Absolute polarity. In phase. Sometimes audiophiles get confused. Which is which? Absolute polarity means that a leading edge is heard as a positive pressure wave or compression (higher density), not a negative wave or rarefaction (lower density or decompression). The term's absolutism suggests an unalterable constant. It indeed is in nature where transients are always on the rising first portion of the wave form. For playback purposes however, it is actually merely one of two possible results or outcomes. It is not a given. Hence in that sense, it's not an absolute, guarantee or unalterable constant. It merely means that the loudspeakers (wired properly in phase with each other yet possibly in inverted polarity relative to the source) interact with a given recording such that all transients initiate with a push of the drivers, not a pull. So there's recorded polarity which is unknown since there are no codified standards; there's our system's polarity which we can control; and there's how both of them interact. Correct polarity for a playback system (which could mean inverted to compensate for inverted recorded polarity) is simply the one that, on any given recording or track, produces absolute polarity at the ear.
That's the thing to bear in mind. The only way to determine whether a transient attack is inverted by riding on a negative pressure wave is at the ear. The natural sharpness of attacks turns blunted. That's the theory. In practice, determining absolute polarity during playback gets complicated by the nonlinear phase behavior of the stereo loudspeaker pair. Depending on crossover slopes and whether all of the drivers are wired in phase (some speakers deliberately have tweeter and woofer push while the midrange pulls), speakers can introduce their own blunting and dulling of transients regardless of whether the received signal was in correct polarity or not. Then speaker setup, room size and listener distance introduce nonlinear phase rotations between direct and reflected signals to muddy the waters. Things get further complicated by the fact that most modern recordings are endlessly overdubbed, multi-mike'd, multi-tracked and heavily processed affairs often assembled of parts that were recorded in various locations. Chances for polarity reversal from track to track -- or even within a track or overlaid as opposing polarities -- are many. This results in an unpredictable and thus unknown recorded polarity.
In fact, there's a 50:50 chance that any given recording features inverted polarity. To correct those instances and enjoy absolute polarity at the ear as you would during any live acoustic event requires phase inversion somewhere in the playback chain. Preferably, this can be set on your CDP, DAC or preamp via remote phase reversal. Recorded polarity could vary from track to track or from side to side on an LP to make manual compensation less convenient. A last resort is flipping loudspeaker leads on one end but of course for both speakers. It's important to understand that the pursuit of absolute polarity -- or transient fidelity as it should be more helpfully thought of -- doesn't give a damn about whether your system, as is, inverts polarity or not. It's how recorded and system polarity add up from song to song that absolute polarity in audio is established. It can only be determined in situ, by ear - and only if the recording quality makes it transparent enough in the first place; if the speakers' own phase behavior is benign enough; and if the speakers' interactions with a given room are such as to not dilute the differences of polarity into something far too marginal to be audible or meaningful.
After all, speaker crossovers that discombobulate the different frequency components riding on a transient (fundamentals and their harmonics) by spreading them out over different drivers (which suffer crossover-induced phase shifts at certain frequencies and may be out of phase with each other) are hardly the proper tool whereby to assess absolute polarity's "blatant audibility" which its champions tirelessly and often aggressively proclaim as though not hearing it rendered you deaf. The fact is, certain speakers and setups make it a non-issue as will many recordings. Mono is said to make it easier to hear than stereo. If you can't hear it, don't sweat it. Some polarity pundits simply must get a life and come off their high horses.
|Further confusion on this topic arises from the conflict between absolute and measurable polarity such as the Smart Devices System 2000 and EZ-Phase 2 allow for. Either self-generated electrically or acoustically or via special signals recorded on a CD, these tools allow you to determine unequivocally whether your system inverts polarity or not from component to component. Sources, preamps and amplifiers all may invert polarity. Ditto for speakers. Measuring each component can determine this so that you can subsequently correct for it with the speaker cable. After all, regardless of how many inversions you may suffer, it's either in or out of polarity at the end. You need to fix it only once. If speaker phase is twinned because some drivers are in phase with the incoming signal while others are out of phase, you'd have to rewire the voice coil lead on the offending driver. Still, a measurably polarity-correct system does not guarantee that you're listening in absolute polarity. It depends on the given recording. That's a 50:50 crapshot. Overly processed and bollixed-up albums or tracks will often sound bad either way - different bad perhaps but bad nonetheless.
We're not entirely done yet. If you must correct for absolute polarity at the speaker leads rather than at the source or preamp, you're potentially changing THD in audibly significant ways. That depends on the amplifier/speaker interaction. Blame Eduardo de Lima of Audiopax for the math that explains this phenomenon to further confuse the polarity/phase issue. Connecting both your speakers out-of-phase relative to your amp can sound better than in phase. That's because just enough harmonic distortion cancellation occurs in one position -- i.e. some of the amp's THD is cancelled by being out of phase with the speaker's innate distortion -- that it sounds consistently better that way. This of course won't require endless flip-flopping of speaker leads. It's something you merely do once at the amplifier. Mind you, this adjustment is not about transient fidelity. It primarily affects timbre and tone. It's thus different from absolute polarity effects but could be the audibly more meaningful choice to make. That depends on your amplifier/speaker interface.
Finally, there's proper AC polarity. Furutech for example adds an AC polarity indicator to some of its power bars to confirm without add-on gizmos whether your wall outlet is wired correctly or not. If you're on the US three-prong system and find that your wall outlet is miswired, you can't just flip the plug as you can with EU Schuko plugs or speaker leads. You'll have to rewire the outlet. But even that is no guarantee that some power transformer inside your equipment may not be wired up wrongly. A highly credible manufacturer and modifier told me that this isn't quite as rare as it may sound but that the differences are quite audible. Welcome to the polarity/phase conundrum. At least now you know what those particular chat room threads are about that routinely flare up on this subject with much contentiousness. If you have a so-called phase switch or polarity inverter on one of your components, flip it and see whether it makes an audible difference. In theory, it should. In practice, it may require an idealized circumstance such as mono playback of a single instrument over a single-driver zero-xover speaker to not be masked. In which case, absolute polarity is of only academic concern to most listeners whose circumstances introduce other playback artifacts that mask the absolute polarity consideration.
The best most of us with multi-driver stereo speakers in reverberant acoustics can probably hope for is to have the majority of recorded transients in the audibly most obvious range register in absolute polarity at our ears most of the time - as a compression rather than decompression event. The rest of the time, we'll suffer the opposite to likely end up close to where be began. Wth a 50:50 probability of getting it right or wrong. Much ado over nothing? You tell me.
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