RMS and PMPO Defined

RMS:

RMS stands for Root Mean Square. It is a measure of the effective power produced by an amplifier. This is the maximum sustained power the amplifier can deliver to a load (speakers) at a specified impedance, and less than a specific distortion level (THD). It is calculated by the following definition:

The RMS (root-mean square) value of the function $f$ defined on $[a,b]$, whose square $f(x)^2$ is Riemann integrable on $[a,b]$ is defined to be

\begin{displaymath}RMS_{[a,b]} (f) = \sqrt{\frac{1}{b-a} \int_a^b f(x)^2 dx}.\end{displaymath}

The RMS value of any function is always taken to be positive.

PMPO

PMPO stands for Peak Music Power Output, and is normally a measure of the total maximum amount of power an amplifier can produce at any given distortion level (THD) during a short transient. This is a totally useless value for the understanding of an amplifier's power output capabilities, and is very often seen in lower quality mainstream audio products. It is used mainly as a marketing gimmick.

Back to top