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Out of phase
Old 25th January 2011 | Show parent
  #31
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Interesting...I've heard of test-signals that can sound different when polarity-inverted, but I didn't think it could be the case with a "normal" audio signal like a voice.

Do you have any audio examples?
Old 25th January 2011
  #32
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2 Reviews written
🎧 15 years
Quote:
Originally Posted by Matti ➑️
Now that I know there is a standard of mics having + and - in a
specified way, why do I have a pair of new mics out of phase
We don't use "phase" to describe this, we use "polarity." Or at least us technosnobs do. Phase is time related, polarity is absolute. The reason why you have two mics that are of opposite polarity is because someone goofed when assembling them. But did you try them both with the same cable, into the same mic input, into the same sound card input (assuming that's how you checked them)? It could be that something along the way other than the mic is miswired.
Quote:
How do I decide wich ones are to the standard?
Say "Peter Piper picked a peck of pickled peppers" into the mic. Or just clap your hands within a couple of inches of the mic. That will produce a wave front with initial positive pressure, which should make a positive-going waveform. But make sure the cable is wired correctly and use the same signal chain for testing each mic.
Old 25th January 2011 | Show parent
  #33
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🎧 10 years
Quote:
Originally Posted by MikeRivers ➑️
We don't use "phase" to describe this, we use "polarity." Or at least us technosnobs do. Phase is time related, polarity is absolute
And how right you are!

Polarity inversion NOT Phase flip.

To invert polarity is to become 180 degrees out of phase with the uninverted signal.

And yes, under compression a mic should output a positive value and when undergoing rarefaction it should output a negative value.

However I will now only use the Octava MK219's for the bottom of the snare so I don't have to push polarity inversion any more.

D

Last edited by deltasigma; 25th January 2011 at 04:46 PM.. Reason: detail
Old 25th January 2011 | Show parent
  #34
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The problem was Oktava mics are wired to different standard than most of modern western mics. Anyways this is quite old thread.
It is easy to change the polarity of a mic

Matti
Old 25th January 2011 | Show parent
  #35
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🎧 10 years
Quote:
Originally Posted by AllAboutTone ➑️
No conjunction, only single vocal or spoken voice. A bit thicker with reverse phase so that tells me the mic is wired incorrect. Not one mic I own I have to reverse phase on a single vocal etc.
No disrespect, but I don't see how that is physically possible. To be sure I understand you, are you saying that using this one mic, on one sound source, you hear a difference in the signal when the polarity switch is flipped?

I'm curious if anyone has any theories on how/why this would be the case.
Old 25th January 2011 | Show parent
  #36
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If you listen your self with phones while singing / speaking to a mic the phase / polarity has an effect to your ears but not to others listening the same time through the monitors.

Matti
Old 25th January 2011 | Show parent
  #37
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🎧 10 years
Quote:
Originally Posted by audiogeek ➑️
I'm curious if anyone has any theories on how/why this would be the case.
This is a wild guess (as you are right it should make no difference when used on its own) but......

Maybe room modes?!??!

Speakers moving in first when they should be moving out creating slightly different phasing at the listening position?!?!

D
Old 25th January 2011 | Show parent
  #38
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I aswered already and now leave this 2 years old thread

Matti
Old 25th January 2011 | Show parent
  #39
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🎧 15 years
Quote:
Originally Posted by timlloyd ➑️
Interesting...I've heard of test-signals that can sound different when polarity-inverted, but I didn't think it could be the case with a "normal" audio signal like a voice.

Do you have any audio examples?
No I don't save stuff like that, its normal when the phase is reversed, the low is much less or different, almost sounds boxy with some things. Its simple either the speakers are pushing toward you or against. Reverse a kick mic with the kick mic only one being one and watch/hear the reverse in the speakers.
Old 25th January 2011 | Show parent
  #40
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🎧 15 years
Quote:
Originally Posted by audiogeek ➑️
No disrespect, but I don't see how that is physically possible. To be sure I understand you, are you saying that using this one mic, on one sound source, you hear a difference in the signal when the polarity switch is flipped?

