[woodsyi]

What is the correct phase?  Or should it matter when listening to a recording?

At the recent CAF,  I listened to same recordings with both phases at two rooms:  Salk/Lampizator and Daedalus/Modwright.

In both cases, one was better than the other and the favorable phase varied with music.  The gentleman with Gingko at Salk room, who was in charge of running the Big 7 Lampizator, told me the phase should match the original recording.  Is this correct?  It seemed so from what I heard.  If so, should every preamp have a phase switch to listen in correct phase?  We should toggle back and forth for every song?

[barrows]

Yes, absolute phase (or polarity) can matter.  But, the world is full of problems in this area, for example:

Some loudspeakers have drivers connected out of phase with each other (on purpose) as their crossover design requires this for good driver integration.

Not only are some recordings in reverse phase, but in some multi-tracked recordings some tracks will be in correct phase, and some tracks will be in reverse phase.

And, listening for correct phase and switching back and forth with every track is a big detractor from the listening experience.

So, what is one to do...

If you are interested in reading more about absolute phase, try google for: George Louis, the absolute polarity pundit

[RichPark]

Out of phase recordings have been a pet peeve of mine since I have been listing to recorded audio.  There are so many ways for a recording to get out of phase during the process that it's always nice to have a preamp which has a phase switch to play with.  I like to play with it to see if a dead recording comes to life when I use the phase toggle.  In a multi-track recording chances one of the channels will be out of phase (whether by design or accident). You may improve the vocals, but loose the bass when you invert the phase (just an example).  It can drive you nuts toggling the phase after each song but can be rewarding.  Hopefully you have a remote.

[BobRex]

You will also find that in multi-track recordings not all microphones / tracks are in phase with each other.  I'd like to think this was done on purpose, for the effect, but then again....

[Speedskater]

Yes, some recording consoles have polarity switches on individual channels. So a recording engineer may reverse the polarity on some of the mics. Probably to reduce cross-talk.

[kernelbob]

Regarding polarity or absolute phase, I've found that there isn't a consistent setting from one recording to another, even from the same label.  I select the correct setting on my DAC's remote.  It just takes a couple of seconds.  I often can tell if the sound is correct or not without having to test the opposite setting.  Non-audiophile visitors can also easily hear the difference in my system.  One thing though, I've found that if I invert polarity using a mechanical switch such as on a preamp, the difference is usually masked by the degradation caused by a change in the signal path, e.g. going through an additional switch.  I've found the best place to select the best sounding polarity is through the DAC's software.  Even then, some DACs do a better job than others in preserving the nuances that illuminate the sonic differences between absolute phase.

When phase/polarity is set to the setting that on a particular recording sounds best, I hear the following.  Deep bass is more extended into the subterranean region.  Overall bass is more dynamic with better impact.  Instruments have better upper bass to lower midrange balance with more natural timbre.  Overall there is a more relaxed sound.

By comparison, the less correct sounding setting for the same particular recording sounds as follows.  Bass is not as extended, sort of like the bass from a Naxos recording instead of a London/Decca.  Bass has less dynamic impact, a more rounded sound.  Upper midrange takes on a hint of nasality.  Why that is I don't have a clue, but the effect is consistent across many different record labels.  Female vocals can take on a degree of hardness.  Maria Callas is a poster child for this effect.

The more that ancillary equipment is improved, (e.g. power cords, IC's, speaker cables) the more distinct the changes in absolute phase/polarity have become.  I've also found that some DAC's reveal these differences better than others.  Delta/sigma DACs, in my experience, have tended to homogenize these subtle differences while R2R DACs pass along the differences more.

So, I wouldn't concern myself with whether the preamp, amplifier, etc. inverts polarity since roughly half of the recordings will need to have the setting changed anyway.  One more thing, I wouldn't own a system where I couldn't change the absolute polarity/phase from the remote.  Comparing the alternate settings from the listening position is a must.

Why there should be such audible differences in absolute phase may in part be related to the fact that the ear is a single-ended system and is not symmetrically sensiteve to the compression and rarefaction components of sound (it's less sensitive to compression).

Regards,
Robert

[STEREOmole]

Huh?

This makes no sense to me.  How to you determine "absolute phase"?  What is your reference? How do you know that your selection (whether to make the bass more extended or sound more relaxed) is what the producer and engineer intended? 

I also find it difficult to believe that any studio (even in the case of home/amateur recordings) would be incapable of preserving "absolute phase"...and even if they didn't, what difference does it make?  Unless the polarity of one channel only (right or left) gets reversed, which is nearly impossible in a pro studio or mastering house, it's a non-issue. 

Lastly, when you refer to multi-track recordings having tracks that are "out of phase" with each other as being a bad thing, it's somewhat misleading.  Mic placement in the studio (with multiple mics) can cause phase cancellation and require flipping the phase on one or more tracks so that the mix is 'phase coherent'.  It also helps if the Engineer previews all mixes in Mono to check for phase issues between right and left channels between individual tracks.  If there ARE issues with phase cancellation between tracks or mics, there's not much that can be done about it once the final mix reaches the Audiophile consumer, and certainly isn't going be fixed with a phase switch on a preamp.

[Vlad]

This is controversial subject since it is highly recording, system and listener dependent.

Srajan at 6moons gives a good explanation here:
http://www.6moons.com/industryfeatures/polarity/polarity.html

Vlad

[*Scotty*]

Generally speaking in a system that is not balanced,(ie. consisting only of positive signal hot and ground) absolute phase cannot be reversed via a simple switch. Phase reversal in a non-balanced system can only be reversed at the source in software, at the phono-cartridge pins or at the speaker terminals.
A special case could be envisioned however, in the event that there was an op-amp present in the signal path with an inverted output that could be switched to the output jacks in place of the non-inverting output. Although the argument against a simple extra switch would be in play.
Anyone playing Sheffield Lab recordings can benefit from reversing the systems absolute phase, as the recordings were done with equipment that had an inverted output. The vinyl records' liner notes recommend that the phase be reversed at the speaker terminals for the best quality playback.
Scotty'

[Russell Dawkins]

In a multi mic recording that is phase-confused, as many are where there is any "live off the floor" component, it might be advantageous to at least have the lead or solo voice in correct absolute polarity. It also can be important when the recording is of a simple nature, like a solo instrument or duet where both are very exposed. Some instruments naturally produce asymmetric waveforms.
Here's a trombone I recorded a couple of years ago; surprisingly asymmetric: