[James Romeyn]

The only "truth" being sought is:

People who have done the test.  If you think your own system is NOT whatever you call "good", don't vote.  You can do the test, just don't vote.  

People vote.

That's it.

The rest is just whatever it is, but completely irrelvent to this pole.  If the result is let's say 75% yes, it's still 75% yes even if someone says yes actually means no.  Or that a yes & no vote are the same, or almost the same, or that their vote was bought, or fill in the blank.....  

The 25% can say the 75% are all deluded, & that opinion is fine.  But it doesn't change the fact that 25% is a minority vote & 75% is the majority.  

[Kevin Haskins]

The only "truth" being sought is:

People who have done the test.  If you think your own system is NOT whatever you call "good", don't vote.  You can do the test, just don't vote. 

People vote.

That's it.

The rest is just whatever it is, but completely irrelevant to this pole.  If the result is let's say 75% yes, it's still 75% yes even if someone says yes actually means no.  Or that a yes & no vote are the same, or almost the same, or that their vote was bought, or fill in the blank..... 

The 25% can say the 75% are all deluded, & that opinion is fine.  But it doesn't change the fact that 25% is a minority vote & 75% is the majority. 

It also doesn't change the a majority has nothing to do with finding the truth.   A majority (even if you get enough people for meaningful sample) only means that a majority of people believe it.   If you took the same sample at lets say an AES meeting you would get a different number.  The results vary with a number of variables and it could change as more knowledge becomes available about a subject.   There are any number of physical things that the majority of people have believed and are false.   Both moral things (slavery, women's rights, democracy etc..) and physical properties (make-up of the universe, physical laws, composition of matter etc..) all have been held as common knowledge and the majority opinion has changed over time.   

I respect your opinion and your intent on finding the truth in the matter but I don't think a poll is going to achieve that end.

[Joules]

Ok - I have a DEQX running a three way system. The DEQX is supposed to correct for phase and group delay with high order crossovers. The DEQX PC control panel also has a easy to click button to reverse the polarity (phase) on each driver, while playing music. So clicking back and forth I can definitely hear a difference. But not every recording shows this difference.
This is a very interesting thread. I'd like to learn more about this and I'm curious to hear about other peoples experiences with their test results. I'll try and make sense of it later.

[Kevin Haskins]

Ok - I have a DEQX running a three way system. The DEQX is supposed to correct for phase and group delay with high order crossovers. The DEQX PC control panel also has a easy to click button to reverse the polarity (phase) on each driver, while playing music. So clicking back and forth I can definitely hear a difference. But not every recording shows this difference.
This is a very interesting thread. I'd like to learn more about this and I'm curious to hear about other peoples experiences with their test results. I'll try and make sense of it later.

If you click back & forth with individual drivers in a multiway system you are changing something that is very important for proper performance (frequency response).   If you click to change the polarity on ALL drivers then you are changing the absolute phase we are talking about. (all three drivers on both loudspeakers).   When you change one driver in a system it causes FR problems at the crossover frequency.   There are many times when people don't even recognize this (20-40db dip at crossover depending on the design, program material and setup).   

Since you have DEQX I assume you can measure to confirm your not getting a FR problem at crossover.   That would be the best way to confirm your changing the phase of both drivers.   You should get the same FR measurement no matter which phase you choose.   You get the same phase measurements in the completed system along with the same distortion measurements also.   All you should be changing is the polarity of the output to take the poll.

[Joules]

I'm sorry - let me be more specific. I, can and do, change the polarity (phase) on all 6 drivers to compare absolute polarity. I can assure you that inter driver phase is correct. The DEQX and the rest of the system is set up and working correctly. But I can't prove that here and now. You'll have to have Faith in me.   

[Kevin Haskins]

I'm sorry - let me be more specific. I, can and do, change the polarity (phase) on all 6 drivers to compare absolute polarity. I can assure you that inter driver phase is correct. The DEQX and the rest of the system is set up and working correctly. But I can't prove that here and now. You'll have to have Faith in me.   

Ha!   I'll take your word for it.   

Those contraptions are fairly complex though.   I'm not sure I'd trust anything coming out of a signal blender like that machine.    

[daj]

Posted on my web site, quoted below. Comments welcome.

Three reasons why absolute polarity might at least in theory affect the sound.

1) Ear as rectifier. The ear responds only to increases in pressure, meaning it operates something like a half-wave rectifier. (Brain fills in missing negative-going half wave.)

