Talk:Audio power

message: 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)

message: 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)
replies: text: 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)#Average_electrical_power_for_AC and , though.  Are these really just the same equation for the case of the resistive load? — Omegatron 14:27, 16 May 2006 (UTC)
replies: text: 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)
replies: text:  I've updated it. — Omegatron 11:25, 18 May 2006 (UTC)
thread_title:  Incorrect equation at the end. 

message: "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)
replies: text:  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)
thread_title:  Example 

message: 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)
replies: text: 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)

text: (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)
thread_title:  H-bridge 

message: 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)
thread_title:  Speakers vs amps 

message: 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)
thread_title:  can any on tell me on this 

message: 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)
thread_title:  FTC Rules 

message: 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)
replies: text: 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. SpinningSpark 00:52, 20 December 2009 (UTC)
replies: text: 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)
replies: text: 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. SpinningSpark 01:36, 22 December 2009 (UTC)

text: * ps. I'm not that new, I started on 9 September 09! --220.101.28.25 (talk) 19:40, 25 December 2009 (UTC)
thread_title:  Dissapointing Editors 

message: 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)
replies: text: 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)
thread_title:  Two Criticisms, RMS and article reads like... 

message: 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)
thread_title: Regional Variations

message: 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)
replies: text: 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)
thread_title:  PMPO confusion 

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