[Stu Pitt]

Hifisoundguy is pretty crazy, but he's onto something here...

I've had this demonstrated to me by a dealer.  I was demoing a pair of Revel Concerta towers.  I thought they sounded too distant (soundstage was far behind the speakers), and the bass was overwhelming.  When he switched the polarity at the speaker end, the soundstage came far closer, and the bass calmed down.  Everything snapped into far better focus.  Even after this they weren't the speaker for me, but it opened my eyes a little bit.

According to him, in essence its like having a phase reverse switch.  I've heard elsewhere that some speakers are wired 180 degrees out of phase.  Maybe they are too?  I don't know the technical end of XOs or stuff like that, so take it as you will.

I've tried it on several speakers.  Some sounded better, some sounded worse, and some sounded the same.  I think it depends on the speakers and possibly the recording too?  I don't know.  The only thing I truly know is that my Audio Physics sound better the traditional way.

On a side note, I read in a review (can't remember which one) that when Santana's debut album was originally released it was out of phase and the channels were the opposite.  When MoFi remastered it, they corrected it.  Maybe that's part of why it sounds a lot better?

[opaqueice]

According to him, in essence its like having a phase reverse switch.  I've heard elsewhere that some speakers are wired 180 degrees out of phase.  Maybe they are too?  I don't know the technical end of XOs or stuff like that, so take it as you will.

Many - perhaps most - speakers have one of the drivers wired out of phase with the others.  Depending on the type of crossover and the driver arrangement this is necessary to prevent phase cancellations.  So for such speakers there is nothing you can do to have the "correct" absolute phase, if that even meant anything (which it doesn't).

It's also worth bearing in mind that many instruments have an "absolute phase" that varies with angle.  If I hit a gong I push it in, which means the leading edge of the wave coming off the side I hit is low pressure.  But on the other side of the gong it moves out, so the leading edge is high pressure.  So depending on where you (or the microphone) are located, you'll hear a different "absolute phase".  When you mix a recording using channels recorded from mics at several different locations, you obscure this even more.

The only kind of recording for which absolute phase might make some sense in a binaural one (two mics situated on either side of a dummy head where the ears should be), listened to over headphones.  Such recordings have a truly eerie soundstage - far, far better than anything I've ever heard from stereo speakers.  Approximately 0% of "audiophiles" listen to music that way .

Try this for example:  http://www.youtube.com/user/LovelyVirus

[DustyC]

Stereophile has a test CD with 2 tracks where the only difference is the absolute phase. Very noticeable difference between the 2 tracks . I've played around with phasing in my system. Recordings that are simple miked affairs make for best source material. VITAL records (recorded by David Manley) are good ones. If either your power amp or preamp has an odd number of gain stages you'll have to reverse the speaker leads to maintain phase. The effect is almost impossible to gauge with most multimiked recordings. It's one of those things, that once you learn to listen for it, will either drive you crazy or easily be forgotten if you don't care.
VTA adjustment for each record anyone?? (yeah, adjusting for absolute phase is like that).

[HiFiSoundGuy]

  Your have to find out what sounds best with your system....reverse the cables at the amp or at the speakers.....

[clarkjohnsen]

I was just alerted to this discussion about my little red book, The Wood Effect: Unaccounted Contributor to Error and Confusion in Acoustics and Audio

And still there is much confusion, even right in this thread. But let's start with a definition. The abstract to The Wood Effect says it best:

"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."

The argument has been made that, well, with all those different mics and channels, what hope is there for getting a single polarity on any recording? Those would of course be pop recordings; go to the classics, or to jazz, or to folk -- music that's generally performed live and not created in the studio -- and you'll find plenty of relatively simple, two-mic (or close to it) recordings on which polarity is totally audible.

But still there's the loudspeaker hurdle; 90% of 'em have phase-gemischt crossovers and all hope is lost, with everything sounding so-so.

And for those reasons we see people disparaging the very concept of an Absolute Polarity. If they can't hear it... well, it must be B.S.

