Talk:Audio power

I deleted the term Class A in a paragraph with the example of the 100% efficient amplifier since a Class A amplifier can never be 100% efficient. I was temped to remove the 100% efficient term too since it really isn't needed for the example. —Preceding unsigned comment added by 69.253.87.22 (talk) 03:54, 4 May 2008 (UTC)

Pictures of advertised output powers on product boxes and the like.

I went to a dollar store, Kmart, and Target, intending to take pictures of misleading specifications, but found surprisingly few. I only found one system that listed "peak power", but it was merely twice the RMS power, which is arguably accurate (peak instantaneous power). I saw one other that listed RMS power as 20 W and "FTC power" as 12 W. Neither really warranted a picture, though. — Omegatron 02:21, 1 November 2007 (UTC)

Bad Science
No audio amplifier testing spcification used in the last 25 years specifies using a resistive load.

The inductive reactence of the speaker and the power factor are taken into consideration when testing.

Wikipedia should not declare time honored scientific measurements and standards to be of no value simply because you do not like how they are used in the audio equipment industry. Peak - Peak to Peak - Continous - average - momentary peak and many other power measurements have served science well for years.

RMS is Root Mean Squared and would not be equal to mean power with a sine wave. We must ask Root Mean Squared of what? Voice? Audio and Music all have different RMS values for the same amount of energy. RMS was created to match the thermal energy received by a resistor (Dummy Load) with an electrical measurement and reflects accurately the amount of signal power required to create that thermal energy. To make calorimeters and power meters coincide.

If you are trying to cook hot dogs with your 500 watt stereo these numbers are functional. The complex speech waveform and vastly complex music waveforms have very high peek to average ratios that make peek or impulse power formerly referred to as head room important to prevent clipping the peaks of signal when many frequencies come into phase momentarily durring a complex musical piece.

Digitally synthesized music is particularly bad at occasionally creating peaks that are up to 20 times the voltage of the average power. The peak capacity of an amplifier can be increased in many cases buy adding a larger capacitor to the power supply or lower internal resistance in the output stage semiconductors. Higher continuous RMS capacity requires increased continuous power supply capacity and output stage heat dissipation. A very high RMS Public address amplifier may perform poorly with digital music at a fraction of the loudness due to these differences.

While manufacturers may lie or publish false data and Music Power and PMPO ratings are not fully standardized the ratings are not usually meaningless. Speakers with better magnets and low resistance voice coils make more sound with the same electrical energy and may be factored into manufacturers rating in an attempt to give the shopper an idea of the comparable loudness one should expect.

i suggest removing all of the RMSes that are misnomers and using mean power. yeah it's a valid abbreviation, but it's still misleading. just mention it at the beginning and then use the real thing. - Omegatron 19:22, Dec 31, 2004 (UTC)


 * like it or lump it RMS is the term everyone in the buisness uses despite the fact it is a misnomer. Therefore i think it should stay. It is clearly stated at the begining of the article why the term is a misnomer and it is in quotes later on to try and reinforce this i think thats enough. Plugwash 19:37, 31 Dec 2004 (UTC)


 * Just because everyone's in the habit of doing something wrong doesn't mean we should encourage them. Besides, lots of manufacturers don't use it, because they know it's wrong.  I believe the normal wikipedia response would be to explain the incorrect usage and then use the proper term everywhere else.  Since the article is basically about "watts rms" i will change what i think should be changed and you can revert it if you want. - Omegatron 22:47, Dec 31, 2004 (UTC)


 * Eh, you're right. It's totally appropriate in this article because it's about marketing literature. - Omegatron 22:57, Dec 31, 2004 (UTC)


 * RMS is not a misnomer if you consider that (power)amps are normally rated for power output using a sine-wave at a nice middle-of-the-bandwidth frequency, in this case RMS means RMS, unless you want to nit pick over distortion and such caused by the amp itself. Secondly does anyone object to a section being added on peak-to-peak power (just a UK thing?) and PMPO being expanded to include peak music program/power output?--Pypex 23:01, 14 September 2005 (UTC)


