peak/ rms

[gary_1.2Merit]

if i kno the peak power out, ie 50watt how do i work out the RMS power out? i kno it means root mean squared but dnt kno how to wrk it out

[music junky]

Speakers are tested to a point where they start to distort, say a speaker has had 50 watts through it and it distorts at 60 ? then they recommend 50 watts rms any more ? then distortion.

[Nick]

Peak = RMS x √2

√2 is the square root of 2 .

So, to work out RMS simply reverse the equation

RMS = Peak / √2



Funnily enough, if you look on a speaker, you'l see 50w input power and 300w peak power. you put these numbers through the equation and they do not come out as expected !

The definition of RMS and Peak are as follows.

When you have a sound wave, it's in a sine wave form. Basically it's a wiggly wave. inbetween 0v and lets say 20v. , it's Peak voltage is 20. The RMS is simply the average of voltage throughout the whole of the sine wave, Most people would think that it would be 10v ! - Logical i suppose, seeing as it's the average of 0-20v (0+20/2 = 10v) . But your forgetting that the wave is curved and not a striaght binary format. So this is why you need to use the root2 calculation as it basically takes into account the curvedness of the sine wave.

to be honest i don't know why the speakers say 50w RMS input, but yet they say 300w peak power

[Adam]

Yeah thats right, RMS is just the average through the peak positive and negative wave.

[Nick]

i thort bout this one now

I was giving you the equation for the peak voltage, and if u use that on the stated RMS and peak power that is written on your speakers they don't work out.

This is because as you increase the voltage you also increase the current which increases the power P = IV (i think) in a non-linear way. That's why the peak power is a lot larger then rmsxroot 2, because it exponentially grows within the equation