Polarity

than in absolute polarity (aka absolute phase) makes the sound brighter, harsher, more congested, less 3-dimensional sounding, and in general less musically and emotionally involving.  It also makes the evaluation of the fidelity and musicality of media and components more difficult, and could be one of the main reasons that analog media, which is mostly in polarity, is judged by many music-loving audiophiles to be musically superior to digital media**. How to play most if not all digital media in absolute polarity is explained.  Summing up in music-lover terms, 100% of listeners whose systems play CDs in absolute polarity when the polarity of the CDs are the same as the polarity of the CD player (the system’s net analog polarity is non-inverting) are hearing their CDs play inverted approximately 92% of the time and therefore aren’t able to enjoy the maximum potential emotional involvement with the music they love.  Due to the on going nature of the research, you may check for the date of the latest revision to this monograph about polarity.  High-Res discs and downloads aren’t exempt from polarity problems, but because I haven’t  tested a sufficiently large sample, I don’t know what percentage are inverted.

Asleep at the Polarity Switch, a Conspiracy of Negligence and Hubris, and How the Entire Music Industry Killed the Music 30 Years Ago

The first time I realized the importance of listening in absolute polarity was in 1989 when I read about it in Clark Johnsen’s seminal book The Wood Effect.  From that point forward my approach to high fidelity was changed forever, and much to my greater listening pleasure I might add.  Clark clearly makes the case that comparing components or media with different relative polarities is a fool’s errand that could only lead one’s judgments astray both fidelity-wise and musically.

Just in case my description of the problem of how music is being played inverted is too dense and wordy, here’s the bottom line.  I believe, and many other music-loving audiophiles now agree with me, that when a CD’s music meets your ear, approximately 85%* of the time it’s going to sound like it’s inverted and probably is being played inverted.  This could be a major source of errors in the evaluations of media and equipment as well as result in a tremendous loss of fidelity and musicality which drastically reduces a listener’s ability to make the closest possible emotional connection to the music they love. It almost goes without saying that the inverted playback of CDs greatly disadvantages them musically when compared to the non-inverted playback of their vinyl record counterparts.  It should be noted that the polarity integrity of each element in the chain of a vinyl record’s recording through its playback can be determined without ever listening to it in a manner similar to that described below for digital media, but is much easier to accomplish for vinyl records than for CDs, because a record’s musical content is laid down continuously in its groove, which is fundamentally different from the discontinuous way the digital representation of a CD’s musical content is laid down in its track.  Could this be a major reason why many listeners prefer analog to digital?**  Sometimes there are additional reasons, that although substantially less significant, might influence some listener’s preference of vinyl records over digital media that you may read about below.*

I’ll elaborate further on acoustic polarity, but first I think this analogy might be illustrative for some readers.  You write a doctoral dissertation on a computer and save it to a CD-R that you take to Office Depot and have them print copies to be hard bound for your committee.  Office Depot does the printing and sends the copies to a bookbindery for binding and forwarding to your committee. When you appear in front of the committee to defend your dissertation you and they see white text on black pages.  And although neither the text nor meaning of your dissertation has changed, now it’s surely a lot more difficult to read than if the text had been printed in the traditional black on white pages.

