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convert PMPO to RMS

Discussion in 'General Electronics Chat' started by electroicarus, May 17, 2006.

  1. electroicarus

    electroicarus New Member

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    Hi ,someone know how convert watts PMPO to RMS?
     
  2. zevon8

    zevon8 New Member

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    You can't really convert the Peak Music Power Output (ahem) rating to RMS. PMPO is not much more than a marketing ploy, there is no real information contained in the number given, or how it was obtained.

    Think of it this way... those tiny little plastic computer speakers powered by batteries or a tiny wall adapter, with a rating of 300 PMPO. You would be lucky to get 300 Watts of heat from them if they were plugged into the wall directly, LOL.

    Audio is one of those worlds where unfortunately all sorts of hokey information is made up simply to look impressive on the packaging.
     
  3. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Quite right, PMPO bears no resemblance to a proper specification - I've seen PMPO values range from 10 times RMS to over 100 times RMS. Basically if anything is rated in PMPO it's just a load of rubbish, no honest manufacturer would quote using that!.
     
  4. dave

    Dave New Member

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  5. phalanx

    phalanx Member

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    As an example of how useless PMPO is, a buddy of mine has a set of computer speakers rated at 960 watts PMPO. His entire system takes up less space then the woofer in my speakers rated for 400 watts RMS. While not a high end amplifier by any stretch of the imagination, the amp I use is rated for 440 watts RMS into a 4 ohm load (2 channel) and it weighs a good 55 to 60 lbs. Most of that number comes from the massive transformers in it.

    If it is rated in PMPO, there is a good chance that it is junk.
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Mine is 400W + 400W RMS into 4 ohms, or 800W bridged into 8 ohms, and includes an eight channel mixer with two digital effects channels - it only weighs 12kg - because it's class D and uses a SMPS.

    BTW, I don't 'just happen to know' it's weight, I've just carried it downstairs ready to take to the gig Saturday (along with all the other gear), and I happened to notice the weight on the box.

    Not just a chance, only junk uses PMPO ratings.
     
  7. electroicarus

    electroicarus New Member

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    Thanks all ,therefore PMPO= JUNK,and is a invention of each manufacturer.
     
  8. Paul Obrien

    Paul Obrien Guest

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    divide PMPO by the number of speaker channels then divide the result by 2 and you might come close to the RMS output or you may not.
     
  9. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    That would only convert PEAK to RMS, PMPO would need dividing by a higher, unknown, number - different for every value!.
     
  10. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Music Power ratings are high because the measurement is for only a moment, before the power supply voltage drops due to being loaded. The frequency and amount of distortion aren't specified so could be anything.
    Peak power is simply double the real power.
    So Peak Music Power is meaningless.
     
  11. Thunderchild

    Thunderchild New Member

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    well my 240 watts pmpo turned out to be 3 watts each so 6 watts total but that was only the speackers I bet thear was no more than 1-2 watts per channel there judging but the ic and pathetic heatsink. then the transformer 9V 300 mA so you go figure. I think this pmpo thing only lasted a few years as now they are all back to rms but don't take their word for that either my 10 W woofer on my 2.1 system is really 8 wats and I darn't wonder what the speakers really are, but it is true that really 10 watts would be way too loud so many people just don't realize that 1 watts is sometimes ample unless you in a car and so ok I'll give you up to 5 watts per channel. All i see in higher power than necesary is better quality at a normal power level
     
  12. Dr.EM

    Dr.EM New Member

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    Yeah, PMPO seems to have dissapeared a bit, and manufacturers do quote RMS now quite frequently. However, that can vary quite greatly as some RMS measurements are taken at 1khz sine wave only and don't quote distortion.

    My new Hi-Fi amplifier is rated at 2x40W, the same as my old one, but it is significantly louder as it is measured across the full frequency spectrum and distortion at all levels is under 0.03%. 2x40W RMS from an amp like that is very loud (though loudness depends on the speakers, mine are quite sensitive), I wouldn't dare put it over half, doors start rattling and things well before that.
     
