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Appendix A
Connecting 100 V loudspeakers on lines with different voltages:
Connecting a 100 V loudspeaker on a 50 V amplifier output will not cause any problems;
this does however result in a loss of sound pressure level. The use of 100 V loudspeakers on
amplifier outputs with higher voltages (>100 V) needs to be avoided as this might damage
the loudspeaker. Below chart indicates the difference in sound pressure level (in dB) when a
loudspeaker is connected to different amplifier output levels:
Amplifier output:
50 V
70 V
100 V
Conversion table AWG to mm2:
AWG
24
22
21
mm2
0.25
0.34
038
Cable loss (stranded copper wire):
Cable resistance
R= ( *L)/A
R = resistance of single wire (in ohms)
= resistivity of material in ohms per meter, copper: 1.712*10
L = length of single wire in meters
A = cross section area of wire in m2
Cable loss (V) = I * (2*R)
I = current on wire
R = cable resistance (1 wire)
Example:
100 V/100 W loudspeaker connected at the end of 100 m/2.5 mm2 cable
R = (1.712*10
* 100)/(2.5*1
) > R = 0.6848 ohm
-8
-6
Cable loss (V) = (100 W/100 V) * (2 * 0.6848) = 1.3696 V
Cable loss (dB) = 20Log (Vout/Vin) = 20Log ((100-1.3696)/100) = -0.119 dB
Voltage rating of loudspeaker:
50 V
0 dB
n.a.
n.a.
20
18
17
16
14
0.5
0.75
1
1.5
2.5
Appendix A
70 V
100 V
-3 dB
-6 dB
0 dB
-3 dB
n.a.
0 dB
12
10
8
6
4
4.0
6.0
10.0
16
25
-8
2
1
35
50
15
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