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Bosch Security Systems | 2011-02
Praesideo 3.5 | Installation and User Instructions | 4 | Amplifiers en | 181
a Distortion < 1%, 1 kHz, nominal mains power or
battery >53V, max. 1 minute (acc. to IEC 60268-3).
b Distortion < 1%, 1 kHz, mains power or battery
>50V, max. 1 minute, ambient temperature 55 °C
(acc. to EN54-16).
c Distortion < 1%, 1 kHz, battery 48V, max. 1 minute,
ambient temperature 55 °C.
d Alarm tone level, distortion < 0.3%, 1 kHz, mains or
battery (>43.5V), max. 30 minutes, ambient
temperature 55 °C.
e Distortion < 0.3%, 1 kHz, mains or battery >43.5V,
continuous, ambient temperature 30 °C.
f Distortion < 0.3%, 1 kHz, mains or battery >43.5V,
continuous, ambient temperature 55 °C.
10.7.11 Derating
The graph shows the continuous power used for
emergency tones, speech, etc. as function of the ambient
temperature.
If the amplifier is loaded with loudspeakers up to its
rated output power (see section 10.7.10), you can still
play music and speech for an indefinite long period of
time at an ambient temperature of 55 °C, because of the
crest factor (or peak-to-average ratio) of the audio
signals. The crest factor of music and speech is typically
6 to 8 dB, which makes the required continuous power
25% or less of the rated output power. Alarm tones are
set to -3 dB maximum by Praesideo, resulting in a
required continuous power of 50% of the rated output
power. This can be delivered for at least 30 minutes at
55 °C ambient or continuously at 30 °C ambient.
Frequency response:
PRS-1B500, PRS-2B250, PRS-4B125
60 Hz to 19 kHz (-3 dB) at -10 dB with maximum
capacitive load and rated load resistance
PRS-8B060
80 Hz to 19 kHz (-3 dB) at -10 dB with maximum
capacitive load and rated load resistance
Power bandwidth:
60 Hz - 19 kHz (-3 dB, distortion < 1%) at 50% of the
rated output power
Signal/Noise ratio:
> 85 dBA with pilot tone off
Amplifier output limiting:
Soft clipping
Acoustical noise level:
< NR35 at 1 m, fans at half speed
< NR40 at 1 m, fans at full speed
figure 10.19: Maximum switching power
55
25 30 35 40 45 50 55 60
50
45
40
35
30
25
20
Continuous Output Power
(% of Rated Output Power)
T (°C)