 * No, that is simply mistaken, without any recourse to nit picking. If you were to actually measure the RMS power of an amplifier on a sinewave signal you would get a figure higher than the true power figure (the one you think you would get) which is actually the mean of the instantaneous power at all points over one cycle. Squaring the power is wrong, and gives more weight to the power at peak voltage than is correct. We square the voltage, to arrive at power, but that is a separate issue. A correct term, if you want to refer to RMS would be 'power based on RMS voltage measurement', but this is silly because there is no other valid way to measure power on an AC signal. The only correct term is 'mean sinewave power', since without a waveform specification you can chose any figure you want. I would object to any other method being described here, other than as in terms of explaining why it is not valid, unless it is backed by a standard. We have standards, notably an IEC one which specifies precise times for test duration and method. These should take priority over 'folklore'. Unless you can show me otherwise, I maintain that the term PMPO has nowhere ever been defined, and certainly not by a standards body. UK thing? As a professional audio measurement expert in the UK I can only say that the term PMPO is hated and despised by all fellow professionals. It's marketing speak, based only on a desire for high numbers by people trying to sell, should be exposed as such in any article on audio. --Lindosland 11:43, 21 March 2006 (UTC)


 * I do not like the statement that peak music power is usually twice the sinewave power. It confuses three issues - power supply sag, peak to mean ratio, and thermal limitation. Most power amplifiers will only give a little more true power short term, perhaps 10%, by virtue of having the full power supply voltage. Using peak power, which is twice the normal, is simply cheating on figures, and to be rejected. Thermal limitation is a complex business. Few modern amps are thermally limited in practice. Integrated amps chips have thermal protectin built in, but they are usually provided with sufficient heat sinking to prevent them cutting out (a sudden muting). Some high power amps do have thermal protection coupled with gain reduction. The common supposition that testing power amps at full output on sinewaves overstresses them is mistaken, since calculations show that maximum dissipation in the output devices of a class B amp occurs at about 60% of full output on sinewave drive, where the voltage across the devices is high. At 100% output the amp will run cooler, and at 100% flat out and clipping it will run cooler still (because the devices are almost switching, with no voltage across them for mush of the time). I believe there is actually a case for designing an amp with real music power capability, with say 10 times the steady sinewave power available on peaks, and sophisticated protection so that this was only available for handling brief music peaks (see Programme levels). Only with such a large ratio does 'peak music power' take on a useful meaning, but to my knowledge this has never been done. On modern compressed material it would have no advantage, but on properly recorded material it would be a revelation. --Lindosland 11:43, 21 March 2006 (UTC)

I think the external link, "An explanation of why RMS is a misnomer when applied to power" is not useful. The author of the article misidentifies the calculation for RMS: "...RMS (root mean square) power, would have to be defined as the square root of the time average of the square of the instantaneous power, since this is what 'RMS' means." RMS voltage is the square root of the time average of the square of the instantaneous voltage, and RMS power is the RMS voltage squared divided by the load resistance. The author is correct that the term "RMS power" is a bit of a misnomer and that the measurement he describes would be meaningless, but in doing so the article only confuses the point. Flagmichael (talk) 18:41, 10 February 2008 (UTC)

Incorrect equation at the end.
The last section claims that $$P_\mathrm{avg} = V_\mathrm{rms} \cdot I_\mathrm{rms} = \sqrt{\frac{1}{T}\int_{0}^{T} v^2(t)\, dt} \cdot \sqrt{\frac{1}{T}\int_{0}^{T} i^2(t)\, dt}$$

but it seems to me that it should be something like

$$P_\mathrm{avg} = \frac{1}{T}\int_{0}^{T} v(t)i(t)\, dt$$

Could someone show how this is derived? It looks like the magniture of a phasor, but that is only true of a sinusoidal system, not power in general. --njh 11:48, 16 May 2006 (UTC)


 * Well, the $$P_\mathrm{avg} = V_\mathrm{rms} \cdot I_\mathrm{rms}$$ is correct (for a resistive load only), and the square root integrals are the equations for RMS, so it looks correct. Your version agrees with Power_(physics) and, though.  Are these really just the same equation for the case of the resistive load? — Omegatron 14:27, 16 May 2006 (UTC)


 * I think that is correct, that purely resistive loads have ave power = rms voltage * rms current, but speakers are not very resistive (they have lots of inertia). --njh 02:45, 17 May 2006 (UTC)


 * I've updated it. — Omegatron 11:25, 18 May 2006 (UTC)

Example
"An amplifier labeled "500 W PMPO" but fitted with a 5-amp fuse can therefore deliver an average power of 5 A × 14.4 V × 60%, or about 43 watts."


