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In Reply to: Pundit/Perfect/Polarity Acid Test....George ? posted by PeAK on January 14, 2007 at 14:30:37:
One interesting element in the polarity discussion for me is the use of several different modifiers of the term polarity. Most common are "absolute" and "relative", but isn't any modifier of the term except "correct" and "inverted" redundant- like saying "completely unique"?
"Relative" especially seems to be meaningless as polarity can not be a question of degree. There is only one relative polarity- something is relative only in realtionship to another thing- inverted is "relative" only to something in correct polarity. I think the term "relative" is some confusion with phase and should be eliminated from useand only "correct" and "inverted" have any meaning.
As well, "absolute" seems childish as polarity is completely in one direction or the other. I find the use of the term "absolute" to have a misdirecting pseudo-intellectual quality trying to bombast it's way to achieve some kind of discount, faith-based science. Dealing in "absolutes" makes it seem like a final answer and is more a TV evangelists' term than something science, which declares nothing as absolute.
In my view, these modifying terms only try to complicate an issue with that needs clarification instead.
If I'm missing something important in the use of these terms- let me know- I'm trying to understand this issue- plus improve my English all the time!
I haven't delved into this subject to a great degree- university courses in physics and acoustics, reading Helmholz on psychoacoustics, this forum, six years at a radio station, around recording, and references in "Stereophile" and I've yet to read a clear description of the sonic effects of inverted polarity and how to recognize them.
" I find the use of the term "absolute" to have a misdirecting pseudo-intellectual quality trying to bombast it's way to achieve some kind of discount, faith-based science. Dealing in "absolutes" makes it seem like a final answer and is more a TV evangelists' term"
I "think" the term was conned by Clark to describe in his words the most representative polarity as described by the
final ear impingement point movements
closests to the live audition "movements". "Absolute", anyone? It gets confusing with multi-track but I guess you take a weighted sum of all the tracks/polarities and assign one reference polarity as closest (least error) to the original live event ear movements.
Take 1:Closed miked "drum whack" front followed by suckout positioned above the drum.
Take 2: Same but with mike below drum. Reverse front (relative to Take 1) followed by reversed suckout.
Which sounds best? Which is absolute? Is the Assymetry reversed ?...Clark/George?
If you measure a drum with a microphone placed above the head, you'll find the initial strike produces a rarefaction. This is because the drum head moves away from the microphone first. If you measure below the head, you'll find it produces a compression half-cycle first. This is because the drum head moves towards the microphone in this case. The two sounds are identical, except for the acoustic filter of the drum body being between the mic in the latter case and beside the mic in the former case. All instruments are this way, in fact, all sounds. There are just as many events in nature that produce an initial rarefaction attack as there are those that produce a compression attack. They sound the same because the human ear/brain interface isn't "wired" to tell the difference.
"...They sound the same because the human ear/brain interface isn't "wired" to tell the difference."
I agree with your explanation in its entirety but my gut tells me the "Absolute Polarity" camp would beg to differ with your last statement.
Yes, but get them in a double-blind test and they'll find their arguments fall to pieces. I suspect they'll be as unwilling to use double-blind tests or will find excuses why they don't work.
...perhaps you'd care to define it for us?
Other, ah, haziness pervades the post:
"Only 'correct' and 'inverted' have any meaning." That's good to know. Ah, but what's "correct"? Love to see a definition of that -- say, on a CD or an LP. Or even a tape. Go on, give it a shot.
"...references in 'Stereophile'." Right. Where the terms are more than unusually confused, for the topic.
Finally: "I've yet to read a clear description of the sonic effects of inverted polarity and how to recognize them." Many of the references in The Wood Effect, as well as the book itself, explain the phenomenon very clearly.
Hope that helps.
In my terms, polarity is "correct" when the transient intiates with a positive signal- a positive pressure wave. This is the only condition that can occur in nature. I suppose we could also call this "natural" polarity. And as this is the condition of sound in nature, and our brains have evolved to be able to interpret sound largely based on the qualities of transients and decay, we know that reproduced sound with the correct initiation of transients will sound more like natural, or acoustic sound.
The other case is a condition of inverted polarity- when the transient intiates with a negative- a rarefaction wave. Inverted polarity is only possible in reproduced sound because an amplifier can power a speaker cone backwards at the initiation of the transient- there is no condition in nature that can do this. Then, if the sound begins with a negative- a rarefaction wave- so it is perhaps also described as "unnatural" polarity, but in my view "inverted" helps visualisation of the condition as the graphic waveform is so useful a conceptualisation.