The common wisdom of the high-end audio community (that I hope this piece helps to change) is that the recording and music industry generally doesn’t pay much attention to polarity, and therefore, the polarity of media is pretty much distributed 50-50 between absolute polarity and inverted polarity.  The reason is thought to be because polarity inconsistencies can occur anywhere from the microphones (note microphone placement and reflected sound only results in phase differences at and between microphones but not their polarity) to the mixing boards, or from the mastering consoles to the final stamping of CDs, etc.  Consider the additional facts that the polarity of a given company’s media remains remarkably consistent over the years, although it’s quite likely that those same companies would have made numerous personnel, component, and stamping plant changes that we’d expect to be random.  But if the polarity distribution is closer to 92-8 (or 8-92) which way we don’t know for certain yet), then something more than random polarity mistakes must be the cause**. Therefore, it’s a statistical certainty that fundamentally nonrandom mistakes are made by a very high proportion of the recording and music industry.  The polarity of Verve and Impulse! CD labels are an example of the music industry’s confusion about polarity.  Two Diana Krall tracks on the Impulse! CD Love Scenes, Diana Krall CD are in the opposite relative polarity to the same two Diana Krall tracks on the Verve CD The Very Best of Diana Krall as determined by both subjective evaluation (listening) and objectively by comparing their waveforms with the Audacity Audio Editing Program on a MacBook Pro.  If live microphone feeds of Diana Krall are recorded to a storage oscilloscope and compared to the Impulse! and Verve CDs of Diana Krall also recorded to the same storage oscilloscope, the tracks that match the polarity of the live microphone feeds were played in absolute polarity.  And in fact some Verve CDs are in the opposite relative polarity to other Verve CDs and the same relative polarity as the Impluse! CD just referred to. I believe the Impulse! Love Scenes CD was issued in 1997 before Impulse! became part of the Verve Music Group in 1998.  

I have two original CDs under the Justice Records label that's in Austin, TX with the title: Strike a Deep Chord Blues Guitars for the Homeless  that are compilations with track #1 in one polarity and tracks 2 through 10 in the opposite relative polarity to track #1 but that's not unusual for compilations of cuts from different labels.  Both CD boxes, booklets, and jewel cases have all the same information. The information on their matrix states that they're made in the USA and both have the same matrix legend: JR 0003 01! but all their tracks are in the opposite relative polarity.  If nothing else, this finding surely makes a good argument for having a polarity switches on all digital components and once and for all sorting out the 30 plus years of confusion about the polarity of digital media and equipment!

There’s an appalling number of manufactures whose components are inverting who don’t inform their customers because either they aren’t aware of their mistakes or simply choose to ignore them and hope no one notices.  The list of components that invert but aren’t marked as such includes, CD players, DACs, speakers, headphones, and practically anything else I can name, including components with polarity switches and switchable polarity inverters that indicate the opposite polarity setting to their true polarity. 

It’s now become relatively common for reviewers to report the polarity of components they evaluate and sometimes even the electrical connections/acoustic polarities of a speaker’s individual drivers, yet I can’t remember a single instance where they’ve mentioned the polarity of the media they used for their evaluations; however, the polarity of the media has exactly the same affect on the fidelity and musicality, or lack thereof, as the polarity of the components, because they both need to be correct or both incorrect in order to sound correct. The reason I think it’s negligence and hubris in the music industry is because if either the producers of the media or the producers of the components listened to the way their media and components sound together, they should have known that there’s something rotten in the pits.  The bottom line is that most of the makers of digital media and playback components aren’t on the same digital page, and until they are, it’s a sonic and musical polarity crap shoot for those music-loving audiophiles who want to experience the greatest possible emotional involvement with the music they love.

I relish the idea that subjective evaluations of fidelity and musicality will be shown on many occasions to be vastly superior to objective evaluations.  Only sound with compressions that differ from its rarefactions (asymmetrical) has audible polarity, because changing the polarity of identical (symmetrical) compressions and rarefactions doesn’t really change anything, so there’s nothing different to hear in the same way that’s there’s nothing different to see in the mirror image of a symmetrical object.  

There are 'experts' who argue that because we listen to live music at various distances from its sound sources that  polarity doesn't matter and isn't and therefore isn't audible when recorded and played back, but that analysis is fundamentally flawed because the distance a listener is from to a sound source has no bearing on its polarity because the polarity of the leading pressure or rarefaction of the sound source’s sound wave’s wave fronts are the same when it first reaches the listener's ears as when it left the sound source.  And the polarity of reflected sound doesn’t change.  Most people I know can easily hear the difference between absolute polarity and inverted polarity of reproduced music in double-blind testing when the speakers or headphones used are phase coherent and they invariably prefer non-inverted to inverted polarity.

