Take a look at this site:
http://www.signaltransfer.freeuk.com/powerout.htm
If Vcc is taken to simply be the rail voltage your formula may be bit optimistic. Rload is the usual nominal 8 ohms. the calculation in the above web site also takes saturation loses and the Re resistor into account, which seems to me to be a bit more correct
In any case, that formula represents the power just before clipping. It's ok as a nominal standard that everyone understands, but it seems to me that something better could be devised since even just before clipping commences, distortion has usually started to increase pretty dramatically. For most any amp, if you plot distortion vs. power, it will rise only gradually until shortly before max power is reached and then it shoots up dramatically. I would like to see a standard calculation that specifies some way to rate the power at a point before the dramatic rise in distortion starts. I think that would be somewhat more useful for making comparrisons - - but what do I know?
http://www.signaltransfer.freeuk.com/powerout.htm
If Vcc is taken to simply be the rail voltage your formula may be bit optimistic. Rload is the usual nominal 8 ohms. the calculation in the above web site also takes saturation loses and the Re resistor into account, which seems to me to be a bit more correct
In any case, that formula represents the power just before clipping. It's ok as a nominal standard that everyone understands, but it seems to me that something better could be devised since even just before clipping commences, distortion has usually started to increase pretty dramatically. For most any amp, if you plot distortion vs. power, it will rise only gradually until shortly before max power is reached and then it shoots up dramatically. I would like to see a standard calculation that specifies some way to rate the power at a point before the dramatic rise in distortion starts. I think that would be somewhat more useful for making comparrisons - - but what do I know?
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