what does P.M.P.O mean
 

ok ive baught a few sets of computer speakers for computers around the house
http://webspace.uber-mod-gods.net/johnwill/wspeak.jpg

i know what rms means

what does pmpo mean

i want to know if its just a marketing scam or what


example: i bought a 5.1 system the other day

5 speakers + sub it says 60 watts rms

and then it says 2500watts pmpo

it sounds like bs but i would like to know if any one has a clue

Well you could have used the search, or Google, but I'll tell you anyway.

PMPO = Peak Momentary Power Output

Ie the power that comes out of a speaker in an instant. Speakers only output that wattage for a fraction of a second, so the actual power is much less. RMS is a much better indication of the loudness of a speaker.

thanks i did do a google search all i got was websites selling speakers

PMPO is really a worthless measurement it can be manipulated to show just about anything heres and example

Teac PM-100 3D surround-sound speakers: 16W rms, 180W PMPO
Kinyo "200W" PC speakers: 3W rms, 200W PMPO

as you see the one with the lower rms has a higher PMPO, its just marketing rubbish id just pretend it wasnt there, you cant even compare like for like if you compare two PMPO figures on different speakers.

yeah its all a bunch of bs like i thought

Rule 1: Standards are only good as the measurement used to measure the standard.

Rule 2: Ratings are not equal.


PMPO (Peak Music Power Output) is a utterly useless power measurement, it is what the unit can deliver for an instant, manufactures do this to inflate unit wattage ratings to make an amplifier look more powerfull than they really are.

RMS (Root Mean Square), this is the most common power rating it is more usefull than PMPO as it is in general "continuous" half rated output.


Even with RMS rating you still you have to look at the surrounding information. I will show how Amplifier RMS ratings can be inflated and misleading:


For example a hifi unit could say "50 watts RMS output". First thing to look for is is that 50 WRMS for "one channel" or "both channels".

The realistic power rating for the unit could be "25 watts RMS per channel".



Then you have to think what frequency range was this measured at?

On a unit you could see "25 watts RMS per channel measured at 1khz".

If you look this is measured at only one frequency (not very music like) so realisticly the unit may well have a lot less power across the whole frequency range when playing.

A better rating could be "25 watts per channel measured at 20hz to 20 khz".



Then you think how much distortion was present in the test?

The unit could say "25 watts per channel measured 20hz to 20 khz at 10% Total harmonic distortion."

10% distortion is a lot, humans can usually detect above 1% Total harmonic distortion, so 10% THD is not very usefull.

The unit could say "25 watts per channel measured 20hz to 20 khz at 1% Total harmonic distortion."

While this is better but it is still on the threash hold of our hearing so a better rating would be "50 watts per channel measured 20hz to 20 khz at 0.1% Total harmonic distortion."

Do you see how ratings can be skewed by how weak the measurement is.

So so an Amplifier could be rated "25 watts RMS Per Channel Measured at 1 Khz, at 10 % Total Harmonic Distortion". Its real life output could be only a couple of watts per channel.

A much better rating would be "25 watts RMS Per Channel Measured at 20hz to 20 Khz, at 0.03% Total Harmonic Distortion".

I hope this breakdown is usefull.

what micb sed

OR

just look at the price, its a good quality indicater.
(just a joke... it does have some truth, but not always offcours).

but yeah, always look at RMS, and see if its a respectable brand, they (usally) won't scam you too much with what it says on the box.

when looking for a pair of quality speakers, go to a audio center, where u can listen to different pairs of speakers in a nice room with a good amp.

Power isn't everything by a long shot...
but thats basically what micb sed with all that technical thingy's, but I've never seen that on the box, lol :)

Don't forget impedance also. If there is an amp that puts out 180W RMS into 8 ohms but only 300 into 4 Ohms (instead of doubling to 360 like it should) there is some current limiting going on, so you aren't getting all the power you can from the speakers. I think this would be more common to sub-woofer amps.

For example Audiobahn has a 5000W rms amp, but that is at 1 ohm (not too uncommon for subwooofer arrays) and at 2 ohms it can put out 4000W. (Yes 5000W rms, it is rackmount and like 8-10U tall) granted if you need the extra wattage and are going to use it, you should be beaten to death for having that much in your car. (or should I say lowered SUV with spinners :rolleyes: and low profile tires)

basically PMPO = 6.02*10^23 X max RMS output. :D :hehe:

Thies thread is really about home Hifi and PC systems, but some of it applys to car audio.

What you say aound output impedence is partially correct but not always correct, it is very depended on the amp in question.

Some amplfiers are designed to supply there optimal power across its impedance range some are not.

Also you have to remember in a car charging system (Battery and Alternator) Input voltage drops as current demands increase.

Car amps are actully designed to operate at different voltages this can shew the ratings once again.

For example I know of some amps that can do 1200 WRMS but this is measured at 16 volts (very unconventional) so if you use the amp in an a standard car system then the amplifier will only see 13v-14.4v so the amp will only really output 700-800 WRMS, if your car voltage drops to 11v then the power will be even less.

That is why it is wise to look at both 12v and 14.4 volt power ratings on a amplifier.

Some of the current JL Audio range run a special regualted power system to that they can output there power between 1.5 and 4 ohm at any voltage between 11v and 14.4 volts.

Also don't forget sensitivity and distance measured :)

Talk about vuage statement that does not mean anything.

Sensitivity is a speaker measurement that is far from standard, there are many ways of measuring it and skewing it. In real life it can often mean very little indeed due to enclosure type, size defining efficiecny and frequnecy response. It does not even work at all in many appliciations expecially as it does not apply to frequnecies below 100 hz.

don't worrie this may be about computer speakers but i like this conversation so contenue