As I mention, I think "absolute" is not an appropriate modifier of polarity as polarity must be either correct ( as in nature) or it's inverted (only possible artificially). Sound is a physically dynamic system but that system has only two modes with respect to polarity. As there is no question of degree, the fact of two- and opposite conditions. Absolute does indeed mean without question or degree, and so can be applied equally to correct or natural as well as inverted polarity- a sound could be absolutely in the correct, natural state, or absolutely in a condition of inversion. - I.e., polarity natural or inverted may still be called "absolute"- the sound is propagated in one mode or the other. Perhaps I'm missing it's full usage- perhaps it's supposed to be a contrast to relative polarity, where some components are inverted and some are correct, but it seems applied always to mean polarity that is correct or natural.- Am I missing references where it is applied to inverted polarity? That's why I would prefer to apply terms that are more specific to describing the two opposite conditions. Absolute is in this case is ironically too vague!
And, in physics- the term "absolute" has a specific application in which the application to polarity seems at first to be applicable but looking further seems incorrect on two levels. In physics, absolute refers to certain measurements relative to an agreed foundation base that is "absolute". The use of absolute has no component of being natural or inverted. In polarity, there is the temporary condition where the pressure waves pass though the necessary transistion from positive to negative pressurere. To move from a compression to rarefaction- the pressure will have to move through the "0" line looking at a graphically displayed waveform. So, polarity, like temperature, and time might claim an absolute- analogous to "absolute zero" in which there is no Brownian motion- as that exact point at which there is neither positive nor negative air pressure. But, agin, if we accept a condition of an absolute base line, the term would still apply to natural polarity and inverted- they are both still measurements taken from the same base line pressure equilibrium conditon. Further, if nits are to be fully picked, the stasis point is always relative to air pressure that is fluctuating all the time- there is no fixed point of stasis that is absolute because the base reference point can change- is always changing, and we know that conditions of temperature that affect density mean the wave propogation is affected and there is a set temporary base line condtions. Can polarity be “absolute” if the wind is blowing? And I think science is more than reluctant to use temporary and fluctuating base line conditions when describing something as “absolute”. I'd be glad to know of cases where absolute is applied in the other respect.
It's just that applying the term absolute with regard to polarity has more a component of suggesting that it is absolute in correctness- without question, has an finality to it- and this is so rarely applied in science- does 2+2=4 absolutely- in all Dimensions? Are Newton's Laws absolute or does Relativity modify them?
When someone tells me something is perfect, the best, or absolute, I look into the depth of the pronoucement- it can of course be true if the commenter's consideration is only in the realm of personal parameters and terms, but it seems either desperate to convince or the utterance of someone who can't tolerate the insecurity of degree. Absolute by definition precludes a question of degree or modification and with the subject of polarity seems designed to also preclude discussion- an attempt to a faith-based just trust me science.
Part of this is a semantic rebellion to the bombastic but obfuscated pronoucements of our friend and obsessive trademarker, who seems to want a kind of absolute control of the polarity issue, while maintaining a level of mystery- the "childish" aspect I mention is partly a reaction to speaking of absolutes in the presence of what seems still a chaotic, developing science at certain levels- no agreed methodology and somewhat random and/or personal terminology.
Meanwhile, to find a bit more grounding on this issue, I've devised a simple home audio system polarity tester that seems to yield easily discernable results so far and I'd like to try it on several more sources and CDs. So far, I’ve only looked at mono signals to simplify the issues. When I know which system setup and sources are in "correct" polarity then I can begin to tackle the issues of what effects inverted polarity and sounds that contain some elements that are inverted mixed in. According to our friend just about everything is inverted, but so far I'm finding most everything around here correct. I wish I had my old 78's and wind-up Columbia here as it occurs to me that all mechanically recorded disks- and wax cylinders too, must be in correct polarity throughout- and correct relative phase for that matter.
Certainly, I should like to read more of your descriptions of polarity effects and issues, I've only read your "Positive Feedback online" no.1 article. I don't think Helmholz ever tackled polarity as he lived before inverted polarity was possible to make !
Confusion? Thy name is audio !
Pity for him the complete territory had been staked out already by 1988.
Your essay, while very thoughtful -- and incisive in parts -- fails to recognize a factor that makes everything else fall into place. I shall enunciate that factor later, so instead of dealing with your points one-by-one (my usual practice) I'll do a couple of highlights.
It's just that applying the term absolute with regard to polarity has more a component of suggesting that it is absolute in correctness - without question, has an finality to it - and this is so rarely applied in science - does 2+2=4 absolutely - in all Dimensions? Are Newton's Laws absolute or does Relativity modify them?
