Rants - PMPO

Rants - PMPO

This is a new page, aimed at getting things which seriously piss me off, off my chest. We start the ball rolling today with something called PMPO

For many years, speaker and amplifier manufacturers have chosen to use one of two standard terms to express the power handling of their equipment. RMS (root mean squared) is the most accurate and honest way of expressing this. In simple terms a 100W RMS system means it will handle an average power level of 100W indefinitely. Simple isn't it.

Then we have "Music Power" output, a bit naughty really as it basically means you can mislead folks by simply doubling the RMS power you used to quote. All of a sudden that 150W RMS speaker cabinet in the corner is now magically rated at 300W mpo. Alas if you drive it hard from a 200W RMS amplifier you will kill the speaker. Not terribly helpful.

Now the difference between the two measurements above are bad enough - especially if you make the mistake of driving a 100W "music power" speaker from a 100W RMS amplifier. But things get worse. LOTS worse

PMPO (apparently stands for Peak Music Power Output) and used to be quoted as EIGHT time the true RMS value of the speaker. So now you can kill your 100W PMPO speaker with a 15W amplifier. Sounds grim? it gets worse.

Recently, PMPO multiplications have got to the point where it is just plain fraudulent. I have sitting in front of me, a 2000 Watt (Yep, 2 Kilowatt) speaker system, (PMPO of course) which a friend had managed to disintegrate. Any idea what the RMS power was (according to the speakers actually used inside the cabinet). Take a guess. take a WILD guess and then guess again.

36 Watts.

Hmm, lets see. 36 = 2000. We're pushing things a bit here don't you feel?

In short, these days most of the cheaper computer speakers you get are rated in PMPO, if you cannot see an RMS equivalent then I suggest you divide the figure given by about 50 and you will be somewhere close. A 200 Watt PMPO system, probably chucks out about 4 Watts RMS. It will be fine for your average bedroom or office - but one thing it isn't is 200 Watts.

A total and unmitigated con job. Manufacturers guilty of the gross misrepresentation are as follows, each and every one uses the Purely Mythical Power Output method of quoting speaker "power".

Genius (46 Watts RMS = 1500 Watts apparently)
Milford Sound
Trust (Bad name I think)  (7 watts RMS claimed as 1000 - a truly massive 142 times over rated!!!) You really could overdrive the "1 KW speaker" with a 10 Watt RMS Amplifier. They should be utterly ashamed of such outright dishonesty.

Honest guys are as follows - they rate as either RMS or music power (and often both to help you understand what you are REALLY getting as opposed to any hype)


If you know of any more shysters or good guys in the business, let me know and I'll update. Thanks.

The link below this line is just to help a friends site get spidered, nothing to do with PMPO :)