Speaker Output in Watts- Convert RMS to PMPO

You might have wondered how a branded Sony stereo player which costs Rs. 20,000 offers only a sound output of 600 Watts, where as an unbranded player offers an output of 2000 W or 3000 W will be available for 1/10 of the price.

The problem is not with the dealer or the manufacturer, it is related to the unit in which the sound output is calculated.



There are two types of audio output grading system available. These are PMPO and RMS.

PMPO = Peak Music Power Output
RMS = Root Mean Square

Peak Music Power Output (PMPO) is a term popularised by advertisements. The term PMPO has never been defined in any standard but it is often taken to be the sum of some sort of peak power for each amplifier in a system. It is the maximum output a speaker can produce at a given time, and is only valid theoretically. Nowadays PMPO output is only used in cheaper systems and a way to fool customers because PMPO is always more in value than RMS.

An RMS power value is referred to as the real music power output of a speaker. It is a true indication of the output power of a given speaker across it's range of pickup frequencies. Nowadays branded music players such as Sony and Philips use RMS to denote the sound output of their speakers.

There is no proper formula to convert RMS to PMPO, but based on various observations it has been found out that 12W to 16W PMPO = 1W RMS

For the next time when you go to buy a new music system dont opt for a 3000 W PMPO to 300 W RMS one, because in theory a 300 W RMS speaker will offer you an output of more than 3600 W PMPO rating.