User manual

(4.0E) 2-11
Signal waveform Crest factor
Square wave 1
Sine wave 1.4
Pink noise,
compressed music
3.5
Music with medium
dynamic range
5
Speech, music with
wide dynamic range
8
Examples of Crest factors
5 10 100 200
30
100
400
consumption
loss
average output power [W]
5 10 100 200
30
100
400
consumption
loss
average output power [W]
Average power consumption and loss of E-PAC as a factor
of output power (W RMS into 16 ohms) with pink noise
signal
Power consumption and loss of E-PAC as a factor of output
power (W RMS into 16 ohms) with sine wave signal
340
204
78
43
--
484
318
131
67
--
239
150
59
32
132
114
82
33
--
288
232
149
55
--
153
141
113
40
1.0 1.4 2.4 3.5 1.0 1.4 2.4 3.5 1.0 1.4 2.4 3.5
0
100
200
300
400
500
600
700
800
Crestfactor
4 ohms (LO IMP)8 ohms
16 ohms
loss
output
Maximum output power and power loss of E-PAC for different signal
characteristics (Crest factors) at full level.
2.13. Power consumption and power loss
The power required from the mains supply and the waste heat
produced by the amplifiers power loss are variable figures
depending on the load impedance and the signal levels and
characteristics (e.g. speech, music).
In practice, the theoretical peak power consumption of a system
will only be sustained for a short period of time. Basing mains
current and air conditioning plant requirements on the peak
power consumption of the sound system would result in a
generously over-specified installation. The key factor in power
consumption calculations is the crest factor of the signal - the ratio
of peak to sustainable RMS voltage of the signal.
Power input and electrical (⇒ thermal) power loss for different
signal and load conditions can be derived from the graphs shown
below.