Talk:Audio system measurements

message: I'd rather this article was not merged with Audio quality measurements as I started the latter, and it's associated series, after looking at this one an deciding that it was beyond hope! I say that because it muddles ideas of system measurements with quality measurement and goes on to say that measurements do not measure quality!
While I agree that listening is always important, I and many others regard audio quality measurement to be about exactly that.  If it doesn't work, then that's because you are making measurements that were not designed to measure audio quality as subjectively perceived. I believe that professionals in the UK and Europe had this sorted out decades ago, with the development of weighting curves based on subjective experiments, but that the US has yet to realise this.  I'm quite happy to discuss things, and to work to improve this article, but until I have time to do that I'd appreciate it if the intentions of the one I started (to give a proper UK/European professional understanding of the term) were understood and preserved there. I know that many of the things said in this article are commonly stated ideas, but since they are easily shown to be wrong, they would be better stated perhaps on a page entitled 'common audio misconceptions' (with explanations as to why they are so), which I have considered starting --Lindosland 00:59, 21 March 2006 (UTC)
replies: text: Sounds like a POV fork. — Omegatron 02:39, 21 March 2006 (UTC)

text: This article is not about quality measurements, and doesn't claim to be in any way. It's purely about quantitative measurements that are usually made and quoted in specifications. At least that was the original intention - perhaps some other editors have confused the issue since the initial text was drafted, in which case a cull is probably in order. However, since this is not about quality measurement, I don't think a merge makes sense anyway. Graham 04:42, 21 March 2006 (UTC)

text: I've now merged the only substantial content in this article into Audio system measurements.  I'm going to go through and clean it up some more, and then I'll delete this article.  If you're like to help, please feel free to edit.  152.3.41.65 (talk) 01:06, 28 June 2012 (UTC)

text: Merge completed. Source article now redirects here. --Kvng (talk) 02:39, 2 July 2012 (UTC)
thread_title:  Merge 

message: As an example I will take this, which at first site is a correction of a commonly abused measurement. Yes, PMPO is nonsense, never defined anywhere, and number one hated term to be erased from a million advertisements (which seem to take power and multiply by a factor chosen at whim). RMS power though is also wrong, since without a definition of the test waveform and the averaging period (root MEAN square) it has no single meaning. Power in a steady state system is indeed calculated as rms, but its the VOLTAGE that is squared, averaged, and rooted, not the power! There have been many articles pointing out this simple error, and also pointing out that if you actually take a 1w (sinewave power) amplifier and calculate the RMS of the power over the cycle, the answer is not 1w but something a bit bigger! The correct term (almost never used) is 'max sinewave power'. Driven with a squarewave, a 1w amplifier will give 2w (of actual 'true' power!) out, which serves to make the point that its the waveform that we must specify, by convention, and nothing to do with rms, or even 'true' power. --Lindosland 01:10, 21 March 2006 (UTC)
thread_title:  RMS Power is WRONG!

message: I thought it a good idea to write a new intro which makes clear the real distinction between subjectively valid quality measurements and basic measurements. Also a section explaining why they differ. Hope this meets with approval. I would still suggest keeping the other set of articles as they do go into much more detail that would be appropriate here. Note that there is an article on A-weighting plus a set on Equal loudness contours which I did a lot of work on, to balance the other one on ITU-R 468, and that all give a history together with benefits and weaknesses. This seems quite fair to me, and allows users to follow the whole story through in detail if they wish to. --Lindosland 17:56, 5 April 2006 (UTC)
thread_title:  New Introduction etc 

message: A recent edit by User:Howard Doctor replaced "Reducing cone excursion" with "Reducing a driver's bandwidth" as a method for reducing Intermod distortion (IMD). I hold that both are valid methods. I'm reworking the paragraph to include them both. Binksternet (talk) 15:39, 1 October 2008 (UTC)
thread_title:  Cone excursion 

