This comes up when I try to send the edit
Riddle me this....
It was recently suggested to me that by reversing the polarity of two stereo
speakers it will readjust the depth of field in your soundstage.
In case that is unclear- If a voice was perceived as being one foot behind the
speakers and you swapped the positive to negative on the terminals of both
speakers it would make that voice move to being perceived as
one foot in front of the plane of two stereo speakers.
Has anyone heard of this experiment and what can you
share about it?
44 responses Add your response
EDIT: Audiogon system would not let me edit just a few minutes after posting...
Edit: Using a kick drum, as an example, when the kick peddle strikes the drum with force it will produce more powerful sound waves by the cone when the signal transient is positive. A negative transient signal will caused the voice coil to pull the cone inward, sucking back. Therein less attack energy is at play. .
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The term absolute phase just confuses the discussion. Signal Absolute Polarity is the terminology that should be used, imo... A normal positive transient signal will cause a driver's speaker voice coil to push the cone forward. A negative signal transient will cause the voice coil to suck the cone inward. Using a kick drum as an example, when the kick peddle strikes the drum with force it will produce more air sound waves by the cone when the signal transient is positive, than inward sucking back, fed by a negative transient signal. The OP's question was about reversing the speaker cables polarity at both speakers. Will it change, alter, the sound? Yes... But not everyone can hear the difference. Can it be measured? Yes... As for the chain of normal absolute polarity it starts with the source material and goes through all the electronic equipment to the connected speakers. At any point in the signal chain if the absolute polarity is inverted then the final product feeding the speakers will be inverted. If the speakers are designed to be feed with a normal absolute polarity signal then if the polarity is inverted feeding the speaker the driver cone will suck in. Yes there are recordings where the recording engineers didn't make sure the polarity was the same throughout chain. Note I did not say a normal absolute polarity chain. Some recordings have an inverted absolute polarity chain. And the recording engineer was aware of it. In an inverted absolute polarity recording, if the audio playback system electronics is normal absolute polarity and is maintained connected to the speakers, then the polarity at the speaker drivers will be inverted. The bass driver will suck in. Not push out when the kick peddle strikes the drum. Can it be measured with test equipment? Yes it can... Read any published articles by the Late Doug Sax on absolute polarity. He made sure the polarity was keep the same throughout the recordings. Though the final product was an inverted absolute polarity. This note on the inside cover of a Sheffield Lab-5 LP:
I remembering reading an article years ago where Doug Sax was asked why his recording polarity was inverted? He said, (just going from memory), it was not intentional it was caused by a piece of equipment in the recording chain that inverted the signal. He was then asked couldn't he have corrected the inversion? He answered it would take more electronics in the signal chain and that could/would degrade the sound of the final product. Just going from memory I remember reading the Late Frank Zappa recordings were also recorded inverted polarity. Why? I can't remember why. Bottom line: If you have an on the fly Phase/polarity switch on your preamp or DAC it pretty easy to check which way sounds the best to your ears when playing a well recorded, sounding, LP or CD. It's that easy... . |
Have vocalists and instrumentalists also learned to record in phase with each other.? My point is if one prefers one phase vs it’s opposite it’s possibly because one is focusing on one aspect of the performance, eg, the vocalist in an ensemble. The answer to my rhetorical question is there is no difference between switching phase 180 degrees in balanced analog mode vs digitally. Except in the latter case the signal has to be reconverted to analog after phase is altered. |
In the analogue domain it‘d have to be mechanical and thereby more accident prone, I guess…Where polarity is messed up during recording, there‘ll be a change in degrees with in most cases one setting preferable. Since the advent of hi-res audio, polarity consistency seems to have moved into focus for recording engineers. |
Explain to me why the phase switch ought to be in the digital domain, as opposed to the analog domain in a fully balanced analog circuit, where ground floats. That's assuming of course that one only wants to be able to change phase by 180 degrees. If one wants to change phase by other parameters, e.g., 90 degrees, 270 degrees or etc, then of course that is best done digitally. But here we are talking about the effect of changing phase by 180 degrees. My ESLs are full range with no crossover. Is that phase coherent? |
