McIntosh MC 2500, Owner'S Manual

Page: 5 / 20

How to Connect
INPUT
Stereo operation:
Use shielded cables to connect the signal from
the preamplifier or any other signal source to the po-
wer amplifier. All connections are made on the back
panel of the MC 2500.
For stereo operation, the left output of the pre-
amplifier should be connected to the Left INPUT of
the power amplifier. The right output of the preamp-
lifier should be connected to the Right/MONO IN-
PUT of the power amplifier. The MODE SWITCH
must be placed in the STEREO position.
To minimize the possibility of hum the shielded
leads should be run parallel or loosely twisted toget-
her. Locate the cables away from AC power cords.
Monophonic operation:
A shielded cable from the signal source is con-
nected to the Right/MONO input of the MC 2500. The
MODE switch on the back panel of the amplifier
must be placed in one of the two MONO positions. In
these MONO positions the output of the right chan-
nel 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 ampli-
fied.
OUTPUT
Stereo operation:
To connect the left speaker first check the impe-
dance of the speaker which is usually identified on
the speaker itself or in the owner's manual. Connect
one lead from the common terminal of the speaker
to the LEFT OUTPUT terminal strip screw COMmon.
Connect the other terminal of the speaker to the
screw with the number corresponding to the speaker
impedance on the LEFT OUTPUT terminal strip. The
right channel speaker is connected in the same
manner on the RIGHT OUTPUT terminal strip. Figure
1 shows the connections for stereo operation.
STEREO LOAD
OHMS VOLTS
1 22.4
2 31.6
4 44.7
8 63.2
STEREO OPERATION
CONNECT LOW
SIDE OF LOADS
TO TERMINALS
LEFT
COM
COM
COM
COM
RIGHT
COM
COM
COM
COM
CONNECT HIGH
SIDE OF LOADS
TO TERMINALS
LEFT
1
W
2
W
4
W
8
W
RIGHT
1
W
2
W
4
W
8
W
When multiple speakers are to be connected to
either or both outputs, the combined load impe-
dance must be calculated and the load connected to
the appropriate impedance tap. The following Figure
2 will aid in selecting the correct impedance match.
Load
impedance
in ohms
0.9 to 1.8
1.8 to 3.6
Connect
to
1
W
2
W
Load
impedance
in ohms
3.6 to 7.2
7.2 to 14.4
Connect
to
4
W
8
W
Figure 1
Figure 2
If a load impedance is used that is lower than the
output impedance tap, then reduced power, increas-
ed heating, and possible distortion will result. If a
load impedance is used that is higher than the out-
put impedance tap, then the maximum available out-
put is limited.
Make all speaker connections at the amplifier on-
ly. For multiple speaker operation, parallel the leads
from the speakers to the amplifier.
Because of the high power available from the
MC 2500, be sure to use large diameter speaker
leads. In all cases, the leads to and from the speaker
should be twin conductor or twisted together.
Lamp cord or wire with similar type of insulation
can be used to connect the speakers to the ampli-
fier. For the normally short distances of under 20
feet between the amplifier and 8 ohm speakers #18
wire or larger can be used. For distances over 20 feet
between the amplifier and speaker use larger diame-
ter wire. Select the correct size wire for the wire
distance from the chart (Figure 5 page 4). It is recom-
mended that the DC resistance of the speaker leads
not be over 5% of the load impedance. Resistance of
the leads must include the length of wire both to and
from the speaker or speakers.
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