If one views a time vs. pressure plot of sound waves from a single musical note, its harmonics generally make the waveform asymmetrical in time. From the point of view of a rectifier, where only the positive-going half of the whole wave gets through, this means the waveform can be right side up or up side down, depending on the phase. One can imagine the sound seems more natural when hearing the half that normally would be reaching the ears directly from a live instrument, rather than the half that would reach the ear only after being reflected from a surface.

If this is valid, then there will be a problem with both the first arrival sound from the speakers and the reverberant sound, since the brain will be getting the inverse of what it would be expecting from both. In other words, when it takes a reflection to invert the sound into the correct, pre-reflection sense, the brain may be not as easily fooled into thinking the sound is live.

A strong argument against this is that there is no absolute reference available for determining whether the initial phase is inverted. It seems more likely that the brain takes the sound it gets directly from the sound source, whether this is an instrument or speaker, and uses it as a reference that helps incorporate the subsequent reverberant sound into its perceptions of source position.

On the other hand, as alluded to above, the sound from many instruments lacks symmetry in time. For instance, as a bow is drawn across a violin string, the string is gradually stretched, then suddenly released in a periodic fashion, producing vibrations with asymmetrical rise and fall times, whereupon these vibrations resonate in the violin body. This produces sound that has an uneven waveform. One who is accustomed to hearing live violins may thus expect to notice a change in the timbre when phase inversion increases the relative abundance of the steep or less steep half of each cycle.

The question of which way sounds more natural or convincing is probably moot, though, because the violin body and its position cause all kinds of phase altering effects, changing the degree and sense of asymmetry practically at random. Techniques used with other musical instruments, such as clarinet, take advantage of their directivity in combination with reflections from the floor to alter their timbre while playing. The combined sound can hardly be said to have anything like phase invariance.

2) Time coincidence of sound from bass drum hits. The subsonic impulse that accompanies a live bass drum hit normally arrives at the body as a pressure peak that coincides precisely with the arrival of the higher frequency sound from the drum stick striking the drum head. In theory, if a speaker is inverted in phase, the push that recreates the impulse will not coincide exactly with the audible sound of the strike. Depending on where the microphone is situated, the impulse will arrive a couple of dozen milliseconds too late or too early. Too early? It could be too early when the drum head is struck and heard from above the drum, which creates a pressure trough that wil be reproduced as a pressure peak when the phase is inverted. If any of this is perceptible, there would be a certain amount sensory dissonance as a result, and that would reduce the credibility of the sound.

There are two arguments against this point. One is embedded in the explanation above, which is that drums normally emit an impulse out of phase with the whack of the stick when heard from above, and in phase when heard from below, and the actual sound from the usual position off to the side is a combination of both. Sound with randomly combined phases can not possibly have polarity, so that inverting its phase can not possibly matter. The other counter-argument is that sensing this delay would involve two separate, unrelated senses: the body's thump sense and the ear's hearing. It is not reasonable to believe that these senses are tightly coupled. Further, the delay will be something like 20 to 40 times the longest period that the ear is sensitive to.

3) Relative left-right delay in a stereo system: The ear relies on loudness, timbre, and relative time delay to help locate the position of a sound source. Louder on the right came from the right. Muted in timbre or having lots of reverberant (multipath) content is farther away. Bright and clear is closer. Sound that arrives at the right ear a few hundred microseconds earlier than the left came from the right. (FWIW, humans are most sensitive to delays from about 100 to 1000 microseconds, which is mostly a result of what is possilble given the particular distance between our ears and the time resolution of our auditory systems. Sound takes about 500 microseconds to traverse this distance.)

In a stereo system, most audiophiles know that inverting the polarity of one channel "smears" the image. It essentially swaps the relative left-right phase delays, but without swapping the relative loudnesses. This is bound to cause the brain some significant processing troubles. Instruments at center stage will still sound more or less okay, since phase and loudness will more or less line up, but sounds that are positioned off center will sound less natural and their positions will be less determinate because the brain will be getting conflicting cues.

Now consider the case when both channels are inverted. This produces an equal half cycle delay in both channels. The relative phase between the two channels, and the loudness and timbre are all conserved. It's easy to conclude that there should be no audible effect on anything, including the sense of position. But this analysis ignores something important, as in that old riddle about a fatal accident on an international border, i.e., which country should bury the survivors?

An equal half cycle delay on both channels is not the same thing as an equal time delay unless the same exact signal is played on both. Instead, delay is proportional to frequency. Lower frequencies, which have longer cycles, will have longer delays.

