Amplifier Efficiency
04-12-2005, 10:09 PM
#31
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What in the heck are you guys going on about?
RMS - Root Mean Square - the square of a waveform is taken, the function is averaged over time and the square root is taken, OR, I use a true RMS meter, or the RMS voltage function on my scope - they tend to be close.
For a resistive network (which I am currently using), RMS AC level is equivalent to a DC in terms of the work done Watts.
It might be me, my lack of sleep or the fact that I don't know what you guys are going on about, but where did I say anything about taking an 'average' in my discussion?
Here is some good reading on making power measurements: http://cp.literature.agilent.com/lit...988-6916EN.pdf
Since the waveforms I am measuring have very little clipping, the crest factor remains and high and the measurements remain accurate.
Haunz:
You are correct, The average level of a sine wave is 0.636 of the peak value. What do you use that for in terms of a power calculation? We are measuring Watts, the amount of work done in a circuit. The formula is (Vrms x Vrms) / Rl, as you know.
I work enough hours each week (usually 50-55) that there is of course potential for me to make a mistake. None of the 113 different car audio manufacturers whose products I have reviewed have any problems with my test methology, given the parameters that I have set out for the tests. They may not like the way I do them, but they don't dissagree with the results.
If you have a question or concern about my test methods - just ask, don't waste your time, or mine trying to undermine my efforts or discredit what I do how I do it.
I take that as a great insult.
RMS - Root Mean Square - the square of a waveform is taken, the function is averaged over time and the square root is taken, OR, I use a true RMS meter, or the RMS voltage function on my scope - they tend to be close.
For a resistive network (which I am currently using), RMS AC level is equivalent to a DC in terms of the work done Watts.
It might be me, my lack of sleep or the fact that I don't know what you guys are going on about, but where did I say anything about taking an 'average' in my discussion?
Here is some good reading on making power measurements: http://cp.literature.agilent.com/lit...988-6916EN.pdf
Since the waveforms I am measuring have very little clipping, the crest factor remains and high and the measurements remain accurate.
Haunz:
You are correct, The average level of a sine wave is 0.636 of the peak value. What do you use that for in terms of a power calculation? We are measuring Watts, the amount of work done in a circuit. The formula is (Vrms x Vrms) / Rl, as you know.
I work enough hours each week (usually 50-55) that there is of course potential for me to make a mistake. None of the 113 different car audio manufacturers whose products I have reviewed have any problems with my test methology, given the parameters that I have set out for the tests. They may not like the way I do them, but they don't dissagree with the results.
If you have a question or concern about my test methods - just ask, don't waste your time, or mine trying to undermine my efforts or discredit what I do how I do it.
I take that as a great insult.
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