User manual

2-12 P1200A User Manual
Signal
waveform
CF P
out
[W]
P
in
[W]
P
loss
[W]
Square wave 1 1900 2600 700
Sine wave 1.4 1200 1830 630
Pink noise,
compressed
music
3.5 200 500 300
Music with
medium
dynamic range
5 100 300 200
Speech, music
with wide
dynamic range
8 40 200 160
CF : Crest factor
P
out
: Maximum average output
power (sum of both channels)
P
in
: P1200A power input
P
loss
: P1200A power loss
P1200A Power balance
Average power consumption and loss of P1200A as a
factor of output power with pink noise signal
(load impedance 4 ohms, both channels driven, sum of
output power of both channels)
Average power consumption and loss of P1200A as a
factor of output power with sine wave signal
(load impedance 4 ohms, both channels driven, sum of
output power of both channels)
2000
1000
100
50
1 10 100 1000 2000
power [W]
average output power [W]
loss
consumption
2000
1000
100
50
1 10 100 1000 2000
power [W]
average output power [W]
loss
consumption
2.12. 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 music signal or speech signal -
the ratio of peak to sustainable RMS voltage of the signal.
The above table gives power figures for various types of signal
waveforms. The figures were measured on a P1200A driving 4
ohms loads (both channels) to the clipping point of both mainframe
power amplifiers.
Power input and thermal power loss as a function of average
output power for sine wave and pink noise signal waveforms can
also be derived from the two graphs shown below (Note that pink
noise signal reaches the clipping point of the amplifiers at approx.
200 W average output power).