Some Test Tracks to check for Absolute Phase!

[Ghoostknight]

I tried to pass the audiocheck test as well but since I couldn't convince myself I hear a difference, I ended up just guessing.

yea its definitely not a "night an day" difference with these samples

most of the time i notice inverse phase stuff mainly with bass stuff, i think usual instruments like a normal guitar, dont get that often polarity switched either
but for me is clear: with the right material you can notice it, now its up to debate whether this might make a difference in your day to day listening

But i also feel like, atleast this is how i do it, when you got new gear, figure out once what is correct polarity in your system, and set it and forget it, imo there is no reason why someone would "want" inverse phase, i think most that actually have inverse phase in their system are simply not aware and even if they care, they will find many references to people saying it doesnt matter

I got a 12/12 on that as well but to my ears the saw wave was easier. For the saw wave test, I didn't have to reference A and B, I just kept playing X and knew immediately if X is A or B. For the impulse, I had to play A and B before deciding on X to get consistent results.

hmm interesting, i never tested with a saw wave but nice to hear the impulse tones work for others too, the impulse tone is probably more "like music"

i guess a saw wave has a even "sharper" impulse characteristic

in theory, only the first half sinuswave "should" matter with absolute phase, i think with transients it becomes apparent, tho i wonder why i hear such a consistent difference with the more or less "static" bass guitar in the music sample i posted above but maybe because it consistent of many "transients" troughout

 

[gregorio]

Can I ask, because I have no audio engineering knowledge at all, how does one know the phase of the various recording gear used in the production ?

Generally one doesn’t. What makes this thread irrelevant is that there is no “absolute phase” in the real world of commercial recordings, the phase is typically all over the place due to numerous factors/sources. As soon as you use more than one microphone to create a recording, there will be phase issues. In the case of say a drum kit or orchestral recording there will be a dozen or several dozen mics all in different positions, producing countless different phase relationships. So, the phase will be all over the place before you even start editing and mixing and then, not uncommonly we’ll invert the phase of some of the tracks/channels. After that, EQ and other effects are going to further mess with the phase and certain processes deliberately and specifically mess with the phase, such as a “shuffler” or “flanging” for example, and some do so by a full 180° which varies by time (typically in response to the setting of an LFO, low frequency oscillator). On top of all that, the phase is going to be affected on playback, the crossovers in the speakers will change the phase, as will the room acoustics and so will a DAC that employs a minimum phase anti-image filter.

Contrary to the very first line of the OP, it is not a controversial topic, let alone “so a controversial topic”, except apparently for him and maybe a handful of other extreme audiophiles.

G

 

[Ghoostknight]

Generally one doesn’t. What makes this thread irrelevant is that there is no “absolute phase” in the real world of commercial recordings, the phase is typically all over the place due to numerous factors/sources. As soon as you use more than one microphone to create a recording, there will be phase issues. In the case of say a drum kit or orchestral recording there will be a dozen or several dozen mics all in different positions, producing countless different phase relationships. So, the phase will be all over the place before you even start editing and mixing and then, not uncommonly we’ll invert the phase of some of the tracks/channels. After that, EQ and other effects are going to further mess with the phase and certain processes deliberately and specifically mess with the phase, such as a “shuffler” or “flanging” for example, and some do so by a full 180° which varies by time (typically in response to the setting of an LFO, low frequency oscillator). On top of all that, the phase is going to be affected on playback, the crossovers in the speakers will change the phase, as will the room acoustics and so will a DAC that employs a minimum phase anti-image filter.

Contrary to the very first line of the OP, it is not a controversial topic, let alone “so a controversial topic”, except apparently for him and maybe a handful of other extreme audiophiles.

please... maybe in your mind having 10-20% (obviously) messed up recordings means there is no point to care about this but everyone who notice this will also notice that in modern music there isnt that often obvious phase issues

also the way you produce electronic music... i think people are well aware of what is correct phase and what not

 

[The Jester]

I remember back in the 90’s there was a DAC with a Phase inverting button green and then red LED for phase reversal … plenty of CD’s around that supposedly “ sounded better” with phase reversed … some even went as far as putting little green and red stickers on the CD case for their preferred option …. Most didn’t bother ..

 

[Ghoostknight]

I remember back in the 90’s there was a DAC with a Phase inverting button green and then red LED for phase reversal … plenty of CD’s around that supposedly “ sounded better” with phase reversed … some even went as far as putting little green and red stickers on the CD case for their preferred option …. Most didn’t bother ..

well if we talk about "preference" than there is no point to argue about correct phase/polarity imo

personally i take inversed phase songs as what they are, what the producer heared/intended (and i hope they heared it with a correct polarity playback system), i dont bother switching phase for particular songs personally and like i said, i havent come across modern songs where its obvious that the whole track is reserved, "i think" i found one song a few months ago, but i dont remember which one

Also if we take microphone setups, lets say phase is shifted by 30 degree, imo 30 degree is still better than 210 degree for example

not uncommonly we’ll invert the phase of some of the tracks/channels.

yes, to avoid cancelation between tracks because it makes "more sense as a whole"

IMO while phase issues might be audible actual frequency response cancellations are far more audible... so pick the least poison which is altering the phase...

After that, EQ and other effects are going to further mess with the phase and certain processes deliberately and specifically mess with the phase, such as a “shuffler” or “flanging” for example, and some do so by a full 180° which varies by time (typically in response to the setting of an LFO, low frequency oscillator). On top of all that, the phase is going to be affected on playback, the crossovers in the speakers will change the phase, as will the room acoustics and so will a DAC that employs a minimum phase anti-image filter.

