How to make sure top and bottom mics are in phase?

[MaKoRancid]

I never miced a snare drum with top and bottom mics, how can i make sure these are in phase?

[macr0w]

make a stereo track out of them and use that new BF correlation meter plugin.

[Chris Cavell]

If they are perfectly in phase, the meter will pin all the way to the right, if they are 180 degrees out of phase, the meter will pin all the way to the left, 90 (or 270) degrees out of phase is the middle of the phase correlation meter.

[jjhuntfox]

Cant you put a 1 band eq on one of the tracks, hit the 0 with a / in it button, that will reverse the phase and see how that changes the sound. If it gets thin and wimpy, its out of phase.

[1Nation]

If they are perfectly in phase, the meter will pin all the way to the right, if they are 180 degrees out of phase, the meter will pin all the way to the left, 90 (or 270) degrees out of phase is the middle of the phase correlation meter.

Can you adjust the phase from inside this plug in? I've been thinking about how cool it would be to see a plug in version of the IBP

[where02190]

I never use a bottom mic. If the snares are not prominant in the room and overhead mics I loosen them a bit. Less mics, less phase issues.

[Chris Cavell]

You can't really fix phase issues completely with any plugin that I know of unless it's 180 degrees out of phase (where simply reversing the polarity is essentially the same thing as a 180 degree shift). One of the reasons that tool talks about using it inparticular on bass is that all solid state devices (except for some very rare ones) usually have very poor phase response (think of a frequency response curve but instead showing phase against frequency instead of amplitude against frequency) in and around the upper two octaves of our hearing range, making these outboard tools sort of useless for many insturments. (The makers of the IBP make it sound like they've come up with a way to compensate for it, but really they've just split the human hearing range into two seperate bands that are adjusted in different amounts simultaneously...hardly an accurate operation across the entire spectrum) Many people think that when they nudge drum tracks to get everything to line up that they're fixing the phase issues; they aren't, just the time alignment of the attacks (and usually just the time alignment of a single drum across all the mics, not the entire kit). A phase correlation meter usually shows out of phase all the way to the left and in phase all the way to the right. They aren't tools for adjusting or fixing anything, just measuring devices that can give you an idea of the relative phase between two signals. I often use oscilloscopes in X-Y mode to perform the same sort of measurements. In can give you an idea of what type of information your stereo mix consists of. The absolute easiest way to fix a phase issue with the best certainty is to adjust the mic to find the best sounding position without phase problems (keeping in mind that a polarity reversal switch does effectively shift the signal 180 degrees and may open up more placement positions).

[littlelabs]

(The makers of the IBP make it sound like they've come up with a way to compensate for it, but really they've just split the human hearing range into two seperate bands that are adjusted in different amounts simultaneously...hardly an accurate operation across the entire spectrum)

I was just checking out for the first time the duc board and found this, I suppose it is too late to respond, but I am anyway. Being the designer of the IBP, I can tell you what is said in Mr. Cavells post is not accurate and obviously he doesn't understand what happens when you have two poles in a filter. In the IBP s case creating a phase vs. frequency curve across the audible frequency spectrum. In other words keeping the notes in phase up and down the neck, in most cases. It certainly will work on top and bottom snare (that is easy). Having the perfect reciprocal phase vs. frequency response for every situation the IBP can't do, but the filter was designed to work in more cases than not. Just as moving the mic helps sometime, but not every time. The beauty of the IBP is it allows you to keep the mics where they sound best individually, tweeking the phase issues out with the IBP.
so ...
Jonathan

Little Labs
Pro Audio Design, Manufacturing and Consulting
http://www.littlelabs.com/
vox/fax :323.851.6860

[Chris Cavell]

Hello Jonathan, and welcome to the board. I sincerely apologize if my post appeared to be a sort of "hit" on your product...that wasn't my intention at all. It certainly is a very useful tool...but as you stated doesn't always work with every situation. The same can be said about trying to fix phase issues with mic placement...you may be able to fix the issue only to completely lose the tone and sound that was achieved by the original placement with phase issues. Your tool opens up a wealth of possibilities in placement options that wouldn't be available otherwise and applaud you for developing it. It just doesn't work in all situations...but works very well in many.

So, are there any plans on the possible exploration of a plugin version...vst or rtas?

Cheers,
Chris

[mersisblue]

solo the two mics reverse the polarity , I might use meters but dont rely on them

where has some good advice but micing the bottom too allows you to switch the

snare mics maybe more a dramatic sound ? I like using a lot of mics in tracking