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Old September 4th, 2006, 01:02 PM   #1
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Mic placement for recording a wind band.

I would like some suggestions on how to mic a wind band (up to 75 members). I have an M/S stereo condenser mic (Studio Projects LSD 2) which works quite well, but players in the back sound distant. I have tried sm57s on either side for fills which helped somewhat. Should I place mics among the band members? If so how many and where should they be placed? Any suggestions on which mics to use? I usually have good cooperation from the conductor but sometimes it would not be possible to place mics in the band. Any suggestions for this possibility? I have a 12 channel recorder so the number of inputs is not a limitation.

Regards,
Jerry
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Old September 4th, 2006, 01:53 PM   #2
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Just a WAG (Wild-A**ed Guess) but what if you back away from the band more so there's not so much difference in distance from mic to the back row versus the mic to the front row? Let's say the group was 20 feet deep between the front row of musicians and the back - if the mic was 20 feet in front of the band, that would mean it would be twice as far to the back row as it is to the front row and that doubling means the sound is 4 times less intense for the back than it is for the front. Moving the mic back would make the difference in distance proportionally less.
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Old September 4th, 2006, 02:37 PM   #3
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That is a good idea, but often there is not room to get the mic that far away w/o actually being in the audience. Then I have the problem with picking up unwanted audio from it.

Regards,
Jerry
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Old September 4th, 2006, 05:14 PM   #4
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This is a good place for a tall mike stand. The higher you get the mic, the less obstructed sound from the back will be.

I sometimes use a "c" stand, aka century stand from the lighting & grip folks for stereo miking. An old-style atlas mic stand boom chucks in the jaws of the grip head on the c stand perfectly.

I've never measured, but I think I can get 14' high with this rig. If you're doing something like this where an audience has access you'd also want sandbags on the legs of the stand.

Or, can you fly your mic?
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Old September 4th, 2006, 08:11 PM   #5
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Jerry, there are many ways of coming at it but based on your comments, it sounds like height is the key. In a pinch, I've done full choral/orchestral jobs (and it's always the chorus paying the bill - and wanting to be heard!) with just a pair of splayed figure 8's, the key is getting them up at least 20-25'.

As I do this stuff regularly, I can think of many ways to approach it but given that you have a single coincident mic, options are limited. I would reccomend you not try to accent with cheap dynamic mics or, if you do, multitrack it so you're not locked in to the sound they will bring.

If renting is an option, consider getting a stand that'll go up at least 20' and also a good pair of omni mics (DPA or Schoeps). You can put the omnis out as flankers 10' to either side or put them on a meter bar on the main stand. One issue with any point source mic is a complete lack of phase difference. All sound arriving at the mic is doing so at the same time and the mic is creating stereo by amplitude differences. This is why the bulk of orchestral and choral recording (ensembles with many different sound sources) is done with spaced mics - often omnis. Adding the omnis would give you these time differences and really open up the sound. Also, one of the trade-offs in making a mic capsule pressure-gradient (directional) is progressively less low end pickup as the pattern tightens. So, having an MS mic with an 8 side capsule and (almost certainly) a cardiod mid cap means it's rolling off the low end. Omnis don't suffer from this and have response that goes right down, it really makes a big difference.

If you manage to get a pair of omnis but they're not as high-end as you might wish, an old trick is to mix them in with a Low-pass filter, say 100 Hz. That way, you have the low end and phase difference from the omnis added into the sound from the coincident mic. Hope it helped somewhat!

Feel free to email me offline if you wish.

Best, Scott
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Old September 5th, 2006, 01:36 AM   #6
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HI Jerry
Sounds like your using something like a HD24 using the 24/96 mode?

We have done a number of these types of recordings and have some slight variations that you might want to consider

We use a modifiied Decca Tree, like what was used in a lot of classical recordings. We hang it about 10 feet behind the conductor, and about 10 feet up but we tend to have the height adjustible so that we can make changes during rehersals to get the best pickup, We tend to find that the height is the more critical adjustment vs the distance behind the conductor.
There are a variety of mic options from the mega bucks down tothe more practical

At the lower price level we have the following


An eight foot bar, with 3 foot ends like an h with a very wide middle. In the middle we put our two mics in a co incident pair, you could use your studio projects.

At each end of the bar for an inexpensive solution you could use two oktava 012's with the OMNI capsule. As mentioned by others it is essential to use omni mics here.


If possible we will also try to hang some mics over the group using to try to pick up the rear sections also. A lot of times it depends on the group you are recording, if they are pro's and how they place the music stands, and if they are on a flat floor or if they are tiered. If you look at a lot of profesional performances you will see that the rear horns the are up higher.

I then also tend to add two room mics facing away from the performers to pick up the room sound, and carefully mix a bit of this into the mix

In essence what you have is a mic setup that is sort of surround sound.

I have found that the oktava's are small, they have a version in black these days and that sometimes you can have the stands with the performers and not be all that noticable.

It all takes a bit of experimentation and mic placement.
A lot also depends on the room you are recording in.

Sharyn
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Old September 5th, 2006, 02:00 AM   #7
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Something I've thought of doing is to attempt to get bands while practicing instead of during a live performance. If you could do that you could have unlimited options on mic placement. Audience noise wouldn't be a problem. Many bands will do a live rehearsal if they can at the place they will be playing. If you could catch that you could get a much better quality recording because you could get the best location in the room for your mic.

Remember that echoes and standing waves are always a problem in a room so picking the best spot for a mic is a matter or trial and error usually. That's how you get the best recording in a situation like this.

I always think a single stereo mic is best for recording live music. You can get the perspective the audience is supposed to get.
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Old September 5th, 2006, 04:41 AM   #8
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Quote:
Originally Posted by Scott Loiselle
J...

If renting is an option, consider getting a stand that'll go up at least 20' and also a good pair of omni mics (DPA or Schoeps). You can put the omnis out as flankers 10' to either side or put them on a meter bar on the main stand. One issue with any point source mic is a complete lack of phase difference. All sound arriving at the mic is doing so at the same time and the mic is creating stereo by amplitude differences. This is why the bulk of orchestral and choral recording (ensembles with many different sound sources) is done with spaced mics - often omnis. Adding the omnis would give you these time differences and really open up the sound. Also, one of the trade-offs in making a mic capsule pressure-gradient (directional) is progressively less low end pickup as the pattern tightens. So, having an MS mic with an 8 side capsule and (almost certainly) a cardiod mid cap means it's rolling off the low end. Omnis don't suffer from this and have response that goes right down, it really makes a big difference.
...Scott
Just bear in mind, though, that spaced omins can present problems if the resulting stereo signal is collapsed to mono, as is often the case in video.
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Old September 5th, 2006, 02:01 PM   #9
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I believe you can deal with phase cancellation in multiple omnis if you know how to use a good audio editor. Phase reversal on one (or more if more than 2 mics are used) of the mics can generally fix any problems pretty quickly I would think.
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Old September 5th, 2006, 02:42 PM   #10
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Simply reversing the phase on one spaced omni won't bring it into alignment with the other because they won't be 180-degrees out of phase to begin with. They will be partially out of phase with each other (which is the whole point of doing it that way), and the amount will vary depending on the location of any particular source in the recording space and the placement of the mics.
In addition, this problem usually shows up once the material is out of your hands, such as incorrect duplication or reproduction in mono when it was only intended to be used in stereo.
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Old September 5th, 2006, 03:