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faq What are the differences between Program Power, Peak Power, Peak Program Power, AES Power, IEC Power and RMS Power
What are the differences between Program Power, Peak Power, Peak Program Power, AES Power, IEC Power and RMS Power ?
Only IEC and AES Power handling capacity are standardized values.
* IEC Power: the IEC 268-5 Standard (IEC for International Electrotechnical Committee) Second Edition 1989-07 defines the Power Handling Capacity of a loudspeaker as the square of the RMS voltage of the ''weighted simulated programme signal'' that the loudspeaker is able to withstand continuously during 100 hours, divided by its rated impedance value. The manufacturer must specify the load enclosure and/or the cross over characteristics with the results
* AES Power: The AES2-1984 Standard (AES for Audio Engineering Society) is the most frequently used Standard in Professional Audio and Sound Reinforcement. It is defined as the square of the RMS voltage of a ''defined band-passed pink noise signal'' that the loudspeaker is able to withstand continuously during at least 2 hours, divided by the impedance value at Zmin. While a free-air test is specified in the standard, many manufacturers, like PHL AUDIO, run this test in a load enclosure and specify its characteristics with the results, for more realistic values
The other power types are more fanciful:
* RMS Power: The statement of RMS power proceeds from an obvious concern for accuracy but is not standardized. It is usually defined in practice with sinwave signals and may relate to the maximum thermal power that the device can withstand. But neither the frequencies nor the test duration which are of great influence on the results are stated
* Program Power: Program Power is often stated in the data sheets while not standardized. It is usually defined in practice as twice (+3dB) the powerhandling capacity and generally corresponds to the power amplifier matching value requirement for music programmes
* Peak Program Power: This program is also used but it is not standardized. It allows to publish very advantageous power values, because it corresponds to the instantaneous peak value which is defined as almost twice (+ 3dB) the program power value !
An example based on our 15" SP5050 is quite revealing of the differences between each designation:
* Power handling capacity according to IEC 268-5 : 350W
* Power handling capacity according to AES 2-1984 : 500 W
* RMS Power : 500 W
* Program Power : 1000 W
* Peak Program Power : 2000 W
http://bcspeakers.com/page.php?id=54
How does B&C calculate their power ratings?
- B&C Speakers specified Nominal Power Handling is measured according to AES2-1984 standard. The transducer under test is driven for a two hour period with pink noise signal, having a crest factor of 2 (i.e. 6 dB) and filtered to the working range of the transducer itself (for instance, a 50-500 Hz range is typical for woofer testing). Cone loudspeakers with ferrite magnets are tested in free air, while neodymium magnet speakers are mounted in a box whose characteristics (volume and tuning) are described in their technical specifications. Compression drivers are coupled to their recommended horn. Power is calculated using the RMS value of applied voltage – averaged over the test period – and the minimum value of electrical impedance within the working range of the loudspeaker. After the test, the transducer must be in working order, without permanent impact on its technical performance. Due to the transient character of most musical programs, whose crest factor is commonly above 8 - 10 dB, it is customary to specify a “Continuous Program Power Handling”, double the Nominal Power Handling, as a recommended amplifier power in order to fully exploit the thermal and mechanical capabilities of the transducer without any clipping in the amplifier stage. On the contrary, when the amplifier is pushed to its limits and shows frequent saturation, its power specification should be less than the rated Nominal Power Handling of the loudspeaker.
alltid nåt.
Dom flesta konversationer är i själva verket monologer som framförs i närvaro av ett eller flera vittnen.
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/ din rasp i röven
av PerStromgren » 2010-01-13 15:06 