 * Why are they assuming a 14.4 V supply? Is this a car amplifier?  Cars have 12 V supplies.  I don't know which type of amp this is assuming. — Omegatron 13:41, 17 May 2006 (UTC)


 * Car batteries are only nominally "12 volt". At rest, a healthy car battery is actually 12.6 volts.  While the engine is running, the alternator always maintains the cars electrical system at a higher voltage (in order to recharge the battery as necessary), ranging from about 13.5 to 15 volts.  14.4 volts is very common - much lower and the charging doesn't work very well, much higher and devices on board may be damaged. human 00:06, 29 March 2007 (UTC)

H-bridge
I don't understand NathanHurst's edit. An H-bridge seems to be a switching network for running DC motors. I assume he means a bridged amplifier, which is a very similar idea, but which I have never heard called an "H bridge". Also, if car amps are commonly bridged, then you could get 12 Vpeak out of them instead of 6 Vpeak, as the example in the article describes. Also, I don't know what any of this has to do with his removal of the fused plug example. — Omegatron 13:05, 18 May 2006 (UTC)


 * H-bridge is a topology to get full supply p-p voltage. most car amps provide this.  But the example was using 6v p-p and so was presumably not using h-bridge topology, instead a single class ab amp.  I just clarified this.  You could talk about a bridged amp, and then multiply everything by 2 or 4, but that would distract from the point.  I removed the remark about the fuse as it is simply a non-sequetar - a fuse blows based on average power, pmpo, whatever it means, is presumably a short duration thing.  Perhaps this particular model has a flywheel it charges up in quiet sections.  (Yes, obviously it doesn't, but it is not _proof_ that PMPO is wrong) --njh 22:33, 18 May 2006 (UTC)


 * (A bridged amplifier is, indeed, an "H-bridge". It looks like an H if you draw the loudspeaker horizontally between two facing push-pull output stages running off the same supply.) — Omegatron 04:40, 26 July 2007 (UTC)

To RMS or not to RMS, that is the question!
Dear engineer types,

I appreciate your discussion and follow most of it. But I believe this academic level is useful only to BSEE types (design engineers, most often) and not nearly as useful to we mere hands on technicians and especially the laity of the general public who might read this. For most just comparing the RMS power number is useful and real. The ins & outs of analyzing complex waveforms goes beyond the need for this article. Feel free to publish all you want in your engineering forums or in formal technical papers, but I request that we keep Wikipedia articles like this one user friendly for the common man. Don't get me wrong, your discussions certainly have their place, but blowing away people with the sophistication of your knowledge does not help them understand the basic question being asked.

(In other words, RMS power is plenty good enough in practice if you are not a design engineer)

sjb

137.164.224.92 23:35, 12 January 2007 (UTC)


 * We aren't going to dumb down our articles by removing the technical aspects. We should make technical articles accessible, though.
 * This article does seem to suffer from some overly-zealous conspiracy theory debunking bias, though, implying that the peak output power is a meaningless number. It's perfectly useful for comparing amplifiers with each other in a general way.  A guitar amp that outputs 10 W peak is obviously not as powerful as an amp that outputs 100 W peak.   Comparing two 100 W amplifiers would require more detailed specifications, but depending on the expected use, it might be a perfectly adequate number.
 * And totalling the power outputs of 5 channels of a surround sound amplifier is not completely misleading, either, since the audio power is all going to the listeners' ears. I'm not sure about the acoustic implications though.  How does the perceived sound intensity compare between a 2&times;50 W stereo loudspeaker system and a 5&times;20 W surround system?  How do the signals sum in the ear, assuming that they are highly correlated to each other?  Of course it depends on placement, too...
 * Since any normal audio signal is going to have a high peak-to-average ratio, expecting an amp to run at continuous sine wave power forever is unrealistic. To imply that an amp is of poor quality because it can't maintain its peak sine wave power infinitely is silly.  An amp playing music in normal use (or even heavily clipping) will never approach its peak sine wave power.  Amps are designed for normal music signals, and heatsinks and fans and such are tailored accordingly; to remove a realistic amount of heat per unit time.  It would be wasteful to overdesign the amp for conditions it would never see except on a test bench.  (And the amount of heat dissipated in the output transistors is not directly related to the output power anyway.  A full-scale square wave could easily generate less heat inside the amp than a normal music signal, depending on the topology and efficiency of the amp in different conditions.)
 * The article's trying to talk about a few different things at once, and not really getting them right. — Omegatron 04:59, 26 July 2007 (UTC)

_____

I agree with sjb.

