer and a mechanical design
that permits the use of generous sized heat sinks
providing adequate ventilation without the use of
fans.
The bipolar eptaxial output transistors and the
Mclntosh output circuit allows the amplifier to
operate as cool as possible. When there is limited
program demand on the amplifier only the optimum
number of output devices operate. When there is no
signal no output device is conducting. Conservative
Mclntosh engineering keeps operating temperatures
low assuring long life.
The interleaved multifilar wound Mclntosh design-
ed autotransformer transfers all the power you paid
for to all impedance taps. You are not power penaliz-
ed for operating at an output impedance of less than
8 ohms. The Mclntosh autotransformer does its out-
standing job without adding phase shift, limiting fre-
quency response or power output. The distortion
through the autoformer is 0.003% at 20 Hz and
unmeasurable at higher frequencies. In short, the
Mclntosh autotransformer is the ideal answer to a
difficult problem.
Heat sinks must be large and they must have ade-
quate ventilation for effective cooling. For example
the MC 2255 has 1100 square inches (7.64 square
feet) of radiating surface. In addition, the chassis
has been designed to permit the maximum amount
of air to flow over the heat sinks to conduct away the
life limiting heat.
Mclntosh amplifiers provide the correct connec-
tion impedance to drive numbers of speakers simul-
taneously. For instance the 1 ohm output will drive
eight 8 ohm speakers and deliver full power without
overheating.
MC 2155 shown in optional walnut veneer cabinet.
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