  13. Thunderchild

    Thunderchild New Member

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    yep well people got wise to publicity crap and it only worked when A was still using rms and B started quoting pmpo but then A started using pmpo as well so we were back to square one then booth A and B started telling it again in rms probably telling us what a joke pmpo is having used it though themselves its called pubblicity
     
  14. RadioRon

    RadioRon Well-Known Member

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    We still suffer the equivalent of PMPO mentality in power tools. Its surprising to see a small woodworking router or vacuum cleaner rated at 5 HP!
     
  15. audioguru

    audioguru Well-Known Member Most Helpful Member

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    They must measure the HP of those motors that have brushes when they are stalled and are beginning to smoke.
     
  16. RODALCO

    RODALCO Well-Known Member

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    Pmpo

    PMPO = JUNK

    is a correct statement, its' used by advertising agencies to promote so called hi powered audio equipment which is in fact substandard and only provides a fraction of the audio output value quoted.

    RMS is the correct value to be used and quoted over which frequency range.

    Used to be RMS at a steady 1 kHz frequency from my memory.

    As already said applies to powertools too, 1kW drill yeh??
    Looking at the motorsize, perhaps 400 Watt, they probably quote the power rating with motor armature in locked position, It may draw 1 kW, it will only last also a very short time prior to go up in smoke and sparks.

    Cheers Raymond
     
  17. Thunderchild

    Thunderchild New Member

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    my dad has a 701 W drill but that is a nice heafty bosh anybody try to tell me my little 420 W B&D is more than that and they lie sometimes I wounder whether it really is 420 but after comparing its performance to my dads I guess it is I just forget now and then I'm using mine not me dads lol
     
    Last edited: Jun 3, 2006
  18. ╧╧╧╧

    ╧╧╧╧ New Member

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    Actually, PMPO is not Junk!!!!!!!!!! it's like this:

    A speaker's power rating (in general) tells you how much A.C. power can be dissipated in the speaker's voice coil without damaging the speaker.

    Honest Power Ratings:
    The most honest way to rate a speaker is to give the rating as continuous RMS watts (ex: 150 watts continuous rms power). You may hear speakers advertised as "150 watt 6 x 9s" or "100 watt 6 x 9s" and you may instantly think that the "150 watt 6 x 9s" are better and will play louder than the speakers rated at 100 watts. The first thing you should realize is that speaker ratings are OFTEN exaggerated. Then you should ask if the rating is in RMS or peak watts and are the speaker ratings for instantaneous or continuous power. Most car audio speakers (with the exception of some subwoofers) are rated in peak power or music power. Only a few speakers (generally the higher quality speakers) are rated in RMS watts. While peak power is a legitimate way to rate speakers (as long as the manufacturer tells you that the power rating is in peak watts), it can be deceptive.

    Peak vs RMS:
    You know that peak power is 2*RMS power. If a speaker is actually capable of handling 150 watts of peak power it would only be rated to handle 75 watts RMS. If a speaker is rated to handle 150 watts 'music power', it may mean that the speaker will take only very short bursts of power approaching 150 watts RMS. Even if there are two speakers from different manufacturers which have the same power ratings, one of the manufacturers may be more conservative in their ratings than the other manufacturer. The more conservatively rated speaker would be more likely to handle its rated power. Bottom line, beware of power ratings on speakers. Knowing that some manufacturers are less than honest in their power ratings, will likely help you to make better decisions when buying speakers. :)
     
  19. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    How did that post contribute anything?, we all know what RMS and Peak are, and your post didn't even mention PMPO?.

    PMPO IS a completely junk rating, which you can't translate to any sensible rating, and no decent manufacturer ever uses it!.
     
  20. JimB

    JimB Super Moderator Most Helpful Member

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    What a lot of old tosh!

    Eventually you make the statement:

    Which seemed to be the general opinion of this thread anyway.

    JimB

    PS how should we pronounce your name? Spiky Thingy?
     
  21. phalanx

    phalanx Member

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    I would add that "music power" is another industry term designed to confuse people. I have no idea what it means.

    The combination of power handling and sensitivity give you a better picture of how loud a speaker can be. For any given input power, the more sensitive the speaker, the louder the output. A speaker with 3dB less sensitivity than another will require twice as much power to generate the same sound level.
     

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