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Old 7th July 2009   #110
UnderTow
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Quote:
Originally Posted by B.A.S.E View Post

1) Is that polarity or phase that has to do with whether the speaker membranes go up and down ?
Short answer: Polarity.

Long answer: With a periodic wave you can also "invert the polarity" by shifting the phase by 180 degrees but you end up with a delayed signal. Depending on what you are doing, this might be an issue or not.

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2) I know it's mastering and not mixing, but is it wise to shift the phase of only one stereo channel ?
No! Unless you are looking for some weird effect.

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I do that on my sinewave basslines and usually, I found it help getting with some mixing problems I have.
This is a very bad idea! Maybe one of your speakers (or some other equipment in your system) is wired incorrectly?

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The only thing is that so-called "phase cancellation" when it goes mono.
Not just in mono, if you stand on a line stretching right between the two speakers it will also cancel out. Don't do it!

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3) I don't quite understand the difference between polarity and phase invertions even with what I tried to grasp upon the internet...
If I take a sinusoidal function, inverting the polarity is equivalent to have the negative value...
Not quite. See my other posts.

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Yet, if i take the same sinusoidal function and I flipped its phase, it means I add 180 degrees to it... thus, it should give me the negative value too, doesn't it ?...
Yes but it is time delayed while flipping the polarity doesn't change the timing. And as pointed out before, you can't shift the phase of a complex wave.

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4) what about all digital tracks ? there shouldn't be any difference ?
Not unless some piece of software/hardware is broken.

Si je peux te suggerer de relire mes messages precedants, les choses devraient se clarifier.

Alistair
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Alistair Johnston - TV & Film Post, Mastering, Sound Design
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