I could care less about just about all the complicated engineering stuff. I think there are better resources online and offline to find out what RMS means than to look at Wikipedia. Just keep it simple. Why is RMS important when buying speakers? And what does it translate to when I plug the speaker in?

Is that so hard Omegatrom? —Preceding unsigned comment added by 146.232.75.208 (talk) 15:12, 21 May 2008 (UTC)

M. Shane —Preceding unsigned comment added by 146.232.75.208 (talk) 15:13, 21 May 2008 (UTC)

RMS is not a misnomer
It is my understanding that Audio Output Power (RMS) as opposed to Audio Output Power (PMPO) is an indication of the system used to calculate the power produced by a particular amplifier so that users can compare one amplifier with another. I believe that the RMS label simply indicates to the user that the amplifier is capable of generating a stated amount of power in a standard (resistive) load for a considerable amount of time with a continuous sine wave input. All measurements of the sine wave refer to its RMS value rather than any arbitrary instantaneous value.

Saying that Audio Output Power is measured in RMS is much the same as saying that the frame size of a bicycle is 21.5 inches (c-t) Any cycle mechanic would interpret this as a measurement from the centre of the bottom bracket to the top of the top tube. (c-t) doesn't actually state that directly, but by convention this is what it means.

Surely an article such as this should explain conventions used in measurement rather than nit pick at the semantics of the words taken at their face value? TDuckmanton 21:17, 19 May 2007 (UTC)


 * Yes it is. There is no such thing as RMS power, only power - and its unit is the watt. If measuring power delivered by sinusoidal V or A waveform we use RMS units as measurements of V and A for calculation. If measuring the power of a square wave we use the peak value of the waveform.


 * Try this article on the subject, IMO it does a better job than the Wiki one.


 * http://sound.whsites.net/power.htm


 * RichardJ Christie 10:33, 6 September 2007 (UTC)


 * Of course there's such a thing as "RMS power"; it's just the RMS value of the power over time. The reason this is a misnomer is because that's not the measurement that people are actually using or referring to.
 * The actual measurement is correctly referred to as "average power", and is derived from an RMS voltage, hence the confusion. There is such a thing as RMS power, but no one uses it. — Omegatron 15:36, 11 October 2007 (UTC)


 * That's a bit of a specious argument, as no one uses it because there is no point in calculating it. We could have RMS value for almost any variable whatsoever if you wish. In that sense you are perfectly correct. It exists as much as RMS values of stock market fluctuations exist. RichardJ Christie 08:34, 17 October 2007 (UTC)
 * As that article is no longer available you might try its archived copy: https://web.archive.org/web/20190101130959/http://sound.whsites.net/power.htm
 * Also, I've made my own observations on the topic: https://agcsystems.tv/rms-power-fallacy/  algocu (talk) 16:55, 3 January 2024 (UTC)

We could have RMS value for almost any variable whatsoever if you wish


 * Exactly. :-) — Omegatron 04:45, 25 October 2007 (UTC)


 * Yes, you could calculate the RMS value of any time-varying function. But that calculation is only meaningful if it has a practical use.  You could, for example, calculate the RMS value of your car's speed over a length of time -- but the number has no use to anyone.
 * Now, one can argue that, although "RMS power" has no physical or engineering significance, since it is used in the CE product industry, and if it is measured according to a strict standard, then it has utility.
 * But you may as well have conjured up some other fictitious quantity, like "polka-dot power," and used that.
 * In the end, since "RMS power" causes confusion, and is physically irrelevant, it was a mistake to develop such a standard, and it ought to be deprecated from further use. algocu (talk) 16:50, 3 January 2024 (UTC)

PMPO and shared resources
It is important to remember that a 5 channel sound system that shares one power supply will only have the designated peek impulse power on a given channel and only if that channel is the only channel experiencing the peek impulse waveform. This is usually but not always the case. If the same monaural signal is applied to all channels, each could not achieve the the rated peek at the same time and the system should be de-rated for such use.

