McIntosh MC 2500, Owner'S Manual

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Front Panel Information
METERS
Output power monitor meters indicate the output
power of each channel. Each meter has two primary
scales: WATTS and DECIBELS. When the METER
RANGE switch in one of the decibel (dB) positions,
peak signal readings are indicated on the lower DE-
CIBEL scale. When the METER RANGE switch in the
WATTS position, direct power in watts is read from
the upper WATTS scale. The meters are calibrated to
read average watts. The intermediate markings bet-
ween the calibrations represent, beginning with 500
watts, 200 watts, 100 watts, the indicated 50 watts,
20 watts, 10 watts, the indicated 5 watts, 2 watts, 1
watt, the indicated 0.5 watt, 0.2 watt, 0.1 watt, the in-
dicated 0.05 watt, 0.02 watt, 0.01 watt, the indicated
0.005 watt, 0.002 watt and 0.001 watt. Although the
meter calibrations are in average watts for a sine
wave signal, the meters electrically respond to sig-
nal peaks. The meters are voltage actuated and indi-
cate power accurately when the amplifier is oper-
ated into rated output load impedances.
The meters respond to the peak output of each
channel. Ordinary meters lack the capability of indi-
cating the short interval information in a sound
wave. The mass of the meter movement is too great
to respond to the nearly instantaneous changes in
music program material. Short interval information
can have a duration as short as half a thousandth of
a second. Ordinarily, a meter pointer moving over its
scale in such a short time would not be seen.
Mclntosh has developed circuits that drive the me-
ters to respond to the short interval information in a
sound wave to an accuracy of 90%. The electrical
pulse that drives the meter pointer is time stretched
long enough so that the peak position of the pointer
can register in the persistence of vision characteris-
tic of the retina of the human eye.
LEFT GAIN
The LEFT GAIN control adjusts the volume in the
left channel to the desired listening level. Turn the
control clockwise to increase the volume.
RIGHT/MONO GAIN
The RIGHT/MONO GAIN control adjusts the vol-
ume in the right channel to the desired listening lev-
el. Turn the control clockwise to increase the vol-
ume. When the output of the MC 2500 is connected
for monophonic operation and the rear panel MODE
SWITCH in the MONO position, the volume is con-
trolled by the RIGHT/MONO GAIN control only.
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