I must chastise you here for a straw man argument. First, yes, a certain "finality" does apply: Given our either-or, 180-degrees situation, we face either an *in* or an *out* condition -- absolutely! Second, the terminology has been around for decades, so howevermuch it disturbs you, unless you can come up with a more-appropriate-to-you term and popularize it, you'll just have to live with it!
The "childish" aspect I mention is partly a reaction to speaking of absolutes in the presence of what seems still a chaotic, developing science at certain levels - no agreed methodology and somewhat random and/or personal terminology.
Again the straw man; the "science" -- or at any rate the engineering -- of the situation is highly developed, as any reader of The Wood Effect knows. Perhaps I should say, surprisingly highly developed -- you just don't know it yet.
Meanwhile, to find a bit more grounding on this issue, I've devised a simple home audio system polarity tester that seems to yield easily discernable results so far and I'd like to try it on several more sources and CDs. So far, I’ve only looked at mono signals to simplify the issues.
Good man! Polarity is after all a MPE -- in acoustics terminology, a Monaural Phase Effect. And that's also where the saga of polarity began, in the early Fifties, as reported in JASA.
When I know which system setup and sources are in "correct" polarity then I can begin to tackle the issues of what effects inverted polarity and sounds that contain some elements that are inverted mixed in.
And here is where you begin to stray. Like Dave Pogue (who chose to evade the issue with a personal insult), what do you define as "correct"? Say, on an LP or a CD?
According to our friend just about everything is inverted, but so far I'm finding most everything around here correct.
Aha! And here I may launch, for that single sentence reveals the confusion in many people's minds about the topic to hand.
But first, this comment: You're just as wrong as George. You'll see.
Now, the Abstract from the referenced book:
Masked by random combination with other distortions in the music reproduction chain, an unsuspected major contributor has lain hidden: Aural sensitivity to ‘phase inversion’ — the Wood Effect.
Music normally creates compression waves. Electronics, however, often invert that natural, positive polarity to unnatural, negative rarefaction, thus diminishing physical and aesthetic impact. The term Absolute Polarity uniquely describes the correct arrival to the ear of wavefronts from loudspeakers, with respect to actual musical instruments.
Wrong polarity, when isolated, is obvious to everyone. Its present neglect results from habitual disregard for phase response, especially in loudspeakers.
Perhaps you see the quandary already? There are three distinct areas where "polarity" operates.
-- As inscribed on a tape, record or disc.
-- In a piece of electronic gear.
-- In acoustic space.
On any recorded medium -- take anything you like from the last 100 years -- my challenge to you (to everyone) is to situate for us a rule by which a particular swing of voltage (say, a groove excursion to the outside) must invariably relate to a positive-going voltage at the microphone output. (Again, thinking monaurally makes it more transparent.) If you can locate this standard, I'd like to know. But whatever the answer, you see that polarity can be inscribed on a recorded medium in either fashion.
With electronic gear a unit may invert its output from the input, or not. Inversion here is a knowable, easily overcome, mild defect and need concern us no further.
Ah, but now, acoustic polarity! I haven't seen that vital term employed in this particular thread, more's the pity because that's where the term "Absolute" arises. After all of the possible foregoing difficulties it still remains to the listener to establish whether the final result at the ear mimics the production of real acoustic instruments. And here it is that the term "Absolute" must be used to differentiate from "correct", because as you must by now have seen, there is no "correct" for recorded media or gear, even though many may think there is.
Yourself, for instance.
Regarding the actual distribution of the two polarities on recorded media, we have a binary situation here that's reduceable to a simple calculation. Thus I shall leave it to the reader to find the solution when the two polarities are (as is the case) randomly distributed. (Don't forget to integrate over both space and time, and don't leave out 78s!)
Cheers to ears!
In case anyone missed the reference, this was the year that Clarke "Mr. Modesty" Johnson published 'The Wood Effect', his "tome" on the subject.
it frankly has nothing to do with Absolute or Inverted Polarity.
And it describes the relationship of the two channels "relative" to each other. The term is correct and properly used in audio terms.
I appreciate the clarification regarding "relative" polarity, which I felt was sometimes being used for relative phase. Yes, because of multi-tracking in recording, there can be inverted polarity relative to the other tracks. I would think this factor- as mixing buries the inverted track among those in correct polarity, would make detecting inverted polarity much more difficult.
... of distinguishing them, along with 0 and 180 degrees. Absolute and relative are problematic terms, I agree.
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