For more about polarity click on Polarity Think Piece:  A Speculation Regarding Perception of Detail or http://audiogeorge.com/polarity-think-piece-a-speculation-regarding-perception-of-detail/ to read a think piece about polarity.  I believe that anything we hear should ultimately be measurable; unfortunately we haven’t learned how to measure everything we hear.

It now appears, after I’ve determined the polarity of over 3,500 CDs from hundreds of CD labels, that 80 to 90% of CDs (my best estimate is approximately 85% when the polarity of the CD player isn’t known, but approximately 92% of CDs play inverted on 92% of CD players, please see the New Polarity Math* at the end of this paper) are being played back inverted on CD players and on digital to analog converters (DACs) that are ostensibly non-inverting including those with polarity switches.  And at least so far, what I’ve heard is, that except for test CDs and samplers with tracks from more than one label, all tracks on a single CD have the same relative polarity. The good news here is that once you’ve determined the polarity of any track, you can set it and forget it, and I call that the Absolute Reality of Absolute Polarity.  It’s a bit complicated to sort out, but it appears most players and DACs frequently have an even number of inverting gain stages (and are supposed to be non-inverting) after their internal DACs, because most DACs have an I/V stage (current to voltage) on the DAC itself which inverts the analog signal which if overlooked could cause a mistake.  However, that’s only one of many possibilities as to how Analog to digital converters (ADCs), CD players, and DACs might be unintentionally inverting.  In fact it could be something as simple as using the inverting input of an ADC converter(s) when recording the original performance or copying an analog recording and then not taking that into account when making the glass master. On the other hand, perhaps there’s a polarity flag for that’s being changed, but I’m not knowledgable enough about the CD redbook standards to answer that question.  It’s not as simple as just knowing what the playback polarity is by listening, because how polarity is realized and heard can be the result of an inverted CD disc and inverting playback that’s net non-inverted or any of the three other combinations e.g. the CD isn’t inverted and its playback is non-inverting, that’s (non-inverted), a CD that’s not inverted but it is played back inverted (net inverted), and an inverted CD with non-inverted playback (net inverted).  This is one of those rare cases where two wrongs really do make a right.  It also seems to me all standalone consumer and professional CD duplicators I’ve heard produce copies that are inverted relative to the copied discs, and that could be a major reason why many people think copies tend to sound better than original CDs.  Computer made copies aren’t supposed to be inverted unless the operator selects that option, but I don’t know if that’s always the case.

The polarity of discs made from a glass master standard test disc can’t be verified electronically until the glass master or a CD made from the glass master has been independently verified optically/physically. In order to definitively determine if a CD player is inverting, we need to make a glass master with asymmetrical test signals that are embedded in a music track to include meta data for the music track that might affect polarity and is checked with a very high powered optical or a scanning electron microscope to verify that its pits and lands conform to the CD Red Book standard.  When the glass master or a CD made from it isn’t optically verified to be correct, then just as above with CDs and CD players, there are two unknowns when checking its polarity electrically.  In which case two wrongs and two rights will make the glass master and CD made from it appear correct while a single wrong (either the player or the glass master or a CD made from it is inverted) will make the glass master and CD made from it appear inverted. However, their may be a stage in a CD player or transport where we could read and compare the bits of the raw data, (the raw data in itself has no polarity until it’s processed), we burned to a test CD, with the bits of the raw input data.  In that case we wouldn’t need an optically or electron scanning microscope verified glass master or CD made from the stamper made from the glass master to create a standard test CD.  Thus,ultimately, it can be determined to a 100% scientific certainty whether it’s approximately 92% of the CDs that are made inverted or approximately 92% of CD players that play inverted.

