Wire Size Nomograph - Crown Macro-Tech MA-5000VZ Reference Manual

Macro-Tech 5000VZ Power Amplifier
Use Good Connectors
1. To prevent possible short circuits, do not
expose the loudspeaker cable connectors.
2. Do not use connectors that might acciden-
tally tie two channels together when making
or breaking connections (for example, a stan-
dard three-wire stereo phone plug).
3. Connectors that can be plugged into AC
power receptacles should never be used.
4. Connectors with low current-carrying
capacity should not be used.
5. Connectors with any tendency to short
should never be used.
HOW TO DETERMINE
APPROPRIATE WIRE GAUGE
It is important to use loudspeaker cables with sufficient
gauge (thickness) for the length being used. The resis-
tance introduced by inadequate cables reduces both
the output power and the motion control of the loud-
speakers. The latter occurs because the damping fac-
tor decreases as the cable resistance increases. This
is very important because the amplifier's excellent
damping factor can easily be negated by insufficient
loudspeaker cables.
Use the nomograph in Figure 3.12 and the procedure
that follows to find the recommended wire gauge (AWG
or American Wire Gauge) for your system.
1. Note the load resistance of the loudspeakers con-
nected to each channel of the amplifier. Mark this value
on the Load Resistance line of the nomograph.
2. Select an acceptable damping factor and mark it on
the Damping Factor line. Your amplifier can provide
an excellent damping factor of 1,000 from 10 to 400 Hz
in Stereo mode with an 8-ohm load. In contrast, typical
damping factors are 50 or lower. Higher damping fac-
tors yield lower distortion and greater motion control
over the loudspeakers. A common damping factor for
commercial applications is between 50 and 100.
Higher damping factors may be desirable for live
sound, but long cable lengths often limit the highest
damping factor that can be achieved practically. (Un-
der these circumstances, Crown's IQ System is often
used so amplifiers can be easily monitored and con-
trolled when they are located very near the loudspeak-
ers.) In recording studios and home hi-fi, a damping
factor of 500 or more is very desirable.
3. Draw a line through the two points with a pencil, and
continue until it intersects the Source Resistance line.
Reference Manual
R
L
R
S
Damping
Factor
20,000
10,000
5,000
R
L
Load
Resistance
2,000
(Ohms)
1,000
40
500
30
200
100
20
50
20
15
10
5
10
9
2
8
1
7
6
5
4
3
Example Shown:
Load Resistance = 8 ohms
Desired Damping Factor = 500
2
Source Resistance = 0.016 ohms
Cable Length = 10 feet (3.1 meters)
Recommended Wire: #8 AWG or equivalent
wire with 1.75 ohms or less resistance per
1.5
1000 feet (305 meters).
1
0.9
0.8
0.7
0.6
0.5
Fig. 3.12 Wire Size Nomograph
4. On the 2-Cond. Cable line, mark the length of the
cable run.
5. Draw a pencil line from the mark on the Source Resis-
tance line through the mark on the 2-Cond. Cable line,
and on to intersect the Annealed Copper Wire line.
6. The required wire gauge for the selected wire length
and damping factor is the value on the Annealed Cop-
per Wire line. Note: Wire size increases as the AWG
gets smaller .
.0002 R
S
.0002
Source
Resistance
(Ohms)
.0004
.0006
.001
.002
.004
.006
.01
.02
Copper
Wire
8000
.04
5000
.06 Ohms/1000 Feet AWG (American
(305 Meters) Wire Gauge)
.1
1000
Two
Conductor
500
Cable
.2
1 0.3
2 0.6
#28
100
5 1.5
#26
.4
50 #24
10 3.1
.6
#22
20 6.1
#20
50 15.3
1 #18
100 30.5
10
#16
200 61.0
#14
5
500 152.5
#12
2
1000 305.0
#10
2000 610.0
#8
1
#6
4
5000 1525
#4
.5
Feet Meters
#2
6
#0
#00
10
.1
#0000
.05
20
.01
40
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