It‘s precisely the initial pulse of the wave that defines phase, or for the purposes of this discussion more accurately polarity. Think of a wind instrument being blown rather than sucked ( in analogy to a speaker Diaphragm moving out rather than being sucked in with the corresponding air flow. And it is audible despite what certain theorists claim ex cathedra. Just as an aside: this is the major advantage of a point source over multiple speaker units interfering with each others‘ phase. |
@stringreen ....a mailbox....(but not limited to corners for quite awhile) |
By the way as an aside i like a lot one of the best recording sound company : TACET only tubes recording... A german recording company using ONLY tubes for recording process... The differences is staggering in my audio system ( S.S. amplifier and dac with TOP headphones though 😊) .. I listen to Haydn quatuor with Auryn Quartet... and also Vivaldi four seasons . Polish Chamber Philharmonic Orchestra This cd is one of my best testing sound cd... my best recording ever with one mic. Sound Liaison albums .. https://www.youtube.com/watch?v=KiZ13MIx6CA&t=68s https://www.tacet.de/main/seite1.php?language=en&filename=tubeonly.php |
Many factors are at play... So much than most people dont realize... Your point about microphones is really good point... Why "sound liaison" recording album are so good ? They used ONE MICROPHONE... https://www.youtube.com/watch?v=lQtwN4zO8is
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@mahgister Thank you for that long quote. I won’t rise to the bait about double-blind testing as I can see it applies only to subjective listening tests here. I am fascinated by the information about the eighth cranial nerve, however. It seems to imply we live in a half-wave world, but on thinking for a moment I realise that just because the hair cells in the cochlea trigger on the positive phase, it does not stop them from faithfully reporting to the cochlear nuclei the whole waveform. And when brainstem auditory evoked potentials are recorded, they are indeed whole positive and negative waveforms. Now that would imply only a difference on the first oscillation of a musical signal when phase is reversed, but if the double-blind test says we can tell the difference there must be more to it. Interesting stuff! It makes me wonder if the reason that some uncomplicated recordings (I mean a Blumlein pair of microphones, not post-processing or manipulation, like the old Opus 3 recordings) sound so good because there is no opportunity to introduce various tracks that are out of phase? |
The effect can happen to an extent if your speakers are phase coherent. Ever turn binoculars around and see how things now seem more distant than the usual close up? Reversing polarity of both speakers has that kind of effect. But, its more like hearing what the nearfield mics pick up situated right next to the instrument vs listening to music in a room with some distance. That's what I perceive on my system. |
antigrunge, I hope you and anyone else will get the point that I don’t claim phase makes no difference. Please pay attention to the double negative in that last sentence. I do claim that (1) I, and everyone else who has been subjected to double blind testing for phase sensitivity in my listening room with my dipolar full-range ESLs, cannot hear any difference, and (2) I am not convinced by any argument I have read anywhere, no matter how erudite are the discussants, that changing the phase of an audio system by 180 degrees necessarily ought to make a difference to the listener. Get that last point too.... I don’t see why it ought to make a difference, because there are many counter-arguments that seem also valid and which would lead to the conclusion that phase reversal (of both channels) would just as likely make no audible difference. Seems to me as soon as you have two or more sound sources on one recording (e.g., single piano plus single human voice), the importance of phase in the listening room begins to break down, because the phase relationships of the sounds emanating from those two or more sources is not going to perfect, even if they were recorded using one microphone. Of course, if you are listening for the voice, and if you have "correct" phase for the voice, then that might sound "better" than optimizing for the piano. Dunno. For the many who say they do hear a difference, how do you know that the difference you hear has anything to do with changing phase? You might have a dirty phase switch or when you switched speaker wires, maybe your new connection is better or worse than the original because you tightened down the connector with such conviction. There’s also expectation bias, etc. Jea48 tells some other guy to listen for himself and then provides three URLs that take you to arguments FOR the importance of absolute phase. Better to listen for yourself first. |
Agree...