We can compare the relative polarity of a standalone CD or computer copies to the copied discs to find out if they invert copies. But for the same reasons, as for CD players, we can’t know whether the polarity of a copy made from the input of an external source to a standalone or CD copier is inverted relative to the copied disc, unless we know the output polarity of the input component.

To test the relative polarity of the inputs to the outputs of standalone DACs and CD players’ digital outputs, we need a reference standard standalone DAC (RSD) of known polarity. We can create an RSD by injecting a properly configured test signal into the DAC’s digital input.  Then we test the DAC’s analog output for agreement with the Red Book standard, and if it agrees we have our RSD. We can’t know if a CD transport’s or CD player’s digital output is inverted relative to its analog output without an RSD. Because as above, when testing CD players and DAC’s of unknown polarity, there are obviously are two unknown variables.  Regardless of the polarity of the CD media, the CD player or the DAC being tested, when we use the RSD there’s only one unknown, so we’ll know the relative polarity of the tested component’s digital and analog outputs relative to the analog output of the RSD. However, the testing of transports requires a CD of known polarity because the transport’s digital output polarity is unknown and even using an RSD only makes the combination of CD transport and DAC effectively into a CD player, and again as above, with a CD player it requires a CD of known polarity to establish its polarity.

Unlike the polarity of a vinyl record groove that’s relatively easy to verify optically, the digital information imprinted in the spiral track of a glass master isn’t laid down in a continuous pattern because of the Reed-Solomon cross-interleaved error correcting code used to make the disc’s playback less subject to errors caused by physical damage or contamination to the disc.  We can know what the pits and lands should look like because the Red Book standard explicitly defines their pattern on a glass master and a CD made from the stamper made from the glass master so they can be verified optically.  Since the digital signal’s 1′s are represented by the pit edges and the pits (the pits are bumps to the laser because CDs are stamped on their label side) and the continuous surface of the pits and lands between the pits are represent the digital 0′s, only the transitions from pit to land and land to pit are the digital 1′s. So even if the stamper’s pits were somehow made physically reversed (convex instead of concave) it wouldn’t affect the polarity of the CD stamped from that disc.  I don’t know if there’s a digital polarity flag in the CD Red Book standard, but I’m sure an engineer who’s familiar with the CD Red Book standard could help us find out why so many CDs are made inverted.  CD-Rs and CD-RWs have no pits and lands, because it’s only transitions between areas of greater and lesser reflectivity that defines the digital 1′s so they’ll still work perfectly.

How is it that approximately 8% of CDs are played back inverted on those same CD players mentioned above?  Are they the CDs that are made inverted, or could they really be the non-inverted CDs, if it turns out that those same CD players and DACs that are supposed to be non-inverting, are actually doing the inverting?  We should find out the reason that hi-res online downloads may also be sometimes inverted.  I don’t have the technical expertise to make the relatively easy technical tests that would once and for all get everyone on the same digital page.  I hope we could work together to hear a second coming of CDs and digital in general.  Let’s try to solve the problem of inverted playback polarity that just might be the biggest mistake in the history of audio.

I believe for the last 30 years of digital technology, incorrect polarity has caused more grief for music-lovers and musicians than anything else I know of.  In my opinion the effect of absolute polarity on musicality easily trumps jitter reduction and all the “tricked out fancy” filters touted by the high-end component companies.  Whatever the ultimate causes of the huge disconnect between the makers of CD media and makers of CD players, because the emperors of audio have no ears/are afraid of how they’ll be judged when the polarity truth is finally the norm.  30 years of approximately 85% of CDs being played inverted has lead to mistaken reviews, unnecessary equipment “upgrades”, and unneeded tweaks, resulting in a loss of musicality that shouldn’t be acceptable to any composer, musician, or music-lover.  And when the audio and music industry gets absolute polarity right, they won’t just be improving one audio system at a time, they’ll be improving everyone’s audio systems all at once.  

