How to Connect
INPUT
STEREO OPERATION
Use shielded cables to connect the signal from
the preamplifier or signal source to the power
amplifier. To minimize the possibilty of hum the
shielded cables should be run parallel to each other
or loosely twisted together. Locate the cables away
from speaker leads and AC power cords. All connec-
tions are made on the back panel of the MC 2155.
For stereo operation, the left output of the
preamplifier should be plugged into the Left input
jack of the power amplifier. The right output of the
preamplifier should be plugged into the Right
(Mono) input jack of the power amplifier.
In stereo operation the MODE SWITCH must be in
the STEREO position.
MONOPHONIC OR SINGLE CHANNEL OPERATION
A shielded cable from the signal source is plug-
ged into the Right (Mono) input jack of the MC 2155
only. The MODE SWITCH on the back panel of the
amplifier must be placed in one of the MONO posi-
tions. In the MONO positions the output of the right
channel input amplifier is fed to both left and right
power amplifiers. The Left INPUT is disconnected.
Only the signal fed into the Right (MONO) input will
be amplified.
Be certain that the MC 2155 is never operated in
the stereo mode with the outputs connected for
monophonic operation. Should the MODE SWITCH
be left in the STEREO position and the outputs re-
main strapped for a mono parallel load, one channel
will attempt to drive the other which causes high cir-
culating currents and overheating.
OUTPUT
Be certain the loudspeakers connected to the MC
2155 are capable of handling the power output of the
amplifier.
Selection of the proper gauge wire to connect the
loudspeakers preserves the quality of sound repro-
duction for which the loudspeakers have been de-
signed. If undersize wire is used, resistance is added
to the amplifier/loudspeaker combination which
adversely affects the performance. Added resis-
tance causes depreciation of damping characteris-
tics, modification of frequency response and reduc-
tion in power output.
Use lamp cord or wire with similar insulation to
connect the speakers to the amplifier. In all cases,
the leads to and from the speaker should be twin
conductor or twisted together. When using 8 ohm
speakers and for the normally short distances of
under 30 feet between the amplifier and speaker, #
18 wire or larger can be used. For distances over 30
feet use larger diameter wire. Select the correct size
wire from the chart below. It is recommended that
the DC resistance of the speaker leads be less than
5% of the speaker impedance. Resistance of the
leads should be computed for the length of wire both
to and from the speaker or speakers.
For multiple speaker operation, run separate
leads from the amplifier to the speakers.
Wire
Gauge
18
16
14
12
10
MAXIMUM WIRE LENGTHS
For 4 Ohm Load
Feet
15
25
40
60
100
Meters
4.57
7.62
12.19
18.29
30.48
For 8 Ohm Load
Feet
30
50
80
120
200
Meters
9.14
15.24
24.38
36.58
60.96
Wire lengths above represent the wire resistance
equal to 5% of the speaker impedance.
STEREO OPERATION
Check the impedance of the speaker which is
usually identified on the speaker itself or in the
owner's manual. Connect a lead from the common
terminal of the left speaker to the amplifier LEFT
OUTPUT terminal strip COMmon screw. Connect
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