Standouts where a definite difference could be heard? Jenifer Warnes, "The Hunter" Diana Krall
Use good CD recordings. Best solo passage instruments to listen to: Horns. Trumpet and saxophone. Percussion : |
I think the same as you... It is a big mess... No need to disagree with me on this... 😉
And i want a digital switch for polarity in the digital domain too...
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On this one I have to unfortunately disagree with you both. In my experience somewhere around half of all recordings are polarity inverted. While that means, that it doesn‘t matter which way you connect your speakers, the actual playback will be out of polarity about half of the time. That‘s why having a polarity switch in the digital domain is so highly desirable. It is actually an advantage of digital over analogue to be able to correct this, and: yes, the differences on a decent system are very audible. BTW: @mahgister‘s explanation as to why is by a country mile the most lucid I have encountered on the subject. |
I am very happy that someone get the point in relation to my dicussion with Amir and the time dependant non linear way the ears works... Conditioned by engineering simplistic psychoa-coustic theory going back to Helmholtz many objectivist underestimate and dont know how the ears work , nor what a sound is ultimetaly...( i will not go there for the moment ) I am not a specialist at all... I only read about all that and it is plain to see that most objectivist had no idea of what they talk about when it is not about their measuring components toys.. For the phase problem i think lewm is right... I cannot impose my opinion here because i dont know, i dont have the Wood effect book anyway and i am not competent enough to contradict lewm , i think he is right anyway ... 😊 My best to you...
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@mahgister i just want to say that you gave an exquisite explanation of the phenomenon. Even though I am not a physicist, the terms and relationships of the effect were clear. More importantly, you were able to draw a parallel with wider debates in the audio sphere. |
....in short: Reversing your phase may pervert your stage...something like that...;) There was onceuponatime a means of crosswiring the L & R channels that didn't seem to indicate 180ing one or the other, but was purported to 'nifty things' to the stage....and wouldn't cook ones' amp... If anyone has a better SSD between ears in regard to this, chime in... (I already sift enough leisure into this digital sandbox....*L*) |
I suggest you try it and listen for yourself. Here is some reading material for you: https://forum.audiogon.com/discussions/preamp-inverts-phase-question https://forum.audiogon.com/discussions/amp-inverted-or-non-inverted-phase http://www.6moons.com/industryfeatures/polarity/polarity.html https://www.enjoythemusic.com/magazine/rickerinterview/ricker9.htm . |
The question is what is "absolute phase" in reproduced music where the music itself has been recorded using several different microphones, set up usually without regard to their relative phases, and is then played back through speakers with crossovers and drivers which are a further source of phase error even including sometimes 180 degree differences in phase, and then into a room with reflections that further alter phase relationships. It is one thing to say absolute phase makes a difference but quite another to apply that principle to the reproduction of music in a typical home environment using typical source material and multi-way loudspeakers. And anyway even after all that, the question is only whether a particular individual can hear a difference. It is not necessary for me to deny there is a difference in order for me to report I cannot hear a difference. I attribute my failure in that regard in part to the fact that I use full-range, crossover-less dipolar speakers. (In a dipolar speaker there is rearward radiation of the same magnitude as the forward radition that is 180 degrees out of phase.) And to test my own acuity, I have asked others to sit in my room while I switched phase by 180 degrees under conditions where the tested persons were blinded. No one I have asked to perform this test can hear a difference in my room through my system. And finally, I think we all can agree that the actual question posed by the OP, whether a point source is perceived to relocate precisely in space with respect to a 180 degree alteration of phase. The answer is for a particular listener it is possible a difference in soundstage is perceived but not a difference that can be described so precisely as described in the OP. At least that is my answer. |
Very interesting , i underlined the passage which is very important for me : https://www.stereophile.com/content/absolute-issues-page-2
« Absolute Phase Clark (footnote 6) makes absolutely clear his position on the importance of absolute polarity reversal: "Whoever cannot recognize Absolute Polarity, shall be deemed SUPERFLUOUS," which seems a little too absolute, considering that JGH is one the least superfluous audio commentators around. But why should polarity matter? If an acoustic compression at the original event is reproduced as an acoustic rarefaction when the recording is played back, electrically there should be no difference at all. Additionally, the eminent acoustician Helmholtz stated in 1862 (footnote 7) that "the quality of the musical portion of a compound tone depends solely on the number and relative strength of its partial simple tones and in no respect of their differences of phase," and many people feel that Helmholtz said all that needed to be said on the subject.
