Absolute Polarity - Myth or "Important"?

[charleski]

Testfile of sensitivity to absolute phase and phase rotation.
If you hear a steady-state tone you're phase-deaf. If you hear a cyclic timbre change pattern you're not.

I can hear this if I turn the volume up, but at a lower level it's inaudible. If I turn the volume to max it becomes so apparent that I wonder whether this is just exciting a resonance in the crappy speakers I have on my PC. The timbre change happens where the cursor is:

 

[solderdude]

Science has proven absolute phase differences can be audible with certain signals, especially when AB switching is possible.
To some this is important, others don't care or don't think it is sound degrading or affects the music itself.

I have read a few reviews and customer findings of the HE400SE. Yet no one noticed the absolute phase is wrong in this model. I did not notice it either and only found out because I also measure phase otherwise I would not have known and would be oblivious just like other reviewers owners.
Simply because it is not a sound changing experience.

Some are glad they can toggle phase (easy with software or when a switch is present). Dimitry wants to do this on the fly, using a remote on all of his sources. Most don't care and understand why.

The box for doing this isn't commercially available but in a few months one will exist and Dimitry can have fun switching.
I could even incorporate a switch undoing the phase rotation and then it can be used as an extra (remote controlled) input or A-B device if he wanted it to.

 

[Holmz]

Science has proven absolute phase differences can be audible with certain signals, especially when AB switching is possible.
To some this is important, others don't care or don't think it is sound degrading or affects the music itself.

I have read a few reviews and customer findings of the HE400SE. Yet no one noticed the absolute phase is wrong in this model. I did not notice it either and only found out because I also measure phase otherwise I would not have known and would be oblivious just like other reviewers owners.
Simply because it is not a sound changing experience.

Some are glad they can toggle phase (easy with software or when a switch is present). Dimitry wants to do this on the fly, using a remote on all of his sources. Most don't care and understand why.

The box for doing this isn't commercially available but in a few months one will exist and Dimitry can have fun switching.
I could even incorporate a switch undoing the phase rotation and then it can be used as an extra (remote controlled) input or A-B device if he wanted it to.

It is not phase rotation…
It is polarity switching.

 

[solderdude]

polarity switching = 180 degrees phase rotation for all frequencies.
potáto, potàto.

 

[Lambda]

Now, if I had the power to make sure recording studios did the same, the problem would definitely be solved.

it is "right" how ever it is recorded.
You don't go in museum an improve/fix the pictures do you?

 

[mansr]

Take an impulse function and do the FFT… I suppose we could move each bin 180 degrees… but it is easier in reality to swap the + and - cables at the speaker.

Why do an FFT, the phase shifts, and then an inverse FFT - to get back to the time domain signal in the correct polarity… when we can just swap the cables?

And we should not need to talk about multiple mics, if we cannot get the polarity right on a single mic.
Phase has nothing much to do with the polarity being wrong.

It's the exact same thing since fft(-x) = -fft(x). Obviously, flipping the polarity is practically simpler, and referring to it as such would avoid much of the confusion seen in this thread.

 

[DimitryZ]

it is "right" how ever it is recorded.
You don't go in museum an improve/fix the pictures do you?
View attachment 176173

If every recording was a masterpiece, then tone controls would be blasphemy.

 

[DimitryZ]

It's the exact same thing since fft(-x) = -fft(x). Obviously, flipping the polarity is practically simpler, and referring to it as such would avoid much of the confusion seen in this thread.

In the recording industry the term appears to be "phase inverse."

 

[jsrtheta]

Interesting conclusion. If the difference is audible (and apparently substantial), then it's up to the listener to choose their preference. And we are very good at that .

I still get the feeling that you perhaps spent a bit too much time with Johnsen. Maybe did his infamous "triple-blind" test?

It makes me wonder if you're seeking an answer that allows you to classify recordings as "right" or "wrong". That way madness of a sort can lie.

 

[jsrtheta]

However, since it can be important with some recordings and in some systems, why not have facilities to explore it?

Certainly in our hobby, among mind-boggling "devices" claiming really bizzare "improvements," polarity switching stands out as far more rational - and much less expensive.

And no less stupid. Seriously, this has been explored, explained tested and resolved again and again.

There is no unicorn. Not even a pony.

 

[DimitryZ]

I still get the feeling that you perhaps spent a bit too much time with Johnsen. Maybe did his infamous "triple-blind" test?

It makes me wonder if you're seeking an answer that allows you to classify recordings as "right" or "wrong". That way madness of a sort can lie.

I remember spending a few hours in his loft, which was in the old waterfront industrial area of Boston. I read other folks online reminiscing about him (he passed in 2020) and now also remember it was called The Listening Room. I came with an audiophile colleague and he chatted our heads off. We listened to his system but it was very casual. I bought his book out of politeness, but don't remember actually reading it afterwards. It was and is definitionally obvious that phase is an uncontrolled variable in most recordings except a handful of audiophile labels that mostly didn't record interesting music.

On some recordings, system phase inverse can make them "righter." As I explained, there is nothing "wrong" with a recording or a track that was put down in reverse polarity - it's just the way it is. You can continue listening to it in the opposite polarity (on a phase correct system) or invert system phase to match the recording.

Either way, it's your call. And with a remote, it's just a click.

 

[DimitryZ]

And no less stupid. Seriously, this has been explored, explained tested and resolved again and again.

There is no unicorn. Not even a pony.

And thank you, for your thoughtful, well-considered and polite insight.

It facilitates me being an infrequent visitor here.

 

[Thomas_A]

My take is that if you play mainly with digital files and notice a difference, you can always flip the recorded file itself, to the one that sounds best. If you have a simple remote switch, the listening session to determine the best can be done fast. Flip the file to the best sounding, and be done. Wrong polarity in bass sessions is at least in my ears audible and also be annoying and harsh in a few instances. But as said before, it is limited to a few records in bass region.

That is why I wish back a polarity switch on DACs. I would buy one, if it is not to expensive.

 

[jsrtheta]

I remember spending a few hours in his loft, which was in the old waterfront industrial area of Boston. I came with an audiophile colleague and he chatted our heads off. We listened to his system but it was very casual. I bought his book out of politeness, but don't remember actually reading it afterwards. It was and is definitionally obvious that phase is an uncontrolled variable in most recordings except a handful of audiophile labels that mostly didn't record interesting music.

On some recordings, phase inverse can make them "righter." As I explained, there is nothing "wrong" with a recording or a track that was put down in reverse polarity - it's just the way it is. You can continue listening to it in the opposite polarity (on a phase correct system) or invert system phase to match the recording.

Either way, it's your call. And with a remote, it's just a click.

Did you read the exchange I linked to in The Audio Critic?

 

[DimitryZ]

Did you read the exchange I linked to in The Audio Critic?

Yes, and it really sounded like him. Made me *kinda* miss him.

I do remember him boasting of clever retorts to his critics he had come up with. The one he was most proud of (at least in that conversation) was "I have a physics degree from Harvard that says you are full of shit."

 

[DimitryZ]

This is a good, if long tutorial on how phase effects and phase inversion can occur in multi-mic recording sessions and how to counteract it.

Phase Demystified

Phase interactions are well known for their ability to destructively interfere with recorded signals, but an understanding of the process can turn it into one of the most powerful creative tools available to you.

www.soundonsound.com

 

[Holmz]

It's the exact same thing since fft(-x) = -fft(x). Obviously, flipping the polarity is practically simpler, and referring to it as such would avoid much of the confusion seen in this thread.

Right but the presenatation of the topic had at least 3 things going on, (confounding the topic):

• There are microphones or individual recording electronic, that are phase inverted
• There are multi mic’ed sessions where engineers flip invert the phase
• There are speakers with drivers that flip (invert) the phase for every other driver

May argument was that #3 is not a great place to be if one wants phase coherence.

So the “fft(-x) = -fft(x)” is not overly handy unless one has a FIR based DSP and is doing some XO correction… Or is using an active XO strategy.

... Wrong polarity in bass sessions is at least in my ears audible and also be annoying and harsh in a few instances. But as said before, it is limited to a few records in bass region.
….

Is ^that^ more in cello sounds or drum sounds?

 

[Thomas_A]

Right but the presenatation of the topic had at least 3 things going on, (confounding the topic):

• There are microphones or individual recording electronic, that are phase inverted
• There are multi mic’ed sessions where engineers flip invert the phase
• There are speakers with drivers that flip (invert) the phase for every other driver

May argument was that #3 is not a great place to be if one wants phase coherence.

So the “fft(-x) = -fft(x)” is not overly handy unless one has a FIR based DSP and is doing some XO correction… Or is using an active XO strategy.



Is ^that^ more in cello sounds or drum sounds?

Bass guitar mainly, where I heard it. Diana Krall example here, a series of bass sounds flipped 180-0-180-0-180 etc.

allpass2.wav

Shared with Dropbox

www.dropbox.com

 

[DimitryZ]

Right but the presenatation of the topic had at least 3 things going on, (confounding the topic):

• There are microphones or individual recording electronic, that are phase inverted
• There are multi mic’ed sessions where engineers flip invert the phase
• There are speakers with drivers that flip (invert) the phase for every other driver

May argument was that #3 is not a great place to be if one wants phase coherence.

So the “fft(-x) = -fft(x)” is not overly handy unless one has a FIR based DSP and is doing some XO correction… Or is using an active XO strategy.



Is ^that^ more in cello sounds or drum sounds?

The last recording tutorial I linked to explores even more possibilities of phase mischief.

And as an early "phase adherent" I purchased phase coherent speakers - Vandersteens, Magnepans, Quads and Eminent Technology.

 

[jsrtheta]

Yes, and it really sounded like him. Made me *kinda* miss him.

I do remember him boasting of clever retorts to his critics he had come up with. The one he was most proud of (at least in that conversation) was "I have a physics degree from Harvard that says you are full of shit."

Yeah, he mentioned Harvard all the time, usually to badmouth it. I grew up in the Boston area and I wasn't impressed.

Did you read Aczel's response?