Capturing audio for a Christmas concert...

[daveswan]

Co-incident pair /\ Semi-spaced pair \ /
.........................r l............................. l r
For co-incident, the angle shoud be 90 deg, for ORTF. angle 110 deg, spacing between capsules 7", for NOS, 90 deg, spacing 12"

HTH,
Dave

Had to put dots in so the lr would line up properly

 

[Rylan Zolinski]

Very bad idea, if your objective is to record stereo. 25 feet apart, 5 feet in front of the group, might be appropriate for a LARGE choir and two mics that will be mixed down to one mono channel but not for a stereo recording. If you stand in the centre aisle down right in front of the stage looking at the centre of the group of kids, you'll hear them all just fine, won't you? But your ears aren't 25 feet apart, are they? Think in terms of angles - a pair of cardioids in an X/Y array are positioned together with their diaphrams directly over each, the axis' of their pickup patterns crossing and diverging at an angle of about 100 degrees. Think of an upside-down, horizontal "V" with its apex pointing at the centre of the group. The right-hand mic (the right leg of the inverted V) points at the left-hand end of the group and is connected to the LEFT stereo channel. The left-hand mic points to the right-hand end of the group and connects to the RIGHT stereo channel. This means ther stereo field is approximately a semicircle. If your draw a line bisecting the angle formed by the axis' of the two mics, it will point to the centre of the group you're recording. How far from the group needs to be determined by experiment during a rehearsal but roughly in the centreline about 10 feet away from the kids might be a good place to start.

How many kids could I pick up doing to the X/Y position? Like I said, there will be 200 of them. I guess my best bet is to try and squeeze them together as much as possible and extend the mic pole so it can adequately capture the kids in the back?

 

[daveswan]

The thing is, how big an angle do they make with the mic position? Are they in one long line?
If you've got several rows, then get your mics up as high as you can, typically I've put mics on a 14' stand in the past, certainly position your mics so they can "see" the back rows.
If you're in a school hall, can you fly the mics? This might be way to get them high without using a stand and blocking the audiance's sight lines.

Funny thing, I'm in a not too dissimilar position, as I'm getting ready to film our school's carol service, in the local church, 3 cameras and a PMD 661.
Dave

 

[Rylan Zolinski]

Welp, I just got back from the shoot. Having such small kids (kindergarten to grade 6) definitely helped since they can pack into a small gym very well. I don't know how others do it, but I set the mics up using the X/Y position and my XHA1 was able to sit on its tripod in-between both of the mic stands to avoid capturing the mics in the footage. I was capturing the audio about 12 feet away from the children since they were quite loud. They had audio playing throughout the gym (one of those sphere speakers) placed in the middle of the ceiling projecting music for what they were singing. We had the kids sing a song with the audio playing and then rewound the footage to test it with my headphones and I was pleased with it. I am no audiophile and I can't gauge how well it sounds compared to what audio gurus expect, but it definitely sounded good enough for me. Right when I got home I tested the footage on my television and I was very pleased considering I gained most of my information from you guys within the past few days with very little time to test the mics. Thanks a lot, I really appreciate it!

 

[Steve House]

How many kids could I pick up doing to the X/Y position? Like I said, there will be 200 of them. I guess my best bet is to try and squeeze them together as much as possible and extend the mic pole so it can adequately capture the kids in the back?

I once heard a master recording of the ful New York Philharmonic with the Metropolitan Opera Chorus that has been made at St Patrick's Cathedral, all recorded with a single stereo pair of mics in an X/Y arrangment for the entire ensemble. No reason a similar arrangement wouldn't cover a group of kids.

 

[Steve House]

Welp, I just got back from the shoot. Having such small kids (kindergarten to grade 6) definitely helped since they can pack into a small gym very well. I don't know how others do it, but I set the mics up using the X/Y position and my XHA1 was able to sit on its tripod in-between both of the mic stands to avoid capturing the mics in the footage. I was capturing the audio about 12 feet away from the children since they were quite loud. They had audio playing throughout the gym (one of those sphere speakers) placed in the middle of the ceiling projecting music for what they were singing. We had the kids sing a song with the audio playing and then rewound the footage to test it with my headphones and I was pleased with it. I am no audiophile and I can't gauge how well it sounds compared to what audio gurus expect, but it definitely sounded good enough for me. Right when I got home I tested the footage on my television and I was very pleased considering I gained most of my information from you guys within the past few days with very little time to test the mics. Thanks a lot, I really appreciate it!

Glad it worked out for you! Just FYI, there's no way you could put the camera in between the mics if they were arranged in an X/Y array. In X/Y, the mics are mounted together on a stereo bar to make an inverted "V", usually mounted on one stand with the diaphrams positioned one above the other, positioned as close together as possible without the mics actually touching each other. If you look down on it from above, the two mics would make an arrowhead pointed at the centre of the group you're recording. Take a look at this guide on the Schoeps website http://schoeps.de/documents/stereo-recording-techniques-e.pdf and also look at this Wiki article, about half-way down the page, for an illustration. http://en.wikipedia.org/wiki/Stereophonic_sound

 

[Rylan Zolinski]

I used two separate stands and positioned them in the X/Y configuration. The stands had a wide enough gap for me to fit the camera through. Besides looking dumb, is there any reason why I shouldn't do this?

 

[Rippie]

I used two separate stands and positioned them in the X/Y configuration. The stands had a wide enough gap for me to fit the camera through. Besides looking dumb, is there any reason why I shouldn't do this?

so you're saying the mic's were either above the camera or below it correct?
Not that you fit the camera "between" the mics, correct?

 

[Rylan Zolinski]

so you're saying the mic's were either above the camera or below it correct?
Not that you fit the camera "between" the mics, correct?

I had two stands for two mics. I made it so that the mics were in the X/Y position which worked out well. The middle of the stands were about 8 inches apart which was just enough room for me to fit my camera inbetween while be underneath the mics. I will draw a picture if that does not make sense, haha.

 

[Noiz2]

Sounds like you were between the stands and Under the mics., not between the mics. That's what was confusing people.

 

[Rylan Zolinski]

Sounds like you were between the stands and Under the mics., not between the mics. That's what was confusing people.

Yeah, this is correct. It looked goofy as hell, but at least it worked!