*Here are some additional reasons that although not nearly as important as the polarity differences between most digital and analog media described above, sometimes makes comparisons of their sonic and musical differences more difficult than one might have thought. Some phono cartridges have more high frequency phase shift that frequency-specific delays the arrival of its high frequencies more than digital media. That tends to favor speakers with less than optimal time-alignment because their tweeters are mounded flush with its other drivers on a vertical baffle that’s perpendicular to the floor and results the speaker’s high frequencies arriving at the listener’s ears ahead of its midrange frequencies and comb filters with the speaker’s midrange and isn’t faithful to the phase response of the original performance.

Another reason is that recordings made with a Blumlein microphone technique that uses a coincident pair of crossed-figure-8 microphones (BLM) have out of phase high frequency crosstalk that puts the hall ambience/audience sounds into the opposite channel and out of phase. Many phono cartridges may actually make vinyl records that were made with BLM sound closer to the original performances than the original analog, 16-bit, or high resolution digital masters because their mechanical high frequency left to right and right to left channel crosstalk that’s out of phase may actually cancel some of the effects of BLM and thus be more faithful to the original performance. At one time I owned a Denon PCC-1000 stereo phono cartridge crosstalk canceller that was meant to heighten stereo imaging by compensating for the mechanical crosstalk of phono cartridges and thereby restore the original stereo imaging. It worked as advertised but unfortunately increased the noise due to less summed channel noise cancellation, so ultimately I didn’t like the tradeoffs.

*The New Polarity Math (NPM)

My beta testers and I have listened to hundreds if not thousands of audio systems whose polarity we didn’t know in advance.  Included among those systems were those at both The Consumer Electronics Show (CES) and The Home Entertainment Show (T.H.E.) at Las Vegas in January 2009.  Our empirical observations were that approximately 85% of the time the CDs they played sounded inverted.  There’s only two ways that a CD can be played inverted on an audio system whose components are connected to be in absolute polarity, first, an inverted CD is played by a non-inverting CD player, and second, a non-inverted CD is played by an inverting CD player.  Thus music-loving audiophiles try to wrap your ears around The New Polarity Math that dictates that if you don’t have any information about the polarity of a CD or a CD player, then the highest percentage that both the CDs and CD players can both be inverted and non inverted is either approximately 92% of CDs inverted and approximately 92% of CD players that aren’t inverted or the reverse, that 92% of CDs that aren’t inverted and 92% of the CD players are inverted, for the random result that CDs will be played inverted approximately 85% of the time.  And if the polarity of the CD player is known and the playback system is set to play inverted, then CDs chosen at random would play in polarity approximately 92% of the time.  But having said that, there are other possibilities for the percentages of CDs or CD players to be inverted, but since both CDs and CD player exhibit both polarities, whether it’s the CDs that are inverted or the CD players that are inverted, whichever is inverted must be inverted more than 85% of the time and the other must be non-inverted more than 85% of the time.  Therefore, until it’s definitively established whether it’s the CDs or the CD players that are inverted, an inverting if one doesn’t have an easy way of changing polarity then if the amplifier to speaker wire connections (preferably at the speaker end) are set to the way that most CDs play in absolute polarity, then more than 85% and possibly as much as 92% of randomly chosen CDs will be played in absolute polarity.  For the sake of the music manufactures of media and components may contact me for pro bono consultation regarding polarity etc.

If Eo = the empirically observed fraction of CDs that are played back inverted, CpN = the fraction of CD players that aren’t inverted, and CDi = the fraction of CDs that are inverted, then CDi = (Eo + CpN – 1)/(2CpN -1) and of course if instead of CpN you substitute CDn = the fraction of CDs that aren’t inverted, then the fraction of CD players that are inverted that we call CpI = (Eo + CDn – 1)/(2CDn – 1).

