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In Reply to: Yes a POLARITY STANDARD does exist... posted by Jacques on May 26, 2006 at 12:54:50:
But when was the last time you saw it on a new CD?Just because there's a "standard" doesn't mean it's infallible. You don't really understand the complexity of the issue.
Follow Ups:
But when was the last time you saw it on a new CD?
What does it has to do with the topic of this thread: a polarity standard does exist, contrastingly to a previous post statement. The fact this standard or furthermore another one is widely used or not has nothing to do with the topic. Fallacy.
Just because there's a "standard" doesn't mean it's infallible.
How could a standard be infallible? It is not a being nor an algorithm: it does not make decisions.
Some mismatch of semantic categories here.
This standard, as all of them just defines a common way of doing things.
Will it solve the issue or not is a completely different topic.
You don't really understand the complexity of the issue.
You're offensive now.
As for you, to complete your mastering the complexity of the issue , maybe some courses of logical thinking would be welcome ?
With a good manners option? ;-)
The "standard" that you are clinging to is this:AES26-2001: AES recommended practice for professional audio -- Conservation of the polarity of audio signals
A recommended practice is by no means a standard.
As for my reference to the defunct SPARS code, if you understood why the SPARS code was meaningless, then you might have a little bit of insight into the polarity issue.
A recommended practice is by no means a standard.
Stricto sensu, no. It is aimed at becoming a mandatory standard if it gains acceptance. So for the word standard .
However, the fact this "best-practice document" (as we call such documents in EU jargon) exists proves that the guy who wrote :Neither the AES, nor the RIAA, nor the DIN,nor the specialist press has lifted a finger to establish or evenis flatly wrong, which was why I opened this thread, and which is funny from a self-appointed polarity guru.
suggest a standard for recordings or for playback equipment.
As for my reference to the defunct SPARS code.../... which I don't know, so i'm clueless about it. So, let us better speak about flaws I see in current AES26.
The notion of absolute polarity along the whole chain from the sound source to the customer's speaker only has a meaning for DC! Only for DC could (not can ) you define how an air pressure increase at the mike has to translate into an increase of pressure in the listener's room. Obviously, it is of little interest, but it is the way it is specified in AES26.
Above DC, you have to count with phase shifts, would they be be frequency linear( FIR structures, analog filters utilizing tapped delay lines -does it exist?It could- ) or not.
Since musical signals spread onto many individual frequencies, would they be harmonically related to the fundamental or not, a phase for this signal cannot be defined, not to speak about keeping it untouched through the mixer, the outboard gears etc.
Even without electronic gear between the source and the listener cannot phase be kept untouched:
You listen to a piano. You recognize it, its manufacturer, its year of manuf'g, who plays it. Now sit down one meter behind your previous place.
You hear the same piano, would make the same fine conclusion about its manuf'g and its player. In fact, you adapted instantly to your new position.
However, the acoustic pressure waveform is completely different in each case. Reflexions are different, beams from diffractions around the piano's edges are obviously received differently etc. And those reflexions and furthermore diffractions are frequency dependent. Which gives way to a large phase incoherency between the two signals, the one at your first place, and the one at your current place. But you hear the same thing.
Obviously, this feature of hearing is easily explained by the way it is done, the (phase insensitive) travelling wave system is the cochlea,the critical bands it defines etc.
It is also a question of survival, BTW, and a species with phase sensitivity (who, as a predator, would not be able to recognize a prey's scream, since this recognition would depend upon distance and acoustic envrironment; and as a prey would be equally unable to hear a predator until too late) would soon go extinct.
A caveat however: at very low frequencies, since the hearing is said to resolve the acoustic pressure edges, one could think some kind of phase accuracy is needed.
However, what we need here is time-delay coherency, in order the edges from low frequency instruments are resolved in the expected synchronized manner. The phase coherency itself seems clueless in this matter.
While writing this, I'm modifying the Sub/Low delay position in my active crossover. When you stay in the listening area, not so far away from the speakers, you just cannot hear any difference. Elsewhere, you can, since the "delay" feature makes the speakers box have its "loudest plan" (sorry, don't know the exact english wording) tilt from any position to horizontal, at frequencies around the xover's.
The delay setting itself is not really a delay, but instead a pass-all filter with linear phase only around its corner frequency.
then you might have a little bit of insight into the polarity issue
How arrogant a wording! Maybe you need it to heal from some traumatic event that occurred to your ego centuries ago.
I won't object on that, but please, don't use this forum as your therapy group.
( I would add this is the aim of the Propeller Head Forum ;-)
To conclude, I do think that AES-26 is of limited meaning, not to say meaningless. The funny part is that its authors (unknown!) are way conscious of it when they write ( note 2, page 5, paragraph 4.1 )Some audio processors may produce phase shift or process a signal so that the signal waveformI like the some ...
is lost and only the signal spectrum is preserved. In such systems, polarity has little if any meaning.
Quod erat demonstrandum.
avandia+drug+
AES calls all of its "standards" recommended practices.
The argument that the possibility of phase distortion (as Clark would call it) relegates polarity moot is downright ludicrous. It may relegate phase inversion inaudible, but certainly not irrelevant.The use of phase to blur the polarity issue is also disingenuous. Polarity and phase are two distinctly different issues that, while inter-related, have wholly different causes and resolutions.
To say that because the AES has issued a recommended practice document that attempts to establish uniformity in transducer or A/D-D/A polarity then there is a standard to maintain absolute polarity is patently foolish. Inversion of polarity is not a component problem, it is a system problem.
I would also dare venture that comparing acoustical phase changes to electrical phase shifting and saying that they are both aurally perceived as identical is akin to saying oranges and lima beans taste alike. Homey don't play that.
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