Specifications

production for which the loudspeakers have been
designed. If undersize wire is used, resistance is added
to the amplifier/loudspeaker combination which
adversely affects the performance. Added resistance
causes reduction of damping characteristics,
modification of frequency response and reduction in
power output.
Use lamp cord or wire with similar type of 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, No. 18 wire
or larger can be used. For distances over 30 feet
between the amplifier and speaker use larger diameter
wire. Select the correct size wire for the wire length
from the chart. It is recommended that the DC resis-
tance of the speaker leads be less than 5% of the
speaker impedance. Up to 10% can be tolerated. Resis-
tance of the leads should be computed for the length
of wire both to and from the speaker or speakers.
MAXIMUM WIRE LENGTH
- For 4 ohm Load -
Wire
Gauge Feet Meters
18
16
14
12
10
15
25
40
60
100
4.6
7.6
12.2
18.3
30.5
- For 8 ohm Load -
Wire
Gauge
Feet Meters
18
16
14
12
10
30
50
80
120
200
9.1
15.2
24.4
36.6
61.0
Wire lengths above represent the wire resistance
equal to 5% of the speaker impedance.
For multiple speaker operations, run separate leads
from the amplifier to the speakers.
CONNECTING LOUDSPEAKERS
Connect the leads from the left loudspeaker to the
Left and Common OUTPUT terminals on the MC7150.
Connect the leads from the right loudspeaker to the
Right and Common terminals. Use the terminal that
matches the rated impedance of your speakers 1, 4 or
8 ohms.
AC POWER
The amplifier AC power cord is plugged into a
120 volt 50/60Hz wall outlet, or into a outlet on the
preamplifier.
FUSE
A 7-amp slow blow fuse protects the MC7150
circuits. The fuse does not protect additional equipment
connected to the rear panel AC power outlet.
Front Panel Controls
ILLUMINATED OUTPUT WATTMETERS
The Mclntosh MC7150 is the first high fidelity
power amplifier to have Output Wattmeters that respond
95% full scale to a single cycle tone burst at 2kHz.
Voltage and current output are electronically measured,
multiplied and fed to a special circuit that accelerates
the pointer movement in the upward direction. When
the pointer reaches its peak it pauses only long enough
for the human eye to perceive its position, then drops.
It is almost 10 times faster than a professional VU
meter.
LEFT GAIN
Use the LEFT GAIN control to adjust the output
in the left channel to the desired listening level. Turn
the control clockwise to increase the output.
RIGHT GAIN
Use the RIGHT GAIN control to adjust the output
in the right channel to the desired listening level. Turn
the control clockwise to increase the output.
The input sensitivity of the MC7150 is 1.4V with
the gain controls full CW. If one desires to match the
2.5V rating for Mclntosh preamps simply turn each gain
control CCW to the detent position on the control.
METER MODE
The METER MODE switch has two positions:
WATTS and HOLD.
WATTS
In the WATTS position, the meter needle
indicates the variations in program loudness. Although
the primary output calibration of the meters is from 1.5
MC7150 Product Preview/Page 3
MClNTOSH LABORATORY INC., 2 CHAMBERS STREET, BlNGHAMTON, NEW YORK 13903