Consider the effect on our position senses when a 500 Hz sound from one side is delayed three times as long as a 1500 Hz sound from the other, and the harmonics of each note are delayed by different amounts.

For illumninating contrast, all-pass filters create a time delay, which is how they are useful for correcting a phase problem at a particular frequency. With an equal time delay, the phase shift is proportional to frequency. For instance, at a crossover point, one will want the phase of two drivers to match, and altering the phase at that frequency by adjusting the time delay can be crucial to avoiding sonic interference that would otherwise cause an unwanted first order peak and dip in the aggregate response. With an equal phase shift, however, the delay is proportional to frequency. That causes the relative phase of two notes from two speakers to have something other than the original relative delays. 

Unlike the bass drum case, these delays fall within the range where our ears are sensitive to it, where it would be expected to help determine position. It seems likely to at least harm one's sense of how the recorded instrument's direct sound meshes with the ambient acoustics of the recording venue. The relative positions of different instruments may also be affected. Further, changes to the relative time alignment of harmonics may simply not sound as convincingly live.

Okay, so in theory, based on that last point, which I have not heard stated elsewhere as of yet, it may be better not to invert both channels. In real life, though, does it matter?

Some say no, because the signal chain includes different types of microphones in various positions, phantom supplies, mixers, preamplifiers, miles of cable, recording to intermediate media, playback of intermediate media for recording to final media, final playback gear, tone controls, equalization, crossovers, non-coincident speaker driver alignments, etc., which may contain random numbers of phase reversals, analog integrations with the loss of constants of integration, plus plenty of frequency dependent phase shifts.

Though this is not an argument against inverted phase audibility, per se, it seems doubtful that there will be a noticeable effect, never mind a deletrious one, when inverting both channels of a signal that already contains substantially adulterated phase information. It is probably an important reason why it is so hard to find recordings that sound natural no matter how good and scrupulously connected the playback gear is.

On the other hand, some modern recording engineers have implemented carefully arranged, short signal chains coupled to simple, two-microphone or "coincident microphone" recording setups. Actually, this is somewhat of a back-to-the-future situation, implementing techniques similar to those of the old Decca and EMI engineers at the outset of the hi-fi era. There tend to be drawbacks in terms of always getting all the instruments at the right relative levels, but this seems the most likely method for producing recordings that sound natural when heard on sufficiently phase-conserving playback gear.

I'm not advertising here, but if you have not heard recordings produced by shops such as Reference Recordings or Water Lily Acoustics, and you enjoy live performances, then you may owe it to yourself to give one a try. If you do, be forewarned that it will probably not be an "Ahah!" experience, but one that grows on you.

[daj]

I think audibility polls should have more than two choices. Something I haven't heard [yet] might exist. Something I think I've heard might have been imaginary. I'd add "very likely", "likely", "no opinion", "unlikely" and "very unlikely" as additional choices. The majority who are abstaining may, like me, prefer a wishy washy option, the results would have more shades of meaning, and the "no opinion" rate would be a measurement of relevance.

[gonefishin]

   Hi Kevin (Hope you and the family are well )

   I've read all the opinions within the post, but I'm still not certain if you have tried this yet or not???


    thanks...take care!
     dan

[Ektalog]

Those contraptions are fairly complex though.   I'm not sure I'd trust anything coming out of a signal blender like that machine.    

My feelings, exactly! (But they are just feelings...I'd really love to fool around with DEQX for a while.)

Now, let me see if I can give things another spin.

If many of us accept the concept of break-in/burn-in regarding components ESPECIALLY capacitors and speakers...

...would it not then follow that, after switching polarity, a difference would more likely be caused FIRST by the disruption/change of the "broken-in" state of these components?

AND, if this could be the case, then a "reburn-in" period after a change in polarity would be needed to better gauge net differences caused by polarity itself?

We are nuts!!!  Why am I doing this! Now, where's a darn iPod when you need one!

[peakrchau]

Interesting thread! I've had some thoughts about this issue for a while that may shed some light on some of the differences we hear when running the suggested experiment.

I think the experiment is flawed basically because "another" variable is being altered called wire directionality. In case of this experiment, the directionality of wire is altered in all wires after the speaker connections in addition to changing the absolute polarity.

• On a quality system, w/ in-phase speakers: Is it audible to swap/invert the polarity of both speakers at the amp-to-speaker interface?   
  

  Please shut the theories in the drawer & lock the drawer for this voting. (Updated) Theories are not allowed in the voting process.

  
  

  .... since my system lack the polarity switch so I can't do it on the fly....
  