A few copies of this pretty good book (John Atkinson: "Fascinating... a tour de force...") are still available from the author for $20 plus shipping. Meanwhile one may learn something from this column of a few years back:

http://www.positive-feedback.com/Issue1/cjwoodeffect.htm

Cheers to ears!

clark

[PMAT]

Here is an easy way to check phase which I use when switching components. The first track on Roger Water's AMUSED TO DEATH CD starts with the sound of crickets and then the sound of dogs barking way to the right. The dogs really sound like they are outside your house next door. If you have a phase problem the dogs won't be there. I recently bought a Conrad Johnson preamp and amp and the dogs were in front. I flipped the ac plug on the preamp and the dogs appeared far right. Everything in the image sharpened and the stage became normal. The recording technique used on this album uses phase manipulation to fool your brain into hearing things way outside your speakers. If you get your system to do this CD right, the rest of your collection will sound better! 

[Wayner]

So Conrad Johnson doesn't use polarized plugs? Or, you just made your chassis connected to the "hot" side of the AC. So much for UL approvals, huh.

Wayner

[Russell Dawkins]

Here is an easy way to check phase which I use when switching components. The first track on Roger Water's AMUSED TO DEATH CD starts with the sound of crickets and then the sound of dogs barking way to the right. The dogs really sound like they are outside your house next door. If you have a phase problem the dogs won't be there. I recently bought a Conrad Johnson preamp and amp and the dogs were in front. I flipped the ac plug on the preamp and the dogs appeared far right. Everything in the image sharpened and the stage became normal. The recording technique used on this album uses phase manipulation to fool your brain into hearing things way outside your speakers. If you get your system to do this CD right, the rest of your collection will sound better! 

... and yet, this has nothing to do with absolute polarity. Absolute polarity, i.e., whether the speaker provides a compression or rarifaction in response to any given part of the musical signal, would not be affected by reversing the AC power plug.

[PMAT]

The plug is not polarized (old style) but only on the pre. The amp has a polarized plug. Are you saying it's dangerous?

[Russell Dawkins]

No. I'm saying that reversing it has no effect on what is under discussion here - absolute polarity.

[andyr]

So Conrad Johnson doesn't use polarized plugs? Or, you just made your chassis connected to the "hot" side of the AC. So much for UL approvals, huh.

Wayner

Wayner,

You seem to have difficulty grasping the two simple concepts which have been laid out here.  So let me try and give you "Polarity 101"!    Print off this thread, crack open a long-neck, sit back in your favourite armchair, put your music on and think about what you're reading!  

Let's deal with the last one first - the "polarity" of the mains connection.  Clark in his book makes the point that if this is not optimal to start with, trying to hear "correct absolute polarity" is much harder.

Yes, a mains circuit has 'active' and 'neutral' and the fuse should be on the active side ... so flipping a US-style mains plug so that suddenly the fuse is now connected to the neutral side is not a good idea!  However, most other countries typically have 3-pin plugs - so this is not possible.

The basis of Clark's recommendation is to do with which end of the power transformer primary winding is connected to active and which is connected to neutral.  The sound which your amplifier produces will be different (better!) if the primary winding is connected one way round, than the other.  I believe it is due to 'parasitic capacitance' in this winding (whatever the hell that is!   ).

Most manufacturers don't take the time to make sure they are connecting the power transformer "the right way round" - hence consumers need to.  Otherwise you are listening suboptimally.  If components came with a DPDT mains switch (with the fuse between the switch and the IEC socket) whereby you could reverse the connections going to the powertran with this switch (the powertran was on the central tags of the DPDT switch), this would be a simple thing to do.

There's a seminal "BoundforSound" article about how to measure the earth voltage on your (metal) case and determine whether the powertran has been connected right.  I believe in it - which is why I make sure my powertrans are connected optimally.  

OK, now "absolute polarity".  Someone has already made the point about a singer and a microphone diagram ... but then some smart-alec chipped in with a comment about which side of the microphone you happen to be on!  

So let's ignore microphones - you're in a room with some live singers & musicians.  As the trumpet player sounds, you hear the leading edge of the wavefront hit your eardrums.  And it sounds like a trumpet.  If you recorded it with correct absolute polarity and played it back in front of you through a one-driver, "full-range" speaker, it would still sound like a trumpet.

But if you then flicked a phase reversal switch on the tape/CD-R machine, so that the recording was now playing back at you with reverse absolute polarity, it would sound different - strange in fact.  This is because you are no longer hearing the true leading edge of the notes.

