No just make sure every source is the right way around and you don't need to change it at the preamp.
A polarity change is the same as a 180° phases change for ALL frequency's
but that just semantics.
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but that just semantics.
Oh no, I certainly wasn't referencing anything from my alma mater, I was thinking of the thread here by @René - Acculution.com .
The recording tutorial I read was this one:
https://www.uaudio.com/blog/understanding-audio-phase/
A pure impulse signal doesn't exist in music or in nature (except for Big Bang?). Even in a nuclear explosion, a rarefaction wave follows the compressed detonation front. Music is really about sine waves. And they have an uncanny quality of repeating.
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Now, if I had the power to make sure recording studios did the same, the problem would definitely be solved.
Ok, so then am I to assume that you are just trolling me?
I was thinking of the thread here by @René - Acculution.com .
The recording tutorial I read was this one:
https://www.uaudio.com/blog/understanding-audio-phase/
A pure impulse signal doesn't exist in music. Even in a nuclear explosion, a rarefaction wave follows the compressed detonation front. Music is really about sine waves. And they have an uncanny quality of repeating.
Continuous signals from strings, and speech vowels, are different than pluosive vocalisation, consonants, and drums strikes.
We do not listen exclusively to tones in the majority of music.
A pure Dirac delta function is usually what people use to describe a system’s behaviour in terms of theory.
If you want the woofer to suck back in at the start of an explosion, and the push out when the microphone sees the rare fraction wave, then I suppose you are free to that. but it is not correct… it is the exact inverse of correct.
So it is just not replicating the reality of the SPL that the microphone recorded.
To say that it does, or to say that music and movies sounds are more like tones than like explosive impulses is clearly in error for any action movies, and for most sounds other than monk’s constant humming.
Raindog123
Major Contributor
Your BBN buddies, in 2013 (ie, nearly ten years ago).
And distributed coherent RF comm transmitters (and receivers) are even bigger these days - for the same reasons, and multiplied by everything ‘swarming’.
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Why would you assume I am "trolling" you by referencing a thread on this very site on a related subject?
I am confident the music instruments - strings, piano, guitar, harp, brass, etc are MUCH more like tuning forks (another rather common musical accessory) than cannons and nuclear explosions.
You absolutely got me. I will have to apologize to my (nonexistent) Bolt Beranek and Newman "buddies." Happy New Year!Your BBN buddies, in 2013 (ie, nearly ten years ago).
And distributed coherent RF comm transmitters (and receivers) are even bigger these days - for the same reasons, and multiplied by everything ‘swarming’.
Raindog123
Major Contributor
Happy new year!
(To clarify, all I was referring to by ‘your buddies’ is that the [highly respected] BBN Technologies is an [advanced research] business unit of [highly regarded] RTX.)
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Probably because FFTs and phase are mentioned in a way that suggest that they can somehow be used to flip an inverted signal right side up.
I am confident the music instruments - strings, piano, guitar, harp, brass, etc are MUCH more like tuning forks (another rather common musical accessory) than cannons and nuclear explosions.
And also probably because the idea that percussion instruments are somehow producing continuous signals.
And also that you are apparently in the field of recording, and seem to suggest that incorrect polarity is as good as correct polarity.
If there is one thing that is easily measurable, and made correct, it is polarity.
The FFT question is best addressed to the originator of the other thread @René - Acculution.com . Phase or time shift can obviously be used to flip a sine wave upside down.
I am certainly not in the recording field. Structural analyst, Aero/Astro by education.
The recording tutorial I cited specifically talked about phase effects in recording drum kit with multiple mics, so it seems percussion instruments are not immune from this issue in the recording world.
Phase inversion is apparently a very common feature of recording hardware and software. There are even cheap XLR adapters that perform this function. Easy to figure out why
. The reality is very different from your last sentence... Unless it's common for recording studios to run Dirac tests through their full chains prior to pressing "record." And since it's the new year, it's time for...
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I don’t believe I need to ask Rene.
(He specifically talks about polarity versus phase in the link.)
If we time shift a delta function, then the delta function can be seen slides over a sample at a time or more..
The sine wave only look like it flips over, because the phase is lined up... It is not flipping it upside down with a time shift… it is sliding it sideways in the time domain.
In the FFT the amplitude stays the same, and the FFT bin’s phase rotates.
I’ll assume it is good.
FFT domain is a mathematical construct. Mere humans listen in the time domain. And a Pi phase shitted sine wave is an amplitude flipped one.
There really shouldn't be any controversy here at all. As shown in the math thread.
And that's why the recording industry tutorial instructs to time shift one track a very small time delta vs. the other - EXPLICITLY to correct for phase error. Or to move microphones a bit. Or to abide by the 1/3 rule in microphone placement relative to the source (to break up the 1/2 wavelength/phase relationship).
They seem to totally get it...If they don't always follow it. And please note, that their judgement call on all of this is "how does it sound?"
Sounds familiar?
"More Cowbell" is a classic. Sure, it's not 1812 overture, but that's how most of the world has fun.
Happy New Year!
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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.
That is exactly what I did in the 90s with nice speaker cable switches I made.
Now I plan to have a remote controlled XLR switch to do the same.
Our disagreement about phase and polarity appears to go back to undergraduate college physics and your insistence of substituting gun shots for sound of musical instruments. And for grown men it would seem to be not worth trying to resolve. I certainly don't have Clark's stamina for endless (and often pointless) argument. He did...and God bless him.
Perhaps it's his Harvard education in applied physics that encouraged it - down Mass Ave, at the Institute we just weren't taught that .So we should just let it be. If it's mildly important to me (frankly not sure after a quarter century), it's certainly irellevant to you.
. Why argue?
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Agreed.
Too bad the Clarke fellow is not around to help me with the explaining. Or the @René - Acculution.com fellow.
Too bad the Clarke fellow is not around to help me with the explaining. Or the @René - Acculution.com fellow.
Absolutely.
Clark is certainly not likely to make an appearance, but Rene can, if he likes.
IF it was recorded in absolute phase AND with a single mic AND played back on a phase coherent system AND in absolute phase than likely no.Here is an example of it of some percussion:
If we flipped the signal upside down, then the questions are:
- Would it sound different?
- Would we care?
Those are four "ifs" right there.
That's what Clark recognized 30 years ago. It's sad that this insight died with him. I am certainly a poor conduit of his knowledge.
Our hobby is particularly bad in retaining knowledge and building on it.
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There is no absolute phase in the mic.
We are talking about the polarity of the spikes pointing upwards versus downwards.
And there is no absolute phase in the speaker.
There is minimal phase being coherent across the audio band.
In fact phase has almost nothing to do with polarity.
I’ll just search for some séance books.
We should definitely let this go. We seem to live on different physics planets. Sophisticated math hasn't convinced you and, as we say in Russian (good math nation), "on the fingers" explanation didn't either. So it be.
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