  ... But since we can not control how the recordings are made. The only way for us to do is to try to get it right at the playback.
  

In this computer age, most of the above points can be addressed, easily. It is possible today to alter the polarity "in the recording" using "Exact Audio Copy" or similar Editors and create a "virtual polarity switch". This program rips a .wav file than can be edited (Process Waves->Process Selection->Invert). For testing 'absolute polarity' test, create a CD-R with 10 tracks  of one song alternating between the normal and inverted polarity. You can now alter polarity by merely skipping to the next track.


DAC converters often have polarity switches but it is uncertain whether the introduce an additional inverting gain stage to accomplish it or do "it" in the digital domain. Regardless, it be interesting for the following users that hear and reported differences to repeat their experiments by using a CD-R with both polarities. I've tried it and am hard pressed to hear the difference but can easily hear a differnece if I swap both speaker leads. Conclusions?

 

• I voted YES but have to qualify my opinion:
  
  YES - in a system with Single Ended amplifier (I can hear it)
  NO - any other amplifier with distortion of less than 0.2% (I can't hear it)

  
  

  I voted yes.For me out of phase sounds bloated and not focused,especially the bass.I use SETs and when I reverse the speaker cables with CD I can hear this plain as day and night.

  ...When I changed the Theta 5a (DAC) polarity switch to 180 as opposed to the zero setting for a particular CD or selection, the change was obvious.

Last, some very interesting views by David Janszen that I thought I include a link to his page

Posted on my web site, quoted below. Comments welcome.

I will probably setup a similar POLL that flips the absolute polarity only in the digital domain but it be interesting to see what people report with this new technique.

PeAK

[jon_010101]

I voted YES but have to qualify my opinion:

YES - in a system with Single Ended amplifier (I can hear it)
NO - any other amplifier with distortion of less than 0.2% (I can't hear it)

I have a theory as to why you can hear it more easily with SET amps!  But RibbonSpeakers.net won't let me share it quite yet 

(hint -- SETs are "asymmetrical" for large signals)

[daj]

Interesting thread! I've had some thoughts about this issue for a while that may shed some light on some of the differences we hear when running the suggested experiment.

I think the experiment is flawed basically because "another" variable is being altered called wire directionality. In case of this experiment, the directionality of wire is altered in all wires after the speaker connections in addition to changing the absolute polarity.

PeAK

I hope it's okay to be frank, here. Such a thing as wire directionality may have some poetic appeal, but frankly can only be taken seriously by someone adrift in a punishingly spare vacuum of technical background.

Wooahhhh, loooook! There goes another imaginative ignoramus floating by, just outside the known Universe!

Really, any grown up should count among his/her most rudimentary knowledge that metals are uniformly conductive. Time spent thinking about such a thing as wire directionality might just as well be spent trying to turn on your stereo using only your mind.

Or am I just missing the "good chuckle" part of the Audio Circle experience?

daj

P.S. I'd like to see a new poll: To what extent should one be familiar with physical reality before one may feel comfortable theorizing publicly about it? "As much as possible" or "Who cares?"

[daj]

If many of us accept the concept of break-in/burn-in regarding components ESPECIALLY capacitors and speakers...

I'm sorry, but I have to know, are you serious?

[peakrchau]

... Such a thing as wire directionality may have some poetic appeal, but frankly can only be taken seriously by someone adrift in a punishingly spare vacuum of technical background. 

Hey Dave,
I might probably have as much as a background as you in engineering physics  at an advance graduate level and I understand the various paradigms by which we build up our knowledge....still 15 years ago, I tried following George Cardas's arrows on a 1 meter long interconnect compared to the other orientation and George's recommendation was preferred. It's been in my "stack" of Hmmms for a while and one suggestion is that a directionality/preference may be formed by the drawing of wire in a die. Have you actually tried the digital polarity test with your speakers? You're still welcome to your opinion, though.

Directionality anyone ?,
PeAK

[daj]

... Such a thing as wire directionality may have some poetic appeal, but frankly can only be taken seriously by someone adrift in a punishingly spare vacuum of technical background. 

Hey Dave,
I might probably have as much as a background as you in engineering physics  at an advance graduate level and I understand the various paradigms by which we build up our knowledge....still 15 years ago, I tried following George Cardas's arrows on a 1 meter long interconnect compared to the other orientation and George's recommendation was preferred. It's been in my "stack" of Hmmms for a while and one suggestion is that a directionality/preference may be formed by the drawing of wire in a die. Have you actually tried the digital polarity test with your speakers? You're still welcome to your opinion, though.

