RMS and Peak definitions?

[Intercooler 10+ year member]

When trying to narrow down an amp selection which is more important? Say I have these speakers that are 100W RMS and 150W Peak. Which should I shoot for? Just as an example I have CDT's up front that the info say 165 Max or peak but everyone says they play best in the 200W range which goes past both.

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[SKyleS 10+ year member]

Most definalty RMS. Never go by Peak.

 

[Intercooler 10+ year member]

Just curious why and also would it hurt to go over like the example above?

 

[FoxPro5 5,000+ posts]

I typically overpower everything by about 150-200%. Search the term 'dynamic headroom' or go to www.bcae1.com and just start reading....and when you get tired read some more //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[squeak9798 5,000+ posts]

Just curious why

Because peak power is meaningless.

and also would it hurt to go over like the example above?

http://www.elitecaraudio.com/forums/showthread.php?threadid=124205 - Good read for you...specifically sr20dem0n's first response to the thread.

 

[johnson 10+ year member]

RMS:

Root mean square

Rms value of an AC sine wave is 0.707 times the peak value. This is the effective value of an AC sine wave. The rms value of a sine wave is the value of a DC voltage that would produce the same amount of heat in a heating element.

The RMS value of a function is often used in physics and electronics. For example, we may wish to calculate the power P dissipated by an electrical conductor of resistance R. It is easy to do the calculation when a constant current I flows through the conductor. It is simply,

But what if the current is a varying function I(t)? This is where the rms value comes in. It may be shown that the rms value of I(t) can be substituted for the constant current I in the above equation to give the mean power dissipation, thus:

In the common case of alternating current, when I(t) is a sinusoidal current, as is approximately true for mains power, the rms value is easy to calculate from equation (2) above. The result is:

where Ip is the peak amplitude.

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