amp and speaker compatibility

You know the answer to that question.

Sorry, I maintain that in the audio world, there is no such thing as "RMS power."  I quote from the Rane technical glossary: rms power No such thing. A misnomer, or application of a wrong name. There is no such thing as "rms power."  Average or apparent power is calculated using rms values but that does not equal "rms power;" it equals continuous sine wave power output into a resistive load.

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No - the R & L issue was something I considered after my last reply April28. My initial thoughts were both since both DC & AC cause e-mag force & displacement. A speaker is a device where IMO the imaginary (inductive) power does result in real (acoustic) power output unlike classical AC loads where the pf (power factor) has no impact on the real power consumed (ie, hence no extra energy required nor extra consumer electric-consumption charges). Hence speaker power should be a VAR (average power) relationship. Speaker heat will only be from the resistive component (ie, one of its inefficiency factors). As I wrote, I can't recall seeing the term continuous average power, though my main issue for amps etc has been NOT use vague or defined "peak" power etc as they have little relevance. From what you wrote, the apparent power is simply real RMS power divided by the cosine of the phase angle. The calculations otherwise will be the same - ie, involving the product of each frequency's voltage and current (ie, =0 if not the same frequency) across the frequency range. My concern would be that people would merely use the Vrms & Irms values for such calculations and use that as a CAP value. Maybe RMS specs have been used because "true RMS" meters are not uncommon (including power). I'm not sute about "true RMS Apparent Power" meters. But speakers will have an RMS power, it should simply be the VAR or "average power" times phase angle and (electrical) distortion factor (ie, pf = W/VA). My "RMS power" source is my ancient learnings and the heaps of relevant texts. The end result mainly falls under mathematics etc - eg, Laplace & Fourier transforms and their series expansions. As to what should be applied to speakers and amplifiers I can leave to authoritative references. I haven't investigated nor seen what has the better correlation (ie, RMP real or apparent power). And then which is used is a case of practicality. (If simple specs such as impedance or power at 1kHz etc is used, I can understand why RMS (real) power is used... if people can't handle full bandwidth specs...) At least we are in agreement about what RMS power is, whether real and apparent.

I checked Rane. It's not quite the RAND that I expected. I'd disregard their "definition" of RMS power since they fail to qualify what they mean. (And it certainly is not a definition.) And since they clearly refer to RMS power elsewhere (eg, in other definitions), it must exist. Someone should suggest they fix their RMS power definition else remove references to it in other definitions. They do not provide a definition for continuous power which I find strange. Maybe google's narrative accompanying Rane's ProAudio Reference is apt... "RaneNotes A series of technical notes written by Rane's technical staff. .... who claims to have posted the largest glossary of recording terms on the web. " I can interpret as a collection of terms or definitions - often linking to/from other sources (eg, Rane uses Wiki) - and hence not necessarily integrated nor consistent. F.ex, though Rane mention mains AC as a source of ground loops, this is not mentioned under their Ground Loop definition. Rane did however pass my first test. I usually check definitions of "power factor" (pf) to see if it is defined as the phase angle between current and voltage. It isn't - except for non-distorted waveforms (ie, sinusoid). (Otherwise SMPS etc that have very close to in-phase voltage & current would NOT have PFs of 0.6 and lower.) The def'n of PF is W/VA which they got right. (Or rather, they did not muck it up by adding "pf = cos-phi".) Other sources define continuous power as the product of RMS V & I (ie, VAR). But as some sources paraphrase, the reactive power is "power borrowed and returned" by the load to the power source. ERGO the load never used that power. ERGO the speaker can only use its REAL power. I love these contradictions that few else none seem able to explain.    I guess a speaker is a device that doesn't follow our understanding of the world. PS - some seem to infer that Continuous (Audio) Power is merely the long-term (or steady-state) RMS sustainable. AFAIAConcerned for equipment ratings, that is its "RMS" rating unless otherwise qualified (eg, 1kW for 1 hour). PPS - I incorrectly used VAR as the product of V & I (both real and reactive aka imaginary). That should be VA. It's P (Watts) + VAR that equals VA (ie, in a "power triangle"). Normally I'd back edit, but...