message: ===Frequency response===
I made some changes to the section on frequency response. The first thing I did was to write a short description of what the frequency response measurement means. The next thing I did was to remove some stuff about what happens if the frequency response is not flat. Below I've highlighted the text I felt needed changing:
The signal should be passed at least over the audible range (usually quoted as 20 Hz to 20 kHz) with no significant peaks or dips. The human ear can discern differences in level of about 3 dB in some frequency ranges, so peaks and troughs must be less than this. Much modern equipment is capable of less than ±1 dB variation over the entire audible frequency range. Rapid variations over a small frequency range (ripple), or very steep rolloffs are considered undesirable as they can correspond to resonances associated with energy storage which produce delayed echoes and hence colouration, or decreased quality, of the sound.
Research by Toole  has shown that changes in frequency response much smaller than 3 dB may be audible. His work focused on unwanted resonances in loudspeakers. He showed that a resonance with a quality factor = 1 and amplitude of 0.3 dB may audible on some signals. His work has also shown that resonances with a high Q (i.e., a resonance with a small bandwidth and relatively large amplitude) are often less audible than resonances with a low Q (i.e., a resonance with a large bandwidth and relatively low amplitude) [2 refs]. The revision above seems to imply the opposite, that rapid variations in frequency response (high Q) are less desirable (more audible) than smaller variations in frequency response (low Q).
I decided not to summarise Toole's work in the article. I thought that it was too specialised in this context.
===Unquantifiable?===
I've made some revisions to this section. What I've tried to do is improve the article by rewriting the section and adding references.
I've added references to articles in Audio Critic and Stereophile magazine. Audio Critic and Stereophile represent two different viewpoints on the usefulness of objective audio measurements. I've also referred to the work of Dr Floyd Toole. His work is relevant because he has linked objective measurements to the results of listening tests. Dr Toole used double-blind tests in his research. To try and maintain NPV, I've mentioned that there are other people who prefer to use non-blind listening tests (Stereophile magazine). Enescot (talk) 22:45, 4 May 2009 (UTC)
thread_title:  Changes to section on 'Frequency response' and 'Unquantifiable?' 

message: I've made some revisions to this section. What I've tried to do is improve the article by rewriting the section and adding references.
I've added references to articles in Audio Critic and Stereophile magazine. Audio Critic and Stereophile represent two different viewpoints on the usefulness of objective audio measurements. I've also referred to the work of Dr Floyd Toole. His work is relevant because he has linked objective measurements to the results of listening tests. Dr Toole used double-blind tests in his research. To try and maintain NPV, I've mentioned that there are other people who prefer to use non-blind listening tests (Stereophile magazine). Enescot (talk) 22:45, 4 May 2009 (UTC)
thread_title: Unquantifiable?

message: The question of what should go here and what elsewhere interests me. I don't think the coverage of the subject is quite right yet here, so may I suggest it aims to:
* list all the technical terms one may find in specifications for audio equipment, even "PMPO" (even though it is hard to pin such terms down, and we generally don't like them)
* distinguish between (and warn about) some terms, e.g. the frequency range of a speaker may be quoted as 50Hz to 18kHz, yet the frequency response might be 110Hz to 11kHz plus or minus 10dB; distortion might be quoted as "about 1% at normal listening levels" (yep, I've seen it!) yet 10% at full rated power; some mention should be made of the value of graphs of parameters (e.g. to show cross-over distortion is significant at low volume levels, even though the distortion is only 0.02% at 20W (and then only at 1kHz into a purely resistive dummy load)
* mention terms like "unconditionally stable" and some places that define them (note that different manufacturers will use teh terms differently; it is worth having several links and a range of definitions sometimes).
* give examples for ratings, including what is common for "average" equipment, what is very good, and links to some research as to what is detectable by the human ear.  There should be separate pages for what distortion is audible, what distortion is "pleasing", what input impedances are "standard", f-m curves/weighting systems for noise, and so on.
* There is virtually nothing on how the measurements are made. There should be (at least) mention of some of the standard IMD tests, DIN standards, measurement microphones and anechoic rooms; ideally some links to articles on testing each major amplifier and speaker characteristic.
* There should be at least a paragraph on relating the buzzwords of typical hifi magazine reviews (like "warmth", "spatial perspective", "speed") to technical, objective measurements (a bit of a difficult job, but somebody has to do it!).  The gooblygook is relevant to the topic, even if it may be "unscientific".
* I'm not sure whether this is the place to include CMRR and other characteristics of small subsections (e.g. opamps), but rather how this affects the overall system (although I'd be happy to see a table of characteristics of components mentioned, alongside the "externally noticeable" effect they have). Maitchy (talk) 21:47, 3 February 2010 (UTC)
replies: text: Any of the above discussions can be brought to this article if there are verifiable, reliable sources to support them. Bring it on! Binksternet (talk) 22:49, 3 February 2010 (UTC)
thread_title:  What "Audio system measurements" should and should not have? 

message: Damping is only a factor as long as the signal is in phase with the electromotive force, which it rarely is. The damping effect is negligible already at two octaves above the resonant frequency.
Damping factor became a buzzword in the early days of solid-state amplifiers because it was something that tube amplifiers did "bad."
If damping factor was relevant for amplifiers, then transconductance (current) amplifiers should be really, really bad. They are not.
Damping factor is marketing. It is at home with Stereophile and the other audiophools. You know, the "golden ears" who claim they can hear the "sonic characteristics" of different metals (usually copper, silver and gold) in connectors and switches. Silver is usually said to sound hard or cold, and gold warm. Whereas copper sounds neutral. True story.  — Preceding unsigned comment added by 89.253.73.146 (talk) 22:13, 14 January 2014 (UTC)
thread_title:  Damping factor is not a relevant factor 

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thread_title:  External links modified