[James Tanner]

Hi Bunker

The down position would be Absolute Phase.

james

[bunkertoy]

Hi Bunker

The down position would be Absolute Phase.

james

Thank you Sir

[kernelbob]

Regarding absolute phase/polarity (both terms are used), the ear is a single ended device.  It is sensitive differently to compression and rarefaction components of a sound wave.  It is actually less responsive to compression.  Some speculate that this is an evolutionary adaptation.  Anyway, when you switch absolute phase, you are reversing these compression/rarefaction wave fronts to rarefaction/compression.

I use my preamp's remote control to select the correct phase for any recording.  Fortunately, this can be done from the listening position.  There is an easily heard difference between the two settings.  What I identify as the correct setting (again, for each specific recording) has deeper bass, a more balanced upper midrange & treble, and a more solid center image.  What I identify as a wrong setting for that recording lacks the deepest bass extension and a degree of bass impact.  The upper midrange/treble takes on a degree of hardness.  Instrumental timbre is not as realistic and natural.  That frequency range can take on a slightly nasal quality.

I emphasize that the identification of the correct absolute phase cannot just be done once for any specific system.  It doesn't matter if the system itself inverts phase or not since the non-inverting/inverting of the live performance varies from one recording to another, so you just have to adjust for phase by ear.  I've heard different releases of the same recorded performance having opposite absolute phase.

It's important that the polarity control paths for the non-invert/invert selections are the same.  That is, it's a bad idea for the "invert" setting to cause the signal path to go through an additional switch compared with the "non-invert" path.  The path with the extra switch will sound inferior, because that's what switches do.  Ideally, the phase/polarity control does not add an additional switch to the signal path at all.

[James Tanner]

Hi Folks

The other issue to consider is in a multi-mic recording (as most recordings are) each mic amplification of a specific instrument can be in or out of absolute phase.

james

[rollo]

Regarding absolute phase/polarity (both terms are used), the ear is a single ended device.  It is sensitive differently to compression and rarefaction components of a sound wave.  It is actually less responsive to compression.  Some speculate that this is an evolutionary adaptation.  Anyway, when you switch absolute phase, you are reversing these compression/rarefaction wave fronts to rarefaction/compression.

I use my preamp's remote control to select the correct phase for any recording.  Fortunately, this can be done from the listening position.  There is an easily heard difference between the two settings.  What I identify as the correct setting (again, for each specific recording) has deeper bass, a more balanced upper midrange & treble, and a more solid center image.  What I identify as a wrong setting for that recording lacks the deepest bass extension and a degree of bass impact.  The upper midrange/treble takes on a degree of hardness.  Instrumental timbre is not as realistic and natural.  That frequency range can take on a slightly nasal quality.

I emphasize that the identification of the correct absolute phase cannot just be done once for any specific system.  It doesn't matter if the system itself inverts phase or not since the non-inverting/inverting of the live performance varies from one recording to another, so you just have to adjust for phase by ear.  I've heard different releases of the same recorded performance having opposite absolute phase.

It's important that the polarity control paths for the non-invert/invert selections are the same.  That is, it's a bad idea for the "invert" setting to cause the signal path to go through an additional switch compared with the "non-invert" path.  The path with the extra switch will sound inferior, because that's what switches do.  Ideally, the phase/polarity control does not add an additional switch to the signal path at all.

  Very well stated. Agree 100%. Try it people if you have one. Then there are recordings where the bass is out of phase to the rest. Unlees one use a sub with polarity switch screwed.

charles

charles

[bunkertoy]

I get it now.... Since I have the option to switch the phase back and forth, why not listen for myself. I've never had this option before. Its very interesting. I'll definitely make use of my phase switch now. Love picking everyone's brain on this site.

[Speedskater]

Hi Folks
The other issue to consider is in a multi-mic recording (as most recordings are) each mic amplification of a specific instrument can be in or out of absolute phase.
james

Yes, some recording consoles have individual mic channel polarity switches. Often some of the channels are inverted to reduce pick-up of other nearby instruments.

[Vhond]

So this has nothing to do with polarity of the power supply?

[James Tanner]

So this has nothing to do with polarity of the power supply?

Hi Vhond

No its the polarity of the audio signal.  I hope this makes sense.

Lets say you are making a recording and you have a mic on the Sax's - when the Sax's blows a note the mic diaphragm moves INWARD and at the other end if all the electronics in the line (mic preamp, the recording mixing board the amps etc.) then the speaker drivers would move OUTWARD so the sound wave pressure you feel would be in absolute phase.