The fact remains: in audio engineering the term "RMS Power" is a misnomer and generally only used because customers want to hear it.  Continuous power is how legitimately rated amplifiers are rated, and is the proper term.Support the12volt.com

An FYI interim reply... From what I have seen, Continuous Power is merely "long term" RMS power. (Which - as I wrote - is what I expect RMS ratings to be. However I am only too aware of their undefined conditions when otherwise!) It is NOT related to reactive etc power which some seemed to suggest. There does seem to be quite some confusion on the subject. That IMO is probably not helped by ambiguous "definitions" like "Average or apparent power is calculated using rms values but that does not equal "rms power;" it equals continuous sine wave power output into a resistive load." (IOW, real power, the same as RMS power if RMS power is taken as the product of RMS voltage and current in a resistive load). In some cases, "continuous" seems to confer testing with other than a sinewave. Big deal - that is still RMS power. Even though Wiki have an incorrect definition of pf, they seem to agree with my other "RMS" stuff (ie, wiki: AC_power). I am still unsure what point is trying to be made re continuous vs RMS unless it's a case of how "RMS power" is tested or measured, but IMO that's another case of the under-knowledged complicating an otherwise clear topic or definition. But as I said, this is a mere interim reply. My curiosity has been rudely interrupted by other issues. If "RMS Power" is a misnomer when applied to amps or speakers, I would like to know why. (Assuming it isn't merely a "not short term" as opposed to a long-term RMS rating. That is easy to understand.)    Maybe you could shed some light, eg, recognised definitions or papers etc?

You don't know how to let go do you?  :)  Whatever, believe what you like.  It's Ok in this world to use the wrong treminology I suppose.  I just try to promote using the proper terms for engineering concepts n this forum.Support the12volt.com

Ha ha - nice try, But I totally agree. If I didn't, I certainly would not be writing here! So you can't offer any definition (Rane does not have one), nor any explanation, nor references?    I might have to resort to hardcopies! To me it seems like people think that by measuring continuous power they are somehow measuring the "actual" power. Not so. Hence I'm trying to find out WHY they want Vrms x Irms instead of the real power used. I can understand why amp designers use it, but not system users. Can you at least say how it is measured? Or is it simply the mathematical product of the V & I RMS values (which as they say, is NOT RMS power - the real power of any source or load). And please forgive me for expecting explanations of the type I try to provide on this forum. I paraphrase etc rather than mere vague quotes from questionable sources else add I think or I don't know, and maybe the occasional "too difficult to explain". I'll report back what I find, though it will probably become another of those some day curiosities.

Ah - d'oh - I think I get it. To quote from your linked Rane definition. "... the rms value of the voltage by the rms value of the current... It's the amount of power the casual observer thinks is available (hence, apparent), but because of power factor may not be -- the real power is usually less. " Sorry, I thought you were inferring that what I said was wrong. I was taking you to be far more than a "casual" observer. Meanwhile I was perplexed by what was wrong. And sorry about the "nice try", but all too often I find litols and pushers that resort to the same tactic. As the gurus say, that's a good sign... I still have 3 definitions for continuous average power of which Rane's Vrms x Irms is one. And whilst no one has said CAP equals "real" (aka RMS) power, I have yet to see where and how "they" apply CAP measurements. Not that 3 different definitions helps! I see it as people's confusion with "specs". I often hear how "specs are crap" because they don't provide the full picture. Of course not - people don't want to see equivalence circuits or transfer functions. They merely want a few standardised metrics so that they can easily compare different equipment. When those metrics aren't suitable (eg, 1kHz for subs), new measurement parameters are defined. I have seen reasonably complete specs whether transfer functions from inputs (at various mV) to output (at various Watts), or graphical or tabulated data. And even though I was capable at the time (of the simpler transfer function method), it was not easy to transfer those to a meaningful value or expression, especially for different loads - eg, speaker impedances and conditions. AFAIK, the only "simple" method is to use simple circuit equivalences in the s-domain. The it's the simple application of Ohm's Law etc and converting back to "real" time domain expressions or frequency & dB graphs etc. But that's probably not for people that prefer to uses "resistance" instead of "impedance" for speakers etc. So if you have some nice link to the practical application of CAPs for audio design, I'd be most interested. Until then, I'm happy to stick with real power as heat as the simplest "standard" one-line method on which to base performance limits. From there it gets more complex, but that involves program content (which is one of the CAP definitions I've seen) and from there almost borderless complexity. To me Rane's misnomer statement is like stating how the "solar system model" of atoms is totally inadequate, as is the electron or ion model of electricity. (We "know" electricity exists, yet it still cannot be assigned a single unit as can other base entities... LOL!) Not that that effects the level of work we do nor it's validity - provided we stay within the model (eg, the guy that argued "but a half (AC or audio) cycle is like DC..." No it isn't - DC content does not hold for sub-cycles).    In summary: I am asking WHY is CAP the appropriate measure for speakers etc as far as YOU are concerned?   What does it specify that real power does not? If YOU can answer that, I can move on.

I measure amplifier output power with a tone generator, an oscilloscope and an 8-ohm resister bank.  Or by using an Audio Precision 2722 in the lab.  How do you do it?Support the12volt.com

IOW, the CAP = apparent power = "real power" where I have been using "RMS power" as "real power" (since it it calculated similar to RMS as opposed to direct multiplication of RMS values of voltage and current). And since you are using a resistive bank and NOT speakers, there is no reactive power hence "apparent power" = "real power". Or is it a wire-wound or coiled resistive bank that has inductance etc? In that case, what is its inductance?