For all applications using 600 ohms use
Class I wiring if the installation must meet
the requirements of the National Electrical
Code.
LINE OUTPUT-MONOPHONIC
The octal socket marked LINE OUTPUT
has connections for operating the MC240
monophonically at 70.7 volts, 62 ohms or
300 ohms. For operating at 25 volts connec-
tions are made at the barrier strips.
To feed a 25 volt line, connect one side to
the screw marked COM on the LEFT barrier
strip. Connect the other side to the screw
marked 16 on the LEFT barrier strip. Then
connect with a wire the screw marked COM
on the LEFT barrier strip to the screw marked
COM on the RIGHT barrier strip. Connect,
with another wire, the screw marked 16 on
the LEFT barrier strip to the screw marked 16
on the RIGHT barrier strip.
The 62 ohm and the 70.7 volt connec-
tions are the same. To connect for 62 ohms
or 70.7 volts solder one of the leads to pin
#1 in the octal socket. The other lead is
soldered to pin #2. A wire is connected be-
tween pin #2 and pin #4.
To connect for 300 ohms one lead is
soldered to pin #2. The other lead is sol-
dered to pin #3. Connect pin #2 to pin #4
with a wire. With another wire connect pin
#3 to pin #5. Pin #1 is the center tap of the
300 ohm winding. The 300 ohm winding is
balanced to ground.
AC POWER
The MC240 operates on 105 volt to 130
volt, 50 to 60 cycle power. The amplifier will
be turned on and off if its power cord is
plugged in one of the auxiliary AC outlets on
the program source.
OPERATING THE MC240
Before turning the MC240 on check all
connections and plugs to see that they are
firmly and correctly connected. Check to
make sure that the tubes are firmly seated
in the proper sockets. After the following
adjustments have been completed the MC-
240 will operate without any further attention.
ADJUSTMENTS
LINE VOLTAGE
The LINE VOLTAGE switch should be set
to the position that more closely matches the
average line voltage in your area. The local
electric power company can usually tell you
the average line voltage in your area. If the
line voltage is between 105 volts and 120
volts put the LINE VOLTAGE switch in the 117
volt position. If the line voltage is between
120 volts and 130 volts put the switch in the
125 volt position. If the line voltage is un-
known, it is safer to operate with the switch
in the 125 volt position.
INPUT SWITCH
STEREO
With the input switch in the left position
marked STEREO the input of the MC240 is
connected to the two jacks marked STEREO
INPUT located below the BALANCE control.
The amplifier has an input sensitivity in this
position of 2.0 volts. This position has been
provided to be used with Mclntosh preampli-
fiers or any other high output preamplifiers.
The BALANCE control assists in balancing
the overall stereo system for equal loudness.
Equal loudness is affected by room acous-
tics, furniture placement, speakers and
many other things. With a monophonic signal
adjust this control until both loudspeakers
are equal in sound output.
TWIN AMP
With the input switch in the center posi-
tion marked TWIN AMP, the input of the
MC240 is connected to the two jacks marked
TWIN INPUT located below the two center
control knobs marked GAIN. The input sensi-
tivity in this position is 0.5 volt. This position
has been provided for use with a low output
stereo preamplifier, an electronic crossover
network, or as two completely separated
monophonic 40 watt amplifiers.
The two center control knobs marked
GAIN should be adjusted to match the input
sensitivity of the MC240 to the output voltage
of the program source equipment.
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