Quit Making Lying Statements
Audio power is usualy not about speakers and is usually measured in db.

There is no technicaly regognized measurement called sine power. All sine wave measurements are for measuring sine waves - voice measurements are for measuring voice signals

Music program power measurements are for measuring the complex waveforms and content of music programming

- All major audio amplifiers use push pull circuitry the distortion percentages go down as power goes up until clipping is reached. - Distortion levels are never speced at maximum power output. - Measurement of harmonic and inter modulation distortion requires at least two frequencies to be present and can never be done with a single sine wave. - There is no manufacturer in the US today quoting maximum power capacity at high distortion levels or at clipping. Wikipedia should not make unsubstantiated allegations without references —Preceding unsigned comment added by 71.113.213.199 (talk • contribs)

dBs and sensitivity
I'm not sure what is meant in the section "Power and loudness in the real world" where it states a higher sensitivity speaker gives greater loudness. The way that it is worded suggests that with fixed power input, one can get infinite power output by making the speaker arbitrarily more sensitive. I though the dBs would be talking about signal to noise ratio, in which case a speaker rated at 84dBs would sound just as loud as a speaker rated at 90dBs, its just that a greater portion of the sound energy in the 84dB speaker would be distorted waveform. Or is it talking about efficiency of electrical to sound energy conversion, in which case the dB would be negative and the more efficient speaker would sound louder? What does "dB sensitivity" mean? It should be described better in the article to help people like me. —Preceding unsigned comment added by 203.94.186.226 (talk) 07:59, 28 September 2007 (UTC)

''The way that it is worded suggests that with fixed power input, one can get infinite power output by making the speaker arbitrarily more sensitive. ''
 * No. Think of it as the efficiency with which the speaker turns electrical power into sound power.  The speaker can only do as much work as you give it energy to do, but no speaker will ever actually do that well; much of the electrical energy is wasted as heat instead of turned into sound.  Sensitivity is used to compare the relative efficiencies. — Omegatron 15:42, 11 October 2007 (UTC)


 * Actually, efficiency is only somewhat related to "sensitivity", since sensitivity is measured at a single point in front of the cone, and directionality of the speaker plays into it as well. But they are closely related. — Omegatron 04:49, 25 October 2007 (UTC)


 * I tried to addres this issue with some elaboration on the definition of sensitivity, dB, measurement techniques, etc. and also elaborated on how physical properties of speaker systems relate to sensitivity without getting too mathematical. I was initially confused by what had been written. Unfortunately I did not have time to cite sources. The level of editing I did is far beyond what I normally do on Wikipedia. If I can I will add sources. I am fairly confident I did not make any glaring errors. This is a good article for people looking to understand what makes things loud and should be worked on more.208.127.245.193 (talk) 21:16, 26 August 2014 (UTC)


 * I see that you tried to tell the reader why decibels are used "to express perceived loudness", but decibels are also used to measure the more clinically calculated numbers such as actual acoustic power and actual electrical power. Since decibels can be used for both, your explanation does not work.
 * Otherwise, your explanation is long-winded but not wrong, as you attempt to tell the reader about the variables at play in loudspeaker performance and measurement. Binksternet (talk) 22:18, 26 August 2014 (UTC)


 * Relating speaker sensitivity to amplifier power requirements for a given perceived loudness in actual systems seems the original intent of the section. Some conflation of concepts is inevitable given the imperfect relationship between perceived loudness and dB let alone the complex interactions between sound waves and objects in space. If any editor knows of a way to clarify the distinction between dB in measurement realm and dB in perceived loudness without destroying the original intent of the section, be bold!CherylJosie (talk) 22:17, 1 September 2014 (UTC)

Speakers vs amps
One thing this article does poorly is differentiate between speaker and amp ratings. Both are given "RMS" and "PMPO" ratings, but the conditions are different. The peak power of an amps is directly limited by their voltage rails and the minimum impedance of the loudspeaker. It is impossible to have a higher peak instantaneous power than this (unless due to reactance?) But for loudspeakers, the peak instantaneous power is not as clearly defined, and has to do with destruction of the speaker. — Omegatron 04:48, 25 October 2007 (UTC)

can any on tell me on this
what do IHF termed watts mean? How are they different from Rms? which is more powerfull ? thnx —Preceding unsigned comment added by 77.35.34.91 (talk) 07:41, 7 March 2009 (UTC)

FTC Rules
The section on FTC rules seems incomplete. I know the FTC has been mucking around with the rule. Here's a link to some info, but it's not recent.

http://www.ftc.gov/opa/2000/12/amprule.shtm

75.71.201.190 (talk) 18:29, 21 May 2009 (UTC)

Perhaps we should have links to articles or a discussion on the IEC standards on the subject. I cant remember which standards are relavent at the momenet as it's 10 years since I worked in electroacoustice. I remember I was working in a product development Lab. We designed speakers and amplifiers. One of my jobs was to test prototype drivers.

