ebay TPA3116 2.1 amplifier

[Saturnus]

Thanks for your reply.
You are talking about the 'crest factor' of music right? I think I understand what you are saying here.
But, if I understand this correctly, when trying to amplify a pure sine wave with the PowerSoft amp, it would only do a fraction of the amplification of real music?

Taking this theory to the TPA3116, is the 40 w/ch measured in continuous watts or not? If not, then the power supply should be able to be a lot smaller than the rated output power of 80 watts, if I understand this completely...

Also, when I'm measuring class AB amps, most of them do reach their rated output using a pure sine wave on the input.
But using this method of measuring the output power, all amps (in particular class D) will never get beyond their power consumption VA rating ?

Yes. It's the crest factor.

The TPA3116 has 2*50Wrms with a 24V supply on 4 ohm speakers.

No, the power supply has to be able to deliver the peak output of the amp. Usually but not always a power supply rated at 100W can supply 200W peaks which is precisely what the TPA3116 will output. However, then you have not taken into account the power loss. A TPA3116 is about 90% efficient at peak output so the power supply has to be at least 10% larger to achieve full peak output. Or in other words minimum 110W.

Class AB and class D always measure the Wrms figure when connected to a sufficient power source. Taking the crest factor into account on power consumption does not change the fact that the amp still has to be designed as if it was to supply the full Wrms constantly. Apart from the cooling requirements naturally which can, and is, always designed with real use requirements in mind.

In the 18KW amp case. It is practically impossible to design a class AB amp that could deliver that as it would require around 13500VA power consumption with music signals. Or around 60A on 230V. Good luck supplying that.

 

[PsychoM]

Class AB and class D always measure the Wrms figure when connected to a sufficient power source. Taking the crest factor into account on power consumption does not change the fact that the amp still has to be designed as if it was to supply the full Wrms constantly. Apart from the cooling requirements naturally which can, and is, always designed with real use requirements in mind.

Okay, I think i get it now
Thank you very much for your kind explanation!