If anywhere along the recording chain gear inverts the phase then the speaker drivers would in fact move INWARDS - so it is out of absolute phase to the input. Also if your audio playback system has any component that inverts phase the same result will exist.

So one of the main problems that arises is that most recordings are multi-mic so there is no way of knowing what instruments in a recording have maintained absolute phase or inverted phase along the way. (there were a number of LP companies in the 79's and 80's that made recordings guaranteeing absolute phase). I usually listen to instruments with sharp transients to try and tell but the problem is you could get it correct for say the trumpet but have inverted the drums etc. in any specific recording. Then if you hit the phase switch you have the drums in absolute phase but now the trumpet is inverted.

james

[GSDaudio]

Would it be safe to say that given all the possibilities of absolute/invert mics in a recording an artist deliberately intended the sound to be that way?   And possibly the absolute/invert switch is only a simple EQ measure for preference at the instrument level?   I'm just getting into classical music so I have no idea  how to use that switch based on the assumption that  nobody notices or cares about phase with rock/pop genres. 

[James Tanner]

Would it be safe to say that given all the possibilities of absolute/invert mics in a recording an artist deliberately intended the sound to be that way?   And possibly the absolute/invert switch is only a simple EQ measure for preference at the instrument level?   I'm just getting into classical music so I have no idea  how to use that switch based on the assumption that  nobody notices or cares about phase with rock/pop genres. 

Hi GS

I am not sure on that - I have only done Jazz and Pop recordings so not sure how the Classical guys handle it.  I do know when I was involved in Movie soundtracks in LA they tend to use very simple mic techniques - typically 3 mics in what they call the Decca Tree - so I think there is probably a much better chance of maintaining absolute phase.

Also there have been a lot of blind listening test done to try and see if people can detect absolute phase polarity and the jury is still out.

james

[kernelbob]

I listen primarily to classical music including symphonic, chamber, and opera.  An example of great recordings with minimal numbers of microphones is the famous Decca "tree" which used three microphones, evolving later to sometimes include two more to capture more hall ambience [see https://en.wikipedia.org/wiki/Decca_tree].  At the other end of the spectrum are such misguided concepts as DG's "4D" setup that spotlights individual instruments and groups of instruments using many microphones with the mixing board tossing the salad.

If you're playing a recording with a hodgepodge of mixed microphone polarities, then there's no way to untangle that polarity mess.  Even with multiple microphones, I would expect recording companies such as Reference Recordings to at least get the polarity right, meaning consistent polarity across microphones.  Worse case... you should still hear gross differences such as more focused and articulated bass.  You may find that the quality of certain instruments or soloists may tip the scale to a better sounding polarity option.

[kernelbob]

Would it be safe to say that given all the possibilities of absolute/invert mics in a recording an artist deliberately intended the sound to be that way?   And possibly the absolute/invert switch is only a simple EQ measure for preference at the instrument level?   I'm just getting into classical music so I have no idea  how to use that switch based on the assumption that  nobody notices or cares about phase with rock/pop genres. 

As you explore classical music, try switching polarity on multiple recording, hopefully from your listening position using a remote.  Per my earlier post in this thread:

What I identify as the correct setting (again, for each specific recording) has deeper bass, a more balanced upper midrange & treble, and a more solid center image.  What I identify as a wrong setting for that recording lacks the deepest bass extension and a degree of bass impact.  The upper midrange/treble takes on a degree of hardness.  Instrumental timbre is not as realistic and natural.  That frequency range can take on a slightly nasal quality.

[Vhond]

Hi Vhond

No its the polarity of the audio signal.  I hope this makes sense.

Lets say you are making a recording and you have a mic on the Sax's - when the Sax's blows a note the mic diaphragm moves INWARD and at the other end if all the electronics in the line (mic preamp, the recording mixing board the amps etc.) then the speaker drivers would move OUTWARD so the sound wave pressure you feel would be in absolute phase.

If anywhere along the recording chain gear inverts the phase then the speaker drivers would in fact move INWARDS - so it is out of absolute phase to the input. Also if your audio playback system has any component that inverts phase the same result will exist.

So one of the main problems that arises is that most recordings are multi-mic so there is no way of knowing what instruments in a recording have maintained absolute phase or inverted phase along the way. (there were a number of LP companies in the 79's and 80's that made recordings guaranteeing absolute phase). I usually listen to instruments with sharp transients to try and tell but the problem is you could get it correct for say the trumpet but have inverted the drums etc. in any specific recording. Then if you hit the phase switch you have the drums in absolute phase but now the trumpet is inverted.

james

Very clear explanation: Thank you James