Page 19
Macro-Tech 5002VZ
Power Amplifier
Reference Manual
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.
40
30
20
15
10
9
8
7
6
5
4
3
2
1
2
5
10
20
50
100
.04
.06
.1
.2
.4
.6
1
2
4
6
10
20
40
8000
Ohms/1000 Feet
(305 Meters)
AWG (American
Wire Gauge)
Feet
Meters
5000
1000
500
100
50
10
5
1
.5
.1
.05
.01
#28
#26
#24
#22
#20
#18
#16
#14
#12
#10
#8
#6
#4
#2
#0
#00
#0000
R
L
Load
Resistance
(Ohms)
R
L
R
S
Damping
Factor
R
S
Source
Resistance
(Ohms)
Two
Conductor
Cable
Copper
Wire
Example Shown:
Load Resistance = 8 ohms
Desired Damping Factor = 500
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
1000 feet (305 meters).
1
0.5
200
500
1,000
2,000
20,000
5,000
10,000
.01
.001
.02
.004
.006
.002
.0004
.0006
.0002
0.3
1.5
0.6
3.1
6.1
15.3
30.5
61.0
152.5
305.0
610.0
1525
1
5
2
10
20
50
100
200
500
1000
2000
5000
.0002
0.6
0.7
0.8
1.5
0.9
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 damp-
ing factor can easily be negated by insufficient loud-
speaker 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.
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.
Fig. 3.12 Wire Size Nomograph