For that company (a major european manufacturer) the "RMS" performance of a loudspeaker driver was assumed to be compliant with an IEC definition of measuring the RMS of drivers. this stated that the driver should be able to accept a "Programme music" test signal, which was band-limited pink noise, with a defined crest factor (possibly 2.4 - I'm not sure)

The driver would have to accept this signal at it's stated input power for 8 hours without suffering damage. - sure they got hot.

There were similar definitions for the RMS output power of amplifiers.

That laboratory was not involved in defining PMPO levels for the devices. that was defined by the marketing team, and there seemed to be no correlation to any of the factors used in the design. - but then few consumers feel that a 3 or 6 watt system sounds like a good buy.

I have encountered some devices (not normally on the consumer market except in very high end audiophile equipment) which does define the power handling in terms of its continuous power handling (RMS), with separate peak instantaneous levels, with stated duration of those events.

Ultimately what is needed is a proper standard to which the manufacturers can adhere. THis should state the continuous RMS - as this is clearly defined - and I would point out does not have to relate to a pure sine wave input (that's cheating, and not a true RMS value). plus a statement of the headroom in a clearly defined manner, with a statement of how long and frequent such transients should last.

Personally I use 4 100w RMS amps, plus a 150w RMS amp to power a pair of Bi-Amped speakers plus a seperate sub-woofer. As the speakers are probably around 90dB SPL @ 1m re 1W and I dont like the noise levle in the room to get too loud to hold a conversation (85 dBA) I'm probably using less than 0.25W per amplifier, leaving a 400% headroom to the stated RMS values of the amplifiers, and heaven only know ho much headroom vs the PMPO or similar (not quoted for these devices) Completely biased opinion: Dont bother buying anything which bothers to quote a PMPO or "Music Power" value. A device with 30W RMS or better per channel is likely to meet more than enough for a domestic situation, and professional equipment should have no reason not to quote proper, defined statistics. —Preceding unsigned comment added by Anruari (talk • contribs) 16:06, 8 June 2009 (UTC)

Dissapointing Editors
It is disappointing to see people who apparently are not well educated in the area of electronics/audio etc. making statements of 'fact' on this and other Wikipedia audio/ sound articles. It's almost frightening that people 'know' things and put it forward as the divine truth without basis/ references or any apparent technical knowledge. If you don't know about the subject it is perhaps best if you don't try to edit it. Even though uncited this article is technically one of the better ones IMHO.

RMS is about the only true measure of an amplifiers practical power. Peak power is almost irrelevant. What's the use of "power" if you have massive audio distortion? So called 'Peak Music Power Output' has no technical substance at all. It is, as noted by other editors, purely marketing hype.

RMS (as I understand it me) measures the area of a sine waveform which is proportional to the output power. I may be thinking more of RF here,(more my area) so for Audio, as I recall, 0dBm is 1 mW into 600 Ohms at 1kHz SINE wave. All other dBm measurement are based on that.

Other articles, such as Sound, Sound power, Sound pressure, Sound power level, and Loud music all have bits and pieces of the overall Sound picture, with much overlap. A lot of merging needs to be done (some are in train already). --220.101.28.25 (talk) 23:23, 19 December 2009 (UTC)


 * The definition of RMS is not the area of a sine wave and the definition of dBm does not rely on either 600 ohm, 1 kHz or sine waves. Please do not be uncivil to other editors, but by all means strive to improve the article.  Sp in ni  ng  Spark  00:52, 20 December 2009 (UTC)