Likewise if a triangle player (live) strikes a note, you will hear it directly.  If this note was recorded and played back with reverse absolute phase, it would sound different.

In terms of hifi systems, absolute phase is not the same as relative phase.  Let's, again, take the simplest scenario of a stereo system with single-driver full-range speakers (because some people get themselves hopelessly twisted up when they contemplate individual drivers in a multi-way speaker being connected up reverse).  You have to have both channels connected in the same way, to get a strong central image.  Otherwise the sound will come from a diffuse area which is spread all over the front of the room.  If they are connected correctly then you have your speakers in correct relative phase/polarity.

With these single-driver full-range speakers, you can have the speaker wires connected thus:
L: red to '+' / black to '-'
R: red to '+' / black to '-'
or
L: red to '-' / black to '+'
R: red to '-' / black to '+'.

Assuming your system doesn't invert polarity all the way along the chain (and some components do - it basically depends on how many gain stages they contain), the first option above delivers correct absolute phase.

And what does this deliver to you?  If you are listening to a CD where the recording engineer took the trouble to ensure it was recorded in correct absolute polarity ... then you will hear it optimally.  If it was recorded badly (in reverse absolute phase) then you'll hear it in reverse polarity.  And if - like many recordings - some mics are connected up the correct way and some are reversed - then it won't matter how you flip the phase switch (or change the speaker connections) ... you've got a mish-mash.  

As this is "the real world" - in terms of recordings - it's pointless jumping up and down to flip speaker cables every time you listen to something.  But if you have a convenient "phase reversal switch", you may as well use it.  

If you say you can't hear absolute phase change then IMO there are two possibilities:

1.  you have speakers which use higher-order crossovers which require one driver to be connected in reverse ... this makes it very difficult to pick up absolute polarity issues.  (Mine are like that.   )

2.  you are one of those people who are not particularly sensitive to it (which is perhaps a blessing!   ).

Regards,

Andy

[Brown]

Well said Andy. As one who is sensitive to correct polarity, it makes a big difference for me. Couldn't live without that switch. Mine is in the digital domain. no invert switch on preamp. The phono stage has one as well. I have found that LPs are the worst culprits. Some with the bass out of phase some just all out of phase. Love that switch.

[clarkjohnsen]

Here is an easy way to check phase which I use when switching components. The first track on Roger Water's AMUSED TO DEATH CD starts with the sound of crickets and then the sound of dogs barking way to the right. The dogs really sound like they are outside your house next door. If you have a phase problem the dogs won't be there.

OK, so far so good. That sort of thing can easily happen.

I recently bought a Conrad Johnson preamp and amp and the dogs were in front. I flipped the ac plug on the preamp and the dogs appeared far right. Everything in the image sharpened and the stage became normal. The recording technique used on this album uses phase manipulation to fool your brain into hearing things way outside your speakers. If you get your system to do this CD right, the rest of your collection will sound better! 

Waitaminnit! We were talking about acoustic polarity, not AC polarity. PMAT's technique may well work for that alignment, but the result could still be wrong in the acoustic domain.  Gotta try both!

Regarding AC polarity, the enhancing quality of getting it right is best achieved when every piece of gear is set correct. How this may be done is a matter of public record, but also included in The Wood Effect.

clark

[clarkjohnsen]

So Conrad Johnson doesn't use polarized plugs? Or, you just made your chassis connected to the "hot" side of the AC. So much for UL approvals, huh.

Wayner

It's a lot more complicated than that.

But as the experiment can only be carried out by (temporarily) bypassing the physical polarization, yes, for the moment the "hot" is reversed. But if it's found that the unit is wired incorrectly fo the sound, a UL-approved-type correction can be implemented.

[clarkjohnsen]

... and yet, this has nothing to do with absolute polarity. Absolute polarity, i.e., whether the speaker provides a compression or rarifaction in response to any given part of the musical signal, would not be affected by reversing the AC power plug.

So one might think, but in fact acoustic polarity is more discoverable after all the AC plug polarities are corrected -- which, unlike the former, can be done with a meter!

[clarkjohnsen]

OMIGOSH! Andyr got it almost all right! More so than anyone else I've read, over the years, over the decades.