However, as documented by Johnsen in The Wood Effect (and also in an article I wrote for HFN/RR in 1980, footnote 8), nearly all the academic work performed since Helmholtz suggests that the human ear can detect acoustic polarity differences, although all research indicates that the effect is sometimes subtle. (The book’s title comes from work carried out in 1957 by Charles L. Wood of the Defense Research Laboratory, who found that a sinewave, clipped on one side of the time axis only to render it asymmetrical, took on a different timbre when its polarity was reversed.) Work by Stanley Lipshitz in the late ’70s (footnote 9), using carefully organized double-blind testing, confirmed that a reversal of absolute signal polarity will be subtly audible on music to a 99% confidence limit! (footnote 10) (Indeed, it is one of the few things that can be reliably detected with double-blind testing.) There is even a mechanism agreed upon as to why the ear should be able to detect the supposedly undetectable. The nerves attached to the frequency-discriminating hair-cells in the inner ear only fire on the positive-going parts of the waveform, indicating that the ear acts as a half-wave rectifier. It will thus produce a different output to the brain on asymmetric signals if the absolute polarity is reversed. A music signal, unlike a sinewave, is not symmetrical about the time axis, other than that over the long term there are equal amounts of energy on either side, and it would be expected that if an original compression was reproduced as a rarefaction, you would be able to hear it. What does it sound like? "Wrong polarity is the muffling distortion," writes Johnsen, and it seems generally agreed that to listen to a recording with the wrong polarity is to suffer from a lack of realism, a lack of body to instrumental tone, a lack of integration within the soundfield, and less natural-sounding applause. Unfortunately, as there is no necessity for engineers to preserve absolute polarity during the production of a recording, a recording has a 50% chance of being wrong. In fact, as reported in The Wood Effect, which includes considerable documentation of the subject, Japanese-pressed LPs even have alternate tracks in opposite polarity! The aspect of Clark’s book that I found fascinating, and one which ties in with the general theme running through this essay, is that despite the evidence for its existence, despite there being almost no opposing evidence, the engineering establishment seems to dismiss the matter of the ear’s sensitivity to absolute signal polarity. (One would almost think that we were talking about amplifier differences here.) The Wood Effect contains a thorough examination of the apparent philosophy of the Audio Engineering Society, as expressed through the choice of papers to reprint in its Journal. Johnsen implies strongly that only the results of research work which conforms to orthodoxy will benefit from a wide dissemination in the JAES, and that that orthodoxy sticks strictly to Helmholtzian theory in denying the importance of phase effects at all. There is, of course, the notable exception of the published work by Stanley Lipshitz et al referred to in footnote 9—Stanley’s formidable mind brooks very little obstruction in its chosen path—but I don’t think it coincidental that Douglas Self behaves as expected in his E&WW article in attempting to cast doubt on the Lipshitz findings on the audibility of phase errors. Once the door is opened a crack, then it could be pushed open even further, and—heavens!—amplifiers might be found to be audibly different after all! Better to dismiss the whole subject altogether, and if that means dismissing something such as absolute signal polarity that has without question a real effect on the quality of reproduced sound, then so be it. Thus is the thrust of Clark Johnsen’s tour de force, and if you feel that the reality of the matter is not so, then let me conclude with a quotation from the BAS Speaker by David Moran, once of dbx and President of the Boston Audio Society, which also concludes The Wood Effect. It neatly illustrates, in my opinion, exactly how "technical orthodoxy" is more concerned with preserving establishment attitudes than with improving the quality of music in the home: "These are interesting times in audio. The smoke that is blown is now being couched in the language of science, and no longer in the language of marketing. Waveforms of oboes, discussions of room acoustics, etc., with footnotes to the JAES et al., will be given, along with contentions that clarinets will suck instead of blow if speakers are not properly phased—all couched in terms of, ’You’ve heard hype before: this is science.’ " The Wood Effect, by R.C. Johnsen, cost $7.95 when it was first published and could be obtained at The Modern Audio Association, 23 Stillings Street, Boston, MA 02210. It is out of print in 2006 but copies might still be obtainable from the author.»