 * I have only done testing under exactly the above conditions, but we working technicians need to recognize, I mean recognise, the reasons for encyclopedia articles such as this one being biased towards general and theoretical considerations and slighting the daily practices and purposes of particular countries or industries. No doubt as our newcomer learns to sign in and study our Wikitheories and practices, we'll be joined by an attentive and productive editor who won't disappoint us at all.  Jim.henderson (talk) 00:12, 22 December 2009 (UTC)
 * Yes, if you are testing audio telecommunications lines that's exactly what you will be doing, Jim, but test conditions are not at all the same thing as definitions. I started off measuring dBm of 13.3GHz into 50 ohms, but that's not the definition of dBm either. And yes, you are right, we should be nice to our new editors, we need the help.  Sp in ni  ng  Spark  01:36, 22 December 2009 (UTC)

←Sorry, ‘Spinny’ and company. I did not mean to come across like that. I had some particular entries above in mind ie. Quit Making Lying Statements. I have since also read a bit more of the previous posts and see RMS has been a bit a of a 'controversy'. Just like me to jump in without looking first. I had a my first ‘less than good’ experience on Wikipedia 10 days ago where an ‘innocent’ question started a right old verbal donnybrook at Talk:Animal_testing. As I said I’m more RF than audio, though I did learn this stuff many moons ago. I also found that RMS redirects back here, so it needs to be clearly defined.
 * Isn’t RMS an approximation of the average power? And PMPO is really meaningless? "the term PMPO is hated and despised by all fellow professionals" says User:Lindosland (who states they are "a professional audio measurement expert in the UK). I agree with User:Lindosland simply from the ridiculous claims I’ve seen on audio equipment boxes. If RMS is determined under specified conditions at least it should give a valid basis for comparision of different equipment as far as output power.(even if its not a direct measure of average output)
 * The article says “The term PMPO has never been defined in any standard”. Should be illegal to even have it mentioned in specs. I suppose though most countries have laws against misleading advertising, which I feel PMPO is.
 * I have been meaning to drop you a line after your comment I caught up with recently on the Printed circuit board talkpage. (track vs traces?) Then I had a look at the Glossary edit you “undid”. Absolutely the edit summary was misleading, so I followed it a bit more (too much time on my hands sometimes). I expected the company and the editor to be ‘obviously’ related (like [User:/Liammorriscirexx] and  http://www.cirexx.com were) but Geolocate said the editor was from India, and the company USA so apparently not related. Interesting.
 * I poked around a bit on related pages and found a dubious going on that I thought you might be interested in. On the FR-4 article it appears someone has ‘hijacked’ the page, I tagged it { {advert} } but it is almost { {spam} }. About 5 weeks ago (22/23 Nov.) one editor made massive changes, diff, the only editing they have done is this article and now ≈4 of the ≈5 URLs on the page appear to point to one company website. The 2nd para. is particluarly dubious.
 * ps. I'm not that new, I started on 9 September 09! --220.101.28.25 (talk) 19:40, 25 December 2009 (UTC)

Nice to see a (relative) newcomer learning our tricks with punctuation and maintenance tags and so forth. Understanding how to get along, to cooperate and elicit cooperation, can take a little more study. One useful tool for this is our Wikiautobiography or WP:USERPAGE where we can tell our fellows where we're coming from, geographically, educationally and otherwise. This helps others understand our WP:POV, a concept as useful for this purpose as it is dangerous in article text. Understanding breeds trust, which breeds smooth work. Anonymous editors can do good work with spelling errors, broken links and other non controversial repairs, but the resolution of controversies requires deeper trust. Sometimes a personal talk page is a big help.

Oh, and I think Root_mean_square provides a rigorous, if somewhat opaque, explanation of the relevance of that mathematical concept to power questions.

Animal testing? OMG I would never think of meddling in a perpetually red-hot page like that, no matter how well armored, umm armoured, with trust engendered by a long record of polite, precise and judicious editing. Jim.henderson (talk) 15:39, 27 December 2009 (UTC)

Jim.henderson (talk) 15:33, 27 December 2009 (UTC)

Two Criticisms, RMS and article reads like...
the article in many places doesn't read like an encyclopedia but like the editorial or buyer's gude advice section of an audio magazine. I know the inherent issues it's trying to address can only really end up sounding like that but it just doesn't feel appropriate in tone. If this is poorly explained by me let me know and I'll try to clarify it. Secondly I don't know what it's getting at with the dismissing of RMS as the stated terminology in industrywide published specs since, well since air was invented, but every spec by every reputable amplifier manufacturer states "watts RMS" into a specified load impedence and there is no ambiguity or voodoo about that as the article seems to imply, and above one of the editors links to the page on root mean square and it does not imply any ambiguation either. This seems to be the one constant in the equation over all these years and I'm not understanding what is less than absolute here. It's an article about an issue that certainly needs addressing for clarification but IMO only accomplishes more ambiguity! Batvette (talk) 09:42, 30 July 2010 (UTC)