Directionality anyone ?,
PeAK

Various paradigms by which . . . ? Digital polarity test?  . . . was preferred? Puff puff. Squeeze metal any way you like, and while you might reorient the crystals, move the trace impurities around, and thereby change the hardness, it'll still be an electrical conductor. Not that there aren't some effects that are hard to explain to laymen, but none of the real ones is completely impossible to explain. Any attempt to claim otherwise reveals an inadequate technical background, a powerful faith in the supernatural that counteracts one's technical knowledge, or charlatan inclinations.

No matter how little basis in reality, anyone who wants to hear an imaginary effect will hear it except under controlled conditions. Get a neutral third party to help you with a double blind test on this one. Let them show the data independently. Until then, while you may call it "Hmmm", people who know about materials and physics will keep calling it an instance of audio faith.

FWIW, neither reality nor faith is an opinion.

[avahifi]

Lets think about this.  Each instrument or vocalist sends out a sound wave of some random phase angle which you (or the microphone) receives. Your distance from the performance affects where on the wave form the signals from the various performers shows up at you.  Move a few inches and the "polarity" is changed. Add to that the random scramble all the recording devices do.

I doubt very much that there is such a thing as "absolute polarity" in the playback system.  The best we can do in designing playback equipment is to not screw up the recorded polarity. That scramble of wave forms on the recording contain the "where" information about the performance (and more of course).  We want you to hear what the microphones did, and not screw up phase angles and information in your playback system.

Confused? Well me too somewhat.

Frank Van Alstine

[peakrchau]

Have you actually tried the digital polarity test with your speakers?

Various paradigms by which......etc...etc...etc.. . . . . . keep calling it an instance of audio faith.

FWIW, neither reality nor faith is an opinion.

 From your post, we conclude:

• You think George Cardas's directionality concerns are those of a charlattan 
• Short answer to trying digital polarity test  is "no"

[daj]

Move a few inches and the "polarity" is changed.

Actually, the situation is a little different from that. Moving a few inches changes the delay, and this only changes the sense of position.

Although delay does affect the phase, it affects the phase of each frequency differently. Flipping the phase by 180 degrees affects the phase of each frequency by the same amount. It causes a half cycle delay, and the period of a half cycle is proportional to frequency.

Since the sense of position is all about delay, changing the phase in a way that is not like the effect of delay might cause funny things to happen to the sense of position. There may be no effect in mono, other than possibly a reduction in how convincing the repoduction seems, but I'd almost bet that the positions of instruments in the stereo illusion would be affected.

[daj]

Have you actually tried the digital polarity test with your speakers?

Various paradigms by which......etc...etc...etc.. . . . . . keep calling it an instance of audio faith.

FWIW, neither reality nor faith is an opinion.

 From your post, we conclude:

• You think George Cardas's directionality concerns are those of a charlattan 
• Short answer to trying digital polarity test  is "no"

By "concerns", it sounds like you mean to imply that he has taken on the mantle of watching out for us somehow.

Anyway, I made no particular accusation. To include all the possibilities I can think of at the moment, one or more of: A romantic nature, inadequate technical background, pranksterism, self-aggrandizement, belief in the supernatural, boredom, imaginative habits of mind, or charlatanism.

Obviously, the romantic side of audio is nice, and none of the above possibilities is harmful to others until money changes hands, or one who espouses an erroneous belief thereby degrades someone else's appreciation of factual reality.

Here are the real concerns:

1) Belief in false technical claims exposes the believers to exploitation. When spending time and money on products that have a strong romantic component and also involve complex technologies, the average person bears the difficult burden of remaining skeptical or runs a high risk of getting ripped off. Once ripped off, no one wants to go from being a proud and happy customer to an embarrassed and angry victim by admitting what has happened, not that the facts are likely to become more obvious at some later date. That believer becomes a "client" of the charlatan.

2) The believer can become dangerous, in that a rabble of similarly inclined believers can have the collective effect of discrediting legitimate claims and diminishing the power of factual reality.

When I was once lamenting the situation to someone I know well, who is demonstrably not averse to selling various types of non-audio BS, that person advised me that there is no harm in selling things like $5000 audio cables, even if the sale includes surreptitiously jiggering the audio level up a notch to fake its superiority in A/B comparisons. His point was that the customer will get home and love his new cables because he proud to be among the few who can hear the difference and has the money to obtain such expensive cables, and if it makes that person feel smart and proud and happy, then that person has got a valuable benefit.