Congratulations! The members here are fortunate to have someone with such clear understanding and the ability to express it in few words.

I'll only take issue with this: "If you recorded it with correct absolute polarity..."

First of all, "correct" and "absolute" are redundant. The term Absolute Polarity denotes correct polarity at the ear. As for recordings, they may be in either of the two polarities, and afterwards right or wrong at your ear, willy nilly.

There is no standard that dictates one or the other on any medium.

Oh, one more thing. The word "phase" should not be used when "polarity" is meant, although many erroneously do, even myself sometimes!

[opaqueice]

"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.

That part is wrong.  It's just not true that "music creates compression waves".  First off, all sound waves consist of an alternating series of rarefactions (lower air pressure) and compressions (higher air pressure) - that's what a sound wave IS.  When the wavefront arrives at your ears/mic, the first deviation from average pressure can be either of the two.  Now probably what you mean is that the leading edge of the wave generated by a musical instrument is a compression.  But that's not correct either - vibrating objects can either create compression OR rarefaction wavefronts, depending on how you strike or pluck them and where you're standing. 

I've done the experiment myself to verify that - I took a string, plucked it, and recorded the result with a mic.  As expected, whether the leading edge of the waveform was compression or rarefaction depended on which direction I pulled the string before releasing it.  Same goes for percussion - you can flick a pen with your fingernail, strike a gong, hit a cymbal - the leading edge will be either rarefaction or compression depending on where you are standing relative to the direction the pen/gong/cymbal was struck from.  For something more complex like a violin, I suspect the leading edge will still depend to some extent on the direction of the bow stroke and the position of the listener, but I haven't tried to verify that.

If you don't believe me, with a cheap mic and a laptop you verify it yourself in five minutes.  Just record the sound of flicking a pen (or paper or probably anything else).  Do it once flicking towards the mic, and once away, and see for yourself.

[opaqueice]

So let's ignore microphones - you're in a room with some live singers & musicians.  As the trumpet player sounds, you hear the leading edge of the wavefront hit your eardrums.  And it sounds like a trumpet.  If you recorded it with correct absolute polarity and played it back in front of you through a one-driver, "full-range" speaker, it would still sound like a trumpet.

But if you then flicked a phase reversal switch on the tape/CD-R machine, so that the recording was now playing back at you with reverse absolute polarity, it would sound different - strange in fact.  This is because you are no longer hearing the true leading edge of the notes.

Actually the difference is quite subtle.  I happen to have an audiophile test CD (from Chesky Records) in which there's a recording of trumpet note and then the polarity-reversed version.  I haven't tried to ABX it, but the difference is really small even over phase-coherent headphones.

If you say you can't hear absolute phase change then IMO there are two possibilities:

1.  you have speakers which use higher-order crossovers which require one driver to be connected in reverse ... this makes it very difficult to pick up absolute polarity issues.  (Mine are like that.   )

2.  you are one of those people who are not particularly sensitive to it (which is perhaps a blessing!   ).

There is a third possibility which IMHO is far more probable.  Many audio systems induce significant distortion.  If the distortion is asymmetric with respect to zero voltage - which is usually the case - reversing the polarity will make an audible difference on any recording which is itself asymmetric (and that's almost everything other than pure single test tones).  So my hypothesis is that people that hear clear differences are listening through systems that induce lots of harmonic distortion, hence making the effect clearly audible.  If instead you listen through a low-distortion system, the effect is extremely subtle (generally it's audible only under artificial circumstances).

[andyr]

Well said Andy. As one who is sensitive to correct polarity, it makes a big difference for me. Couldn't live without that switch. Mine is in the digital domain. no invert switch on preamp. The phono stage has one as well. I have found that LPs are the worst culprits. Some with the bass out of phase some just all out of phase. Love that switch.

I'd be interested to know what speakers you have, given you find the polarity reversal switch to be useful?

I'm thinking they must use 1st order Xovers?

Regards,

Andy

[andyr]

OMIGOSH! Andyr got it almost all right! More so than anyone else I've read, over the years, over the decades.

Well thank you, Clark.  You see ... it was worth you spending the effort a decade ago to email me answers to all my Qs, after I had bought "The Wood Effect"! 

And, yes - sorry - I should have left off "correct".

Regards,

Andy