Even though the term "RMS power" is commonly used by manufacturers to refer to average power (mostly to cater to customers used to seeing it called that), it is not correct from an engineering perspective, and this terminology is not used in any field other than audio. Nobody actually measures RMS power (since it would be physically meaningless); manufacturers actually measure average power into a resistive load. I think it is necessary to explain this, mostly for the sake of people who are engineers and who are confused by audio specification sheets. Psycoee (talk) 18:03, 7 August 2011 (UTC)

As a professional electrical engineer with an interest in hifi I absolutely endorse the comment made immediately above. I feel that, given the level of misunderstanding evident in this talk page it is worth trying to explain what the objection to the term "RMS power" actually is, and why, although it is commonly used by hifi advertisers, it is essentially meaningless to an engineer; I attempt to explain that below. The reason I came to this Wikki entry is that I saw a specification for an amplifier quoted as 120W RMS, and wanted to know what the manufacturer was trying to say to me. The main wikki entry explained that well - it means "average power" measured at a stated distortion level, and with a sinusoidal signal. In this respect I feel that article has served a useful purpose by explaining a commonly used, or vernacular term which has no clear meaning in a hi-fi context.

RMS voltage (Vrms) and RMS current (Irms)are ways of specifying a varying voltage and current such that the product Vrms*Irms is equal to average power developed in a resistor, the averaging period being one complete cycle of the variations of voltage and current. To calulate Vrms or Irms, a mathematical procedure or algorithm is used. In words this is as follows, assuming a time-varying voltage (V): (1) derive an expression for V^2, (2) square it, (3) find the average or mean value of the squared expression, (4) find the square root of the average. The relationship between the term 'root mean square' and this procedure should be clear. RMS values of I & V are useful since they can be used to calulate average power in a resistor (R) in an ac circuit in the same way as continuous power is calculated in a dc circuit, namely as Vrms^2/R, Irms^2*R, Vrms*Irms. If this is understood, it should be clear that the RMS-deriving procedure is not intended when people speak of "RMS power". So "RMS power", if it has a meaning at all, is quite different from the meanings of RMS voltage or RMS current. Mathematically, the RMS procedure outlined above could be applied to a cyclically varying power to give a true value of RMS power, but this quantity would not have any practical use, and is not what is meant when advertisers quote "RMS power" levels. What is meant is simply average power with a continuous sine-wave signal, and in my opinion it would be less confusing if that were stated. G4OEP


 * As a professional electronics engineer with an Audio Engineering minor and an interest in linguistics, I absolutely reject the comments made immediately above. Engineering terms are not tied to some arbitrary "true" translation based on a tendentious misunderstanding of English syntax. They exist to convey meaning. There are engineers who insist on their own special meaning for engineering terms, but for the last 70 years engineering educators have been trying to emphasize the importance of communication and teamwork, rejecting the idea of deriving a private engineering language. — Preceding unsigned comment added by 203.206.162.148 (talk) 10:37, 31 March 2020 (UTC)

Regional Variations
I have created a new section and moved region specific details, particularly those limited to the US, out of the main body of the article.109.155.177.114 (talk) 11:04, 11 August 2011 (UTC)

PMPO confusion
The article currently appears to confuse PMPO with peak power. In practice the definitions used behind manufacturer's PMPO ratings are, here in Europe, generally not based in the real world, and are marketing spin pure and simple. They are generally power figures that the amplifier is entirely incapable of delivering, either under real world loads, or more often under any load conditions at all. I daresay lots of people come here to understand an amplifier's pmpo ratings, only to go away very misinformed. Tabby (talk) 10:04, 16 July 2012 (UTC)


 * Indeed, the music power section appears to be written to justify the totally misleading claims of some manufacturers. Back in the 80s the joke was that at Amstrad "1W RMS = 10W peak = 1kW Music Power." 78.144.17.50 (talk) 14:14, 13 October 2015 (UTC)

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