Well, there is always a way to make it worse, thats no reason for not caring for a approximiation of the "ideal"

 

[gregorio]

Also if we take microphone setups, lets say phase is shifted by 30 degree, imo 30 degree is still better than 210 degree for example

Sure but if you’re going to play the “let’s say” game, then “let’s say” the phase is shifted by 160° or 540°, what is better then?

yes, to avoid cancelation between tracks because it makes "more sense as a whole"

No that is not why we sometimes flip the polarity of a channel.

IMO while phase issues might be audible actual frequency response cancellations are far more audible... so pick the least poison which is altering the phase...

Again, no! There are circumstances where we want some phase cancellation that is audible in the freq response. You state or at least imply you are an audio engineer but then make assertions that an actual engineer would not make!

G

 

[Ghoostknight]

Sure but if you’re going to play the “let’s say” game, then “let’s say” the phase is shifted by 160° or 540°, what is better then?

540 - 360 : 180

imo 160 is the better one

No that is not why we sometimes flip the polarity of a channel.

Well sorry, actually if you talk about 2 mic setups you may flip one mic's polarity, so the recorded phase lines up with eachother because of different distances from mic to sound source, and i guess you could in theory line them up "perfectly" instead of just flipping the polarity "to make them somewhat lineup"

Again, no! There are circumstances where we want some phase cancellation that is audible in the freq response. You state or at least imply you are an audio engineer but then make assertions that an actual engineer would not make!

Why is artistic use of phase important here? let them do their thing

 

[Ghoostknight]

the point is absolute phase is audible, no matter how messed up the actual phase is of a particular song


just make sure you listen to it like the artist intended

 

[bigshot]

As long as it’s in relative phase, it’s fine.

 

[The Jester]

540 - 360 : 180

imo 160 is the better one


Well sorry, actually if you talk about 2 mic setups you may flip one mic's polarity, so the recorded phase lines up with eachother because of different distances from mic to sound source, and i guess you could in theory line them up "perfectly" instead of just flipping the polarity "to make them somewhat lineup"


Why is artistic use of phase important here? let them do their thing

With speaker crossovers a second order network is 180 out of phase, so with a midrange and tweeter reversing the polarity of say the tweeter results in a slight bump in the frequency response instead of a severe dip at the crossover frequency … a fourth order network is 360 out of phase which is in phase with a slight time delay which can be used to time align the acoustic centres of the drivers, be hard to hear phase errors on a two way system with a basic cap and inductor crossover, maybe easier with headphones and especially electrostatics …

 

[Ghoostknight]

With speaker crossovers a second order network is 180 out of phase, so with a midrange and tweeter reversing the polarity of say the tweeter results in a slight bump in the frequency response instead of a severe dip at the crossover frequency … a fourth order network is 360 out of phase which is in phase with a slight time delay which can be used to time align the acoustic centres of the drivers, be hard to hear phase errors on a two way system with a basic cap and inductor crossover, maybe easier with headphones and especially electrostatics …

well lets go by a 2 way design

my speakers cross over at around 1,8khz i think
if we look at the phaseshift of the low crossover section it probably begins to shift at 1khz or so, phase under 1khz will probably stay relatively flat in correct phase

usually the tweeter is wired out of phase, because inverted phase is imo more audible with lower frequencys

a subwoofer crossover might just mess stuff up enough that phase linearity becomes less audible, but i also think you should orient yourself at the "ideal" and see what is actually possible in your setup

unfortunaly because of speaker crossover you never get an ideal perfect absolute phase across the whole frequency range (unless you use one single wideband driver)
but i would still "try to aim" to get the polarity correct where its the most audible, this probably depends on your speakers

 

[bigshot]

Not having perfect phase in a speaker system isn’t unfortunate. It’s part of the dimensionality that makes speakers superior to headphones.

 

[The Jester]

well lets go by a 2 way design

my speakers cross over at around 1,8khz i think
if we look at the phaseshift of the low crossover section it probably begins to shift at 1khz or so, phase under 1khz will probably stay relatively flat in correct phase

usually the tweeter is wired out of phase, because inverted phase is imo more audible with lower frequencys

a subwoofer crossover might just mess stuff up enough that phase linearity becomes less audible, but i also think you should orient yourself at the "ideal" and see what is actually possible in your setup

unfortunaly because of speaker crossover you never get an ideal perfect absolute phase across the whole frequency range (unless you use one single wideband driver)
but i would still "try to aim" to get the polarity correct where its the most audible, this probably depends on your speakers

The other way of accurate time alignment is raked or curved baffles like Focal etc or even seperate discrete enclosures like Wilson, B&W etc …
Less effect sonically than using crossovers or “all pass” delaying networks …Not high on the WAF sometimes though …
All aiming for an apparent single point source ….
Fortunately the human ear isn’t very good at resolving phase at lower frequencies so phase errors in a 2 way system maybe less noticeable than the higher crossover point of midrange to tweeter …

 

[castleofargh]

I tend to measure a few things in a loop when I get new gear, to verify that nothing is obviously wrong and that I didn’t pay for fake marketing performances. If after the most basic sweep in REW, I see the impulse looking down, I’ll do something about it(so far it’s been some cable wrongly soldered and that happened twice in a decade of purchasing way more than I needed to, mostly among the cheapest offerings on the market).
I also got one IEM someone sent me to measure, where the left and right bass drivers were out of phase. No idea if that was on purpose or absent-minded soldering on that one pair. It sounded strange but oddly nice.
That is the full extent of my concern. It's one of the 1000 and 1 audible but irrelevant factors of my audio life. In this case, I can confidently say that I look it up as a maniac and not as a concern for a better listening experience.

 

[bigshot]

I have KEM speakers with a radial design that supposedly improves phase. I can’t discern any difference in that regard as opposed to my regular box speakers.