Footnote 6: The author is a Harvard Physics graduate, with published academic work in the fields of image processing and the measurement of sight objects. He has worked on holography, surveillance satellites, the Mars Lander camera, and the Orbiting Space Telescope. He now runs "The Listening Studio" in Boston and recently founded The Modern Audio Association to advance the state of music reproduction art "without commercial gain or pressure." Footnote 7: On the sensations of tone, H.L.F. Helmholtz; Dover, 1954. Footnote 8: "Listening Tests and Absolute Phase," HFN/RR, November 1980. Footnote 9: "A little understood factor in A/B testing," The BAS Speaker, March 1979, followed by "On the Audibility of Midrange Phase Distortion in Audio Systems" (with John Vanderkooy and Mark Pocock), JAES, Vol.30 No.9, September 1982. Footnote 10: It subsequently emerged that the 99% confidence limit applied to test results using both music and asymmetrical test tones, not music alone.—John Atkinson |
Don’t keep us in suspense. What is the Wood Effect, and what does it say on this subject? I just spent 5 minutes reading about the Wood Effect. This was on another audiophile website in an exchange that took place in 2008. Seemed like the guy who brought it up did not really understand it himself, something about changing phase by 180 degrees at the amplifier/speaker interface, both channels of course. Why would that be any different at all from reversing phase anywhere else in the chain? Then there was a discussion that basically devolved into one of those where believers in the Wood Effect inferred that those who could not hear it are somehow Philistines using inferior speakers. One guy claimed it makes a big difference with Sheffield D to D LPs because they are "phase coherent". Spare me. |
roxy, In your first post, I think you are thinking of the situation where one channel is 180 degrees out of phase with the other channel, in a stereo system. Yes, that causes very obvious problems, and needs to be corrected so that the two speakers are "in phase" with each other. The OP is asking about the situation where you reverse phase on both channels at the same time. Many listeners think there is a "correct" choice and say they can hear important differences when the choice is incorrect. For many boring reasons related to how recordings are made and room acoustics and the nature of crossover networks, I do NOT think there is a correct choice, so long as the two speakers are in phase with each other, but I do think that with many monopolar speakers and depending upon the room, there may seem to be a correct choice to some listeners (not to me in my room with dipolar speakers and using a panel of listeners who were blinded as to speaker phase). To each his own, in other words, in my opinion. The logical extension of my findings for my system is I don't care a fig whether the preamplifier or any other component in the chain reverses phase (in both channels of course). And I would not agree to the OPs proposition that inverting phase in both channels causes the image of the performer to move fore or aft. |
That won’t happen. It’s the same as flipping the polarity switch on your preamp or DAC, which typically changes the sound in ways that some people find inaudible most of the time and a few others other find highly important for musical realism. Most people seem to find it pretty subtle on most recordings. |
