minates. A waveform comparator in the MC 2120 con-
stantly compares the amplifier input and output wave-
form. Waveform difference of the output wave is con-
verted to a voltage which is used as a control signal to
"turn off" the NORMAL indicator and to "turn on" the
LIMIT indicator. The LIMIT indicator turns on whenever the
waveform difference exceeds 0.5%. Generally, these
waveform differences are the result of applying voltages
at the input in excess of its rating. Because the limit in-
dicator circuit can show an overload condition as short as
one cycle of a 20,000 Hz signal a holding circuit keeps the
red indicator on long enough for the eye to see.
HEADPHONES
The output of the front panel HEADPHONE jack has been
designed to feed low impedance dynamic stereo head-
phones. Electrostatic headphones generally require higher
power than dynamic headphones. Connect them to the LEFT
and RIGHT OUTPUT contacts on the back of the MC 2120.
Plug dynamic headphones into the front panel HEADPHONE
jack. Adjust the front panel LEFT GAIN and RIGHT/MONO
GAIN control for comfortable headphone listening.
POWER
The power switch turns the MC 2120 ON or OFF. The
switch does not control the power outlet on the back panel.
If you wish to control the AC power from a preamplifier
control center leave the switch in the ON position. Be sure
the AC cord of the MC 2120 is plugged into the controlled
outlets on the rear of the preamplifier control center.
OFF: In the OFF position the AC power to the amplifier
is turned o f f .
9
www.freeservicemanuals.info
5/10/2017
Digitized in Heiloo Netherland