I'm curious if anyone has any theories on how/why this would be the case.
Yes, same goes for a 57 on a amp, you can hear the difference in phase reverse.
Old 25th January 2011 | Show parent
  #41
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🎧 15 years
Quote:
Originally Posted by Matti ➑️
If you listen your self with phones while singing / speaking to a mic the phase / polarity has an effect to your ears but not to others listening the same time through the monitors.

Matti
Sorry I don't quite understand that one, I can hear it with phones, monitors etc.
Old 25th January 2011 | Show parent
  #42
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🎧 10 years
The post of Matti's you just quoted makes perfect sense to me.......I'm not sure I that a polarity inversion should sound any different without reference to another signal......if I bring up a kick on some headphones and invert, I can't hear a difference.

Now.....if I already thought there should be a difference and had rationalised it to myself, then pushing the button and hearing the little click might be enough to confirm my expectation bias.

I'm not saying that's what's happening.....but it might be. It's what I'll believe until I prove myself wrong or you post some files that demonstrate it. Remember....these files must null to -inf in order for what you're saying to be testable.....unless you're doing this in the analogue domain and there is something wrong with your inverting amplifier, actually making it sound different when it shouldn't.
Old 25th January 2011 | Show parent
  #43
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🎧 15 years
Quote:
Originally Posted by Matti ➑️
If you listen your self with phones while singing / speaking to a mic the phase / polarity has an effect to your ears but not to others listening the same time through the monitors.

Matti
That makes sense. It would essentially be comb filtering resulting from phase-related cancellation between the sound of one's own voice in his cranium and the sound of the cue monitor of his voice in the cans.

Thanks for the explanation.


And thanks to Mike for hitting the polarity/phase terminology issue. Some of us old stick-in-the-mud types get tired of always being the one to jump in on some of these evergreen terminology issues.

(But this is clearly one where many gear makers, particularly mixer makers, themselves were largely to blame for mislabeling polarity reversal switches as 'phase' switches. When the professional level mixing desk you just dumped many thousands or tens of thousands on says phase on its polarity reversal switches, who is Joe Yobbo at Bumfogg Studios in Podunk, Kansas, to argue? heh )


Mike, since you've written your share of manuals and documentation and such, I have to ask: has this issue ever come up when dealing with a client who's commissioned you to write the docs/manual for a piece of kit that has the polarity switch mislabeled as phase?
Old 25th January 2011 | Show parent
  #44
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🎧 15 years
Quote:
Originally Posted by AllAboutTone ➑️
Sorry I don't quite understand that one, I can hear it with phones, monitors etc.
Are you sure about that?

You mean that you can tell the difference between two previously recorded clips, when the polarity of one is reversed?
Old 25th January 2011 | Show parent
  #45
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🎧 10 years
Quote:
Originally Posted by theblue1 ➑️
And thanks to Mike for hitting the polarity/phase terminology issue. Some of us old stick-in-the-mud types get tired of always being the one to jump in on some of these evergreen terminology issues.
+1....but don't worry, I'm one of the young-uns and I also jump on that one...

How about this though...........audio signal >> FFT analysis >> rotate the phase of each sinusoidal component by 180degrees individually, according to their wavelengths >> FFT re-synthesis >> what you have is a signal of opposite polarity to the input



so...
Old 25th January 2011 | Show parent
  #46
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🎧 15 years
heh

I see where you're going -- but I'm not exactly Mr Fast Fourier Transform heh so I'm not sure I even want to put a toe in that water...

Still, if I understand the basic principles of what you're proposing, would it not still be fundamentally a polarity reversal both in the particular as well as in the aggregate?
Old 25th January 2011 | Show parent
  #47
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🎧 10 years
Yes, it's just a different way of getting there. I'm still of the opinion though, that on analogue gear "polarity invert" is correct - because that's precisely what it's doing - Mr Fourier isn't allowed in analogue parties

....and I hope nobody mentions the Little Labs IBP....because they can't adjust the phase of all frequencies simultaneously....they're different and can't achieve a polarity inversion....
πŸ“ Reply

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