**Why the Polarity Mistakes Can’t be Random

If P equals the fraction of A to D converters or other equipment in the digital recording/playback chain that isn’t inverting, then 1 – P equals the fraction of  that equipment that is inverting.  If the makers of CDs or playback equipment randomly (half the time 50% = .5) made polarity mistakes, the fraction of digital recordings whose playback would be inverted equals .5 x P + .5 x (1-P) = .5 P + .5 -.5P = .5 (50%), but in fact it’s approximately 92% of CDs that playback inverted on approximately 92% of CD players.  Therefore, polarity mistakes by the makers of A to D converters, CDs, CD players, and DACs can’t be random because the random result of .5 is independent of the value of P.  Thus if you randomly set a CD system’s playback polarity (50-50), the system will playback 50% of CDs in polarity, but as explained above in The New Polarity Math, approximately 92% of CDs playback inverted on approximately  92% of  CD players, so when in doubt, invert polarity because that will give you the highest probability (92%) of playing back in absolute polarity.

Some recording engineers and audio experts suggest that the polarity problem can be the result of random microphones being plugged/mixing board polarity switches being respectively plugged in/set wrong.  But for microphones or mixing board switches to be the cause of an entire CD to be inverted, all the microphones' polarity/polarity switches must be net inverting since on a given track each feed is almost always in the same playback polarity.  And that's further reinforced by the fact that any given CD label's original compact discs always play in the same polarity on a given playback component whereas if the microphones and polarity switches being randomly set inverted, then some of the company's CD would play in opposite relative polarities.

 A Conundrum, Real World Empirical Test Results, Email Between Myself and Emotiva Audio Corporation, and Email Between Myself and Oppo Digital

Conundrum:  When John Atkinson technical tests of the first edition of the Cary Audio Design 303T Classic CD Professional SACD Player that accompanied the review by Michael Fremer in September 27, 2010 issue of  Stereophile, his tests found it to be inverting (Cary Audio Design has assured me that they’ve made a firmware upgrade for the player that makes it non-inverting) at its both its single-end RCA and balance XLR outputs.  I presume that he played a polarity test disc and observed a negative going signal(s) on an oscilloscope.  The oscilloscope picture of the Oppo BDP’s polarity test show a positive going signal on both channels, and Oppo Digital insists that the BDP-95, BDP-105, and  BDP-105D aren't inverting, yet it output is in the same relative polarity as the original “first edition” inverting Cary Audio Design 303T player!  This is an example of the how confused polarity testing can be and the reason it needs to be nailed down once and for all in order that music-loving audiophiles may enjoy the greatest possible emotional involvement with the music they love.

In my opinion, another example of confusion about polarity is the Musical Fidelity X10-D Tube Buffer with its single tube that alleged purpose is for its high impedance input and a low impedance output to make a better impedance match between a digital source and analog component that it's connected between such as a CD player's or DAC's digital output and a preamplifier's analog input is really improving the sound of most digital playback because it's inverting not because of its impedance matching properties.  And another component that's received excellent reviews but in my opinion plays approximately 92% of all tracks on approximately 92% of all CD in polarity is the Electrocompaniet EC 4.8, that seems to be based on a DVD player.  It seems again that reviews hearing polarity but don't realize that's what they're preferring.

Email on March 20, 2012 between Emotiva Audio Corporation Customer Service and myself regarding the output polarity of their Emotiva  ERC-2 CD Player  

Dear Nick Kaumeyer,

First of all the inversion may be occurring in the digital domain. Secondly, music mostly consists of asymmetrical sound waves and there’s plenty of scientific research that has established that because listener’s neurons may not fire on one of the polarities at certain frequencies that many listeners can discern whether the playback polarity of music matches the music’s original polarity.  In his Follow-Up comments referred to below, John Atkinson states, “…Both outputs inverted absolute polarity-another factor that will influence comparisons if not taken into account…”, so it appears that both John Atkinson and I disagree with you.  It’s obvious that you didn’t read any of the material at the first two links in the penultimate email I sent you.  If and when you find the time to read the first two monographs, please let me know your “let the bits fall where they may critique.”