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conflicting 3:1 explanations
Old 22nd September 2011
Originally Posted by TwardyLikeTank View Post
eh? Why not? Once they're aligned and in phase, aren't they aligned and in phase?

Wikipedia tells me that the speed of sound through air is only slightly dependent on frequency, so what's going on here?

(If you've lined up a distant and a close mic to the sample in a DAW and heard phasing, then I'll accept that a reasonable reason to have you opinion, but I would like to know if it's just your subjective experience rather then a fact.)

Thanks Kiwi.

Edit: Sweet post DigitMus.
Well yes, I've definitely tried it myself - I do this for a living after all!
I think it's been explained better than I can...but just remember that even a few samples out of phase can cause comb filtering. That "slight" difference may well be a few samples...probably no effect, but could be. It's also a case of wavelength - think about it, to get 2 200Hz sine waves aligned, you'd have to shift them a certain how far so you have to shift a 220hz wave? Now what if those are composite parts of a complex signal - how much do you shift it by then? This is why an ibp phase box isn't just a delay line, it's an all pass filter so you can alter this phase relationship.

I'm not the best at explaining this so I apologise if I've added to the confusion...suffice to say, the only time I've ever seen a pro engineer shift mics around time-wise is to delay or shorten room mics. It really tends to be something suggested by people working on their own sessions.
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