omnis

[FALKEN]

going to record drums tonight, using a mic on the bass drum, snare, and two dynamic omni overheads. I have a few questions that maybe some of you smart people out there can answer. I am most concerned with the positioning of the omnis.

1. do they have to be a specific distance from the snare mic to avoid phasing?

2. I have read on here about using onmis in an xy setup, but this confuses the hell out of me. how does this accomplish anything? it seems to me that both mics would pick up the exact same sound, regardless of the angle between them.

3. if i decide on a spread setup (is this advisable?) which I have always used, since now I am using omnis for the first time, do I have totally free reign on how far spread they are?

Thanks!!!

 

[PhilGood]

Sorry this is a late response. To answer your question, omni mics actually have some directionality to them. X/Y might work, but apart would be better. Harvey Gearst on the mic forum records that way. I've tried Behringer ECM8000 omnis as overheads and that's how I had to do them. They sound good because they're ruler flat on the response chart. Very real imaging.

You will have to play with position to determine phase problems. Generally, if they are spread apart and pointed in the same direction you won't have a problem. A good trick is if your preamp has a phase reversal switch, turn ONE on and place the position where they cancel each other out. Then turn it back to it's original position and the mics will be perfectly in phase.

 

[FALKEN]

if you were to reverse the phase on one of them and the sound just cancelled out, than it would prove my notion that using omnis in an x-y pattern does absolutely nothing.

I also do not understand how m-s can possibly create a stereo image at all. it seems to me that both channels would have to be panned center. since one microphone is picking up both sides, i fail to see how this can create stereo. maybe i am the dumbass.

 

[PhilGood]

if you were to reverse the phase on one of them and the sound just cancelled out, than it would prove my notion that using omnis in an x-y pattern does absolutely nothing.

I also do not understand how m-s can possibly create a stereo image at all. it seems to me that both channels would have to be panned center. since one microphone is picking up both sides, i fail to see how this can create stereo. maybe i am the dumbass.

Uh, that's a little vague. The phase problem is caused by the mic's polarity. If you have two sine wave's going in opposite directions and then overlapped, they will cancel each other out. If you get them both going the same direction you have max efficient signal. If the diaphrams are spaced so that one catches a sound wave before the other (exaclty half a wave), they can be out of phase.

It doesn't matter if they are x/y or spread apart. The leakage from the other mic will cause a problem. The phase switch allows you to find where they cancel when one is reversed so that when the one is switched back, they match. You not trying to cancel for the recording.

I agree that omni's in an X/Y pattern is probably useless. Remember though, omni mics are not actually true omni. They are somewhat directional. I think spaced apart over the kit is MUCH better.

To me one over the left side and one over the right is great and it WILL be a good stereo image.