Phase reverseal after tracking

[bennychico11]

The greatest test would be to make a copy of the file, invert the copy and play them at the same time. If they cancel completely it was not destructive. Anyway, what makes you think that the phase switch on the trim plug is any better at inverting the phase than the offline process?

true, I didn't post that 'cause people probably would have thought it was just a blank file

but yes...i just did invert #101 on the file and played it right in time with the other one. 100% cancellation. You'll have to take my word on that one

 

[Light]

Maybe you missed it - Inverting IS reversing the phase.

Actually, it's NOT. You can't reverse or invert phase, period. Phase is a time issue, so unless you can invent time travel, you can't do it.


Now, on the other hand, POLARITY, which is what is actually being talked about here, that you can reverse or invert. There is no such thing as a phase switch. They are mislabeled polarity switches, thanks to the marketing department.


I know, everybody gets taught that phase=polarity, but it simply is not true. It only ever LOOKS true when you have a pure sine wave, but I rarely (never) have heard a pure sine wave in any recording.

This is one of those conventions of the recording industry that has a tendency to confuse the shit out of newbes.


Light

"Cowards can never be moral."
M.K. Gandhi

 

[xstatic]

Whether or not Pro Tools does or doesn't "mangle" things, I wouldn't worry about it. It's good enough for most of the world so it can't be that bad.

The bigger picture here however is that the audio needs to have its polarity reversed. I can't imagine that any software would do such a bad job of that that it sounded better leaving it alone with improper polarity.

 

[pipelineaudio]

or showing off
there are a LOT of misconceptions of Pro Tools. I'd like to hear what some of your beefs are about how it "mangles" audio. And I'd invite you to read: http://protoolsforum.com/WhitePaper.html as well as the document it links to.

That is an EYE opening paper! I didnt realize PT used a 24 bit internal path and that entry and exit to and from plugs is 24 bit

Also Im not sure if I got this right but it appears the DSP calculations for the plugs are done at 48bit fixed, and that POSSIBLE a 56 bit accumulation is involved

I think I'll "upgrade" my native app signal path from 32 bit float or 64 bit (depending on the app Im running at the moment) to 24 bit and my plugins from 64 bit float to 48 bit fixed

 

[easychair]

That is an EYE opening paper! I didnt realize PT used a 24 bit internal path and that entry and exit to and from plugs is 24 bit

Also Im not sure if I got this right but it appears the DSP calculations for the plugs are done at 48bit fixed, and that POSSIBLE a 56 bit accumulation is involved

I think I'll "upgrade" my native app signal path from 32 bit float or 64 bit (depending on the app Im running at the moment) to 24 bit and my plugins from 64 bit float to 48 bit fixed

I think I detect some sarcasm, but I'm too ignorant to know for sure.

"How many neutrinos does it take to change a light bulb?"
"10 the 24th, if you disregard Schrodinger. "
"BWAAAAAAHAHAHA! Good one!"

 

[Dags]

But, it would appear that you have to do a "destructive" edit? Not cool.

Sorry for the confusion - I have given you the wrong impression of the process (I really should try to get more sleep)
If you make a copy of the audio file and invert the copy, then you still have the original to go back to.

To Quote bennychico11:

besides, is inverting really destroying anything? Nothing frequency or amplitude wise is being changed. Everything is just being flipped around

This is true, and it is really easy to undo again.
I called it destructive because it affects the waveform itself - not like a plugin you can just bypass at any stage during playback.

The method of stereo recording using a figure 8 mic is that you make the recording, copy the resultant file (call the copied file audio_inv.aif or whatever) and invert the copy.
You have then created the two sides of the original stereo signal - positive and negative, as dgatwood mentioned earlier.

While both files are panned to be central, you won't hear anything because they cancel eachother out. But once you pan them left and right, you'll hear the stereo image in all its glory!

Dags

 

[LeeRosario]

http://www.soundstage.com/maxdb/maxdb101999.htm


read and enjoy


the section I like is:

I don’t hear digital-domain polarity reversal, so can I forget about polarity then?

No! No way! There is still the issue about playing music as it was intended to be played back. There is a symmetry and rightness to establishing and maintaining proper system electrical polarity. Maybe it only makes a difference 5% of the time (a complete guess) -- that’s enough to justify maintaining correct audio signal polarity in your audio system. I don’t have a convincing overriding argument for maintaining proper audio signal polarity. It just seems like the right thing to do.

Some attentive readers may have noticed that if polarity reversal is not audible, perhaps all those loudspeakers being made with alternating driver polarity really aren’t a problem after all. Or maybe they still are. In the crossover zone you would have one driver contributing rarefactions while the next driver would be contributing compressions. How confusing would that be to your ears? It isn’t going to jump out at you for sure or nobody would be alternating driver polarity. If it is audible, it is without doubt at some lower, perhaps long-term, level.

 

[EleKtriKaz]

Actually, it's NOT. You can't reverse or invert phase, period. Phase is a time issue, so unless you can invent time travel, you can't do it.


Now, on the other hand, POLARITY, which is what is actually being talked about here, that you can reverse or invert. There is no such thing as a phase switch. They are mislabeled polarity switches, thanks to the marketing department.


I know, everybody gets taught that phase=polarity, but it simply is not true. It only ever LOOKS true when you have a pure sine wave, but I rarely (never) have heard a pure sine wave in any recording.

This is one of those conventions of the recording industry that has a tendency to confuse the shit out of newbes.

Exactly. Phase only enters into the picture when you're comparing two or more waveforms. Phase is a time relationship between two or more waveforms. Flipping the polarity on a single waveform will have consequences that extend to phase when played with other audio, but no one discrete waveform can have 'phase'. All waveforms have a polarity though.

Flipping the polarity will only change a waveform from completing cycles of positive amplitude to negative amplitude to completing cycles of negative amplitude to positive amplitude.

 

[easychair]

http://www.soundstage.com/maxdb/maxdb101999.htm

There is a symmetry and rightness to establishing and maintaining proper system electrical polarity.

The guy is an idiot, but I like this idea. Aside from the interesting part about hearing, the rest of the article pretty much highlights his ignorance of all things audio.

Even though he gives a fairly solid case for why absolute polarity may not matter due to our ears, I just feel better when my audio comes out the same way it went in, compressions and rarefications just the way they came from the source. Excluding polarity changes made by necessity or choice, of course.

 

[LeeRosario]

The guy is an idiot, but I like this idea. Aside from the interesting part about hearing, the rest of the article pretty much highlights his ignorance of all things audio.

Even though he gives a fairly solid case for why absolute polarity may not matter due to our ears, I just feel better when my audio comes out the same way it went in, compressions and rarefications just the way they came from the source. Excluding polarity changes made by necessity or choice, of course.

Well the thing I find particularly interesting is the speaker design. I don't care for the other stuff. For example, JBL claims to design thier speakers opposite the polarity of most, if not all other speaker manufacturers.

In the end they still sound normal, but I suppose they did it just to be different.

All the stuff that guy said, I suppose I'm too young in the game to say I've seen it all, so it hasn't happened yet.

 

[bennychico11]

Well the thing I find particularly interesting is the speaker design. I don't care for the other stuff. For example, JBL claims to design thier speakers opposite the polarity of most, if not all other speaker manufacturers.

In the end they still sound normal, but I suppose they did it just to be different.

All the stuff that guy said, I suppose I'm too young in the game to say I've seen it all, so it hasn't happened yet.

similarly, I was reading Bruce Miller's audio courses and found where he states:

Polarity standards are different in many countries. For example, European audio equipment is wired differently from American and Japanese audio equipment, and has the opposite polarity. That means that if you take a sound wave that pushes a speaker OUT on a balanced system in America and play it on a balanced system in London, the speaker will actually suck IN rather than push out...sounding COMPLETELY different. After mixing an album in Finland, I listened back in New York and thought it was wrong...until I reversed the phase on both the left and right side (so both sides pushed OUT together rather than sucking IN together) and the mixes were right. That is why my "MIX mp3" page has a comment about the polarity...so people can hear the songs as they were intended.

It intrigued me since there may be a lot of consumer stereos (ie. Sony) that are made in other countries with different polarity....and then we play back audio CDs that were recorded here in the US perhaps with studio monitors made here.
And then of course what about mixing and matching gear? A compressor made in Japan, and EQ from Germany, and reverb from the US for example.

 

[easychair]

Well the thing I find particularly interesting is the speaker design. I don't care for the other stuff. For example, JBL claims to design thier speakers opposite the polarity of most, if not all other speaker manufacturers.

In the end they still sound normal, but I suppose they did it just to be different.

All the stuff that guy said, I suppose I'm too young in the game to say I've seen it all, so it hasn't happened yet.

JBL doesn't do that anymore. They got on the AES standard long ago, probably fifteen or twenty years since they made drivers that way.

Here are a couple of things I found:

He talked about drivers in a box being out of polarity. What he doesn't get is that sometimes that actually is better for phase coherence. Crossovers produce phase shift. Having all the drivers mounted on a flat baffle often means their acoustic centers aren't matched up. That means more phase shift. Woofers are "slower" than tweeters. Even more. All these factors and more may mean polarity reversal of the tweeter helps give the best phase coherence for the listener. For any decent speaker, you should only have to be concerned with polarity at the inputs, not for each driver.

Like I said, I agree with absolute polarity. I'm kind of a stickler about it, actually. The guy just uses some misconceptions when discussing it.

The other thing was his discussion of digital vs. analog polarity reversal, with regards to switching polarity at the speaker leads. He makes the claim that reversing speaker leads "reverses the direction the audio signal is applied to the.......crossover". He then claims this may be why people can hear polarity reversal when they switch speaker leads.

EARTH TO AUDIOPHILE: The signal going to the speakers is AC. It's polarity reverses constantly. Current goes through the crossover both ways all the time. Switching the polarity at the speaker just determines which way it goes first, like any other polarity switch. It shouldn't make a difference. Maybe it does, but his factual error makes his findings suspect, to me anyway.

As for the rest, I don't know about wire directionality, and all that. And I do support the idea of absolute polarity, maybe just for my own peace of mind. But the guy just seems to not know much about how the stuff he talks about actually works, and draws conclusions from his misconceptions.