OH Phase issues?

  • Thread starter Thread starter Supercreep
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Supercreep

Supercreep

Lizard People
Hi, I'm trying to use a slightly modified x/y technique (the SDC capsules are as close as I can get them, but parallell on a plane - the capsules do not cross).

On a whim I reversed the polarity on one of the mics. It seemed like the sound suddenly had much more depth and a wider stereo image.

Is this kosher? Or is it just a sign I should reposition our OH to eliminate the problem?

Should one just go about flipping phase on various mics just to see what happens?
 
I this case (mics being in the 'same' position, i.e. going for 'x/y 'coherent'), no, unless you were correcting for flipped polarity in the first place.
If you were to pan them in there would likely be quite a lot of cancellation going on.
You should be able to do some experiments to check out the difference between 'out of phase from polarity inversion vs say spreading the mics but in polarity.
With most stereo mic set ups (at least the semi-coherent ones) an image is rather balanced L/R where out of polarity sort of just 'swims'..(?) :p
Check out 'ORTF stereo technique for example.
http://www.rane.com/par-o.html
 
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mixsit said:
You should be able to do some experiments to check out the difference between 'out of phase from polarity inversion vs say spreading the mics but in polarity.
Click to expand...


Thanks - Can you elaborate on these?

-Casey
 
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Supercreep said:
Hi, I'm trying to use a slightly modified x/y technique (the SDC capsules are as close as I can get them, but parallell on a plane - the capsules do not cross).
Click to expand...

I am not sure I follow... Are they side by side? capsules the same direction, or bodies parallel capsules facing opposite directions?

Supercreep said:
On a whim I reversed the polarity on one of the mics. It seemed like the sound suddenly had much more depth and a wider stereo image.

Is this kosher? Or is it just a sign I should reposition our OH to eliminate the problem?

Should one just go about flipping phase on various mics just to see what happens?
Click to expand...

One should always experiment! If you are recording to a computer, look carefully at both tracks and see if the mics are recording both the same polarity. Look for a snare hit or something, zoom in close to the initial transient and see if they both head "up" (positive) if they do but the start points of the transients are offset a little it is probably the distance between them that is causing the cancellation.

Tom
 
Yeah, with the mics that close to each other, it would be hard to get phase cancellation from them even if you tried, I think.

I'd go through the whole chain and make sure a pre-amp, channel or something doesn't have the phase flipped. I'm no expert on this, so it might very well be possible that you can get cancellation with mics that close, but it never happened to me so I'm sceptical.
 
I guess it's more like ORTF. The mics come together in a V shape and the capsules are about 1/8" away from one another.

I meant to say earlier that one mic does not cross over the other. So I guess in a sense they are looking at each other just a little bit:

\ / (the angle is a little different, but you get the idea)
 
Do you have clips? I don't know how to play drums yet, but I did set up 2 MSH-1's as overheads, just to try the sound.

How do you pan yours? Did it make a difference widening, or reducing the panning?
 
Dogman said:
Do you have clips? I don't know how to play drums yet, but I did set up 2 MSH-1's as overheads, just to try the sound.

How do you pan yours? Did it make a difference widening, or reducing the panning?
Click to expand...
Let's try to keep it down to 3 questions per post, ok????


:D :D :D :p :p :p
 
RAMI said:
Let's try to keep it down to 3 questions per post, ok????


:D :D :D :p :p :p
Click to expand...
But if I don't hurry, all the good questions will get asked....then I'll have to hijack the thread with Cheetos and butt peeing... :eek:
 
Supercreep said:
I guess it's more like ORTF. The mics come together in a V shape and the capsules are about 1/8" away from one another.

I meant to say earlier that one mic does not cross over the other. So I guess in a sense they are looking at each other just a little bit:

\ / (the angle is a little different, but you get the idea)
Click to expand...
Right. What we need here is a good 'mic site' link here. Something with 'stickies' with some nice big MIC THREADS ...
https://homerecording.com/bbs/forumdisplay.php?f=27 ;)
Capsules that close and angled like that is similar to 'XY, and the 1/8" lets just some of the high frequencies be out of phase. (As you increase the V' angle it's a wider image, decrease, more mono.)
ORTF puts the caps at the other ends of the \ / and has phase changes down into mids, as one of it's attributes. In other words 'a little looser' on purpose?

The experiment; Pan them both center. Invert the phase on one. Does it cut a bunch of the sound? Now you know which position is in/or out of polarity.
Now pan them back out, walk past the speakers L > R (or just shift your head back and forth.)
With a 'close to coherent set up like that, 'in phase should sound very different than out --same as if you flip one speaker. Very easy to pick up on onec you cue in on it.
Cheers.
 
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Casey, something I have tried, is spacing the mics a bit further apart, about 4", and playing with the panning. I think the post above yours goes into better detail. I just noticed that panned center, the sound was boxy, but panning further out, seemed to bring some crispness, and this is with the micspointing sort of parralell. When the ends were close together, it was louder, but not as bright sounding. Maybe experiment with moving the mics just a bit. :confused:
 
Casey, I'm using the method that's mentioned in the 20,000 page drum micing thread that's going around...I think by "Recordman" or whatever....Anyway, ever since I tried I never went back.
 
Tried the Glynn Johns thing last night. Interesting sort of space. Thanks.
 
tag, I need to read more about this later. Looks like a good thread~!
 
Results are pretty awesome. Glynn Johns works great, so long as you really want to hear some hi hat and snare. I think maybe for pop rock this is a pretty good technique.

Using this technique with a compressed room mic yields excellent results (for us).

Alas, all this excellence extends only to the sound, not the performance. :confused:


Thanks guys.
 
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