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Thread ID: 32335	2003-04-15 22:43:00	whats PMPO wattage in PC speakers...?	forrest44 (754)	Press F1

Post ID	Timestamp	Content	User
136076	2003-04-15 22:43:00	Hi. I have a 4.1 sub/sat amplified speaker system for my PC. When I bought the speakers (it was setup as 2.1) they we listed as 650W PMPO on the box. What does PMPO mean, compared to RMS?	forrest44 (754)
136077	2003-04-15 22:57:00	forrest44, Multiply the RMS rating by the last three digits of the manufacturers phone number to get PMPO. The term is there to sell speakers using BIG numbers and is almost entirely useless. Professional sound gear is still rated using RMS, which loosely means the avourage continuious power a speaker can handle well. BTW efficiancy is where it's at. If it takes 30watts to get the X noise out of a 30watt speaker, does that make it better than a 3watt speaker that needs just 3watts to acheive the same? I think not, but watch people race to get the BIG 30 watt speaker! .Clueless	Clueless (181)
136078	2003-04-15 23:32:00	>> What does PMPO mean, compared to RMS? Peak Maximum Power Output and Root Mean Squared while RMS is a far better indication, it can still be twisted by its variables, the most known of which being THD (total harmonic distortion). so check out the thd ratings because 30w @ .1% thd is a lot better than 30w @ 10% thd. and here's a quick copy/paste from a google search: Question: I was wondering what the formula was to be able to convert from PMPO to RMS or vice versa. Any help would be greatly appreciated Response: The RMS power is the only power rating you really need to be concerned about. If you are looking at an amplifier''s specs, look for the dynamic headroom figure. It should be in dB. If the dynamic headroom is 3dB then the maximum output power of the amplifier is twice the RMS power. So if the RMS power is 200 watts at 8 ohms the maximum power (PMPO) will be 400 watts at 8 ohms. Lots of amps do not have a dynamic headroom of 3dB, and in fact a lower dynamic headroom is generally better meaning that the amp has a stronger power supply and can put out higher RMS power, which is what is important. PMPO comes only in short bursts while RMS power can be sustained. hope this can be of some help	whetu (237)
136079	2003-04-16 00:29:00	basicly put PMPO is just anouther salesman bullshit spec . you can make it mean anything you like . i remember when PMPO first started . 2 identical speakers would have same RMS but different PMPO depending on what manafacture they where bundled with . anything with a PMPO rating is going to be crap so ignore it ;-)	tweak'e (174)
136080	2003-04-16 01:49:00	A good guide is the power input to the amplifier . I have seen some with powerbricks which make it clear . A 12V 250 mA (3W) supply isn't going to provide 130W of sound output . All "power" ratings in the HiFi (and computer, home theatre, etc) should be taken "with a pinch of salt" . Or a bit more, then discarded . Lies, Lies, Lies .	Graham L (2)
136081	2003-04-16 02:09:00	Hi Clueless: Correct, efficiency of speakers is the thing, but your suggestion about watts & X noise seems confusing . To me, anyway . Maybe you can explain . It seems unlikely, as you imply, that one could get the 'same X noise' from any speakers driven at 3watts & 30watts . I would suggest that for speakers of the same efficiency one would get the same X noise, at the same RMS input . I imagine the confusion arises because of what the wattage rating of speakers means, compared with other loads such as, say a light bulb . I understood that the wattage rating of a speaker means that it is the maximum wattage that the speaker will handle, without distortion . I doubt that it means the speaker will load the amplifier with that wattage rating . But for say a 100watt light bulb, it will load the power supply with 100watts . In my experience, I've found that a larger high efficiency speaker produces excellent results even from say a modest 3 watts RMS amplifier, compared with using a smaller 3watt speaker that you mentioned . Any comments . .	Bazza (407)
136082	2003-04-16 04:09:00	Sorry i was unclear . . . . >It seems unlikely, as you imply, that one could get the 'same X noise' from any speakers driven at 3watts & 30watts . From the same speaker obviously one would get more noize from more power . However there are speakers and speakers, there are some that will require one tenth of the power to make the same amount of noize as others, particually with tweeters . My own 4x300Watt 15"JBLs in "W" bins are great for really shaking the walls of large halls . This is because they are EFFICIANT . Later model equivelant speakers are rated at 600watts, oddly the cones have the same size and the potentual to move the same distance . What does that tell you about the new rating????? . Clueless	Clueless (181)
136083	2003-04-16 04:19:00	I believe they measure the PMPO as how loud it can go unsustained, regardless of distortion. Which I guess would mean they could produce 650W of horrible noise for a very short burst of time.	bmason (508)
136084	2003-04-16 06:57:00	Hello again Clueless: Thanks for your reply . It is appreciated, and you are quite correct about the tweeters . Less power is needed at the high frequencies, and so tweeters are smaller & dont need to 'move air' like your 15" JBL's do for lower frequencies that 'shake the walls' . I'm impressed with your setup of 4 x 300watt JBL's, and can imagine the fabulous sound you can provide . As far as the question about 300 v 600 watt speakers with similar cones & cone travel, maybe the 600watt ones have firmer dampening on the cone spider & cone surround to enable them to tolerate the higher power, without distortion . Cheers .	Bazza (407)
136085	2003-04-16 10:19:00	Hi Bazza, >>As far as the question about 300 v 600 watt speakers with similar cones & cone travel, maybe the 600watt ones have firmer dampening on the cone spider & cone surround to enable them to tolerate the higher power, without distortion. Actually there is very little difference between the E140 and the modern equivelant the 2226. The full cone kits are interchangible. The major difference is a different magnet structure. They are supposedly 1 db more efficiant but i beleive the new higher power rating is simply that once they were rated conservativly, (Sound great at 300W within tougher specs) and now they are rated for better sales (will handle 600W OK) Most JBL series have had similar magical increases in power handling without alot of design change. Other brands even more so. PMPO (to get on topic again) shows an extention of this trend to simply give things the big rating that people want to hear. .Clueless	Clueless (181)
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