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Multiple mics: Phase correction, EQ, THEN timing corrections?

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Multiple mics: Phase correction, EQ, THEN timing corrections?

Postby noblestone » Fri Apr 19, 2013 3:41 pm

Two different acoustic guitars, a loud, boomy, old D-28 and a 60+ year-old, pre-Gibson, maple back and sides, Epiphone Texan (strung Nashville style). Both were miced with a U87 and an SM57. Without going into too much detail, the recordings are of pretty good quality.

But, not surprisingly, there are some phase issues. Gentle treatment with UAD's IBP on the 57 tracks resolves these well, providing a very warm and 3-dimensional sound from the Martin and an airy, lyrical sound from the Epiphone. This is with only the phase correction and minimal EQ (set up after the IBP in the signal chain).

But there are 4 acoustic tracks, along with several electric guitars and a piano which occassionally competes in the same frequency range. The acoustics were well played, but even microscopic timing variances creates muddiness in the attacks. There is one section of the song in which I plan to use primarilly the acoustics, and I need them to sound, psychoacoustically speaking, like one large guitar. Again, the timing is critical.

What I have done is correct phase, along with some mild EQ on both tracks, and bounce to a stereo file, with the two mics panned hard right and left. I, then, corrected the timing of each stereo track using the Warp feature in ProTools. Oh, I also automated the phase correction in order to compensate for some movement of the player during tracking.

Is this correct? I would like to maintain some separation of the two mics in order to spread the guitars out on the "stage" some, but maybe I should be blending the two signals more? I suspect that additional phase issues are being introduced, across the hard panned R and L stereo tracks, during timing correction. Or should I just go for mono bounce prior to timing correction, and use effects to spread the sound out a bit?

I plan to use only Distressors and some mild ambient verb (maybe a little spring, too), after the timing is corrected. Hopefully that's all that will be necessary, with EQ, obviously, to prevent problems with the overlapping frequencies from the other instruments.

Am I doing this correctly? Is there an easier way?

Sorry for the tome, and thanks in advance.
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Re: Multiple mics: Phase correction, EQ, THEN timing corrections?

Postby Tomás Mulcahy » Fri Apr 19, 2013 8:44 pm

First- welcome here. :)

What does it sound like? Post an example. Otherwise we're dancing about architecture (or creating tomes!).

"Correct" is an oversimplification. If it sounds good, it is good. For example, if the recorded ambience works, use that. If you need to add ambience, do that.

And I have to ask- Who recorded this? And if you wanted them to sound like one large guitar, why wasn't it performed that way i.e. rehearsed until they did play coherently?
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Re: Multiple mics: Phase correction, EQ, THEN timing corrections?

Postby Jack Ruston » Fri Apr 19, 2013 8:48 pm

Well elastic audio is a menace for phase relationships. If it sounds ok it is ok. But just watch for that. Are you sure you wouldn't be better taking one mic or other. I've very rarely found that stereo acoustics were useful in the context of a mix. Much the opposite.

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Re: Multiple mics: Phase correction, EQ, THEN timing corrections?

Postby Tomás Mulcahy » Fri Apr 19, 2013 8:55 pm

The rare times it did work were probably when a recognised stereo mic technique was used...
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Re: Multiple mics: Phase correction, EQ, THEN timing corrections?

Postby noblestone » Mon Apr 22, 2013 5:18 pm

To both of you, thanks for your rapid and well considered responses. I've been lurking around these boards for awhile and never posted.

After cogitating over the weekend, I realized several things.

1. If the recording (especially of an acoustic guitar) doesn't sound right, it probably isn't right. When I posted, I had just spent several frustrating hours trying to wrangle a square peg into a round hole. I wanted an easy way to fix something that really just needed to be thrown away.

2. It is correctly said that using one mic, in the absence of recognized stereo recording techniques, is probably worse than a waste; it is detrimental.

3. Correcting timing is OK, but if you have to correct more than just a little, you should just track it again, with more rehearsal.

4. Most importantly, it is really great that people with an abundance of experience are willing to take their own time, without recompense, to help someone with lesser experience and skill, such as myself, do something better.

So, thanks. I appreciate your help. If I ever get it right, I'd love to post something for your critique.
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Re: Multiple mics: Phase correction, EQ, THEN timing corrections?

Postby Tomás Mulcahy » Tue Apr 23, 2013 9:55 am

Seek feedback from musicians you are acquainted with in real life, or from friends who are reliable and frank in their judgements. :) I say that because often people post about audio problems, then when a file is posted it's almost always never as bad as they described. Not saying that is the case here, but it's worth considering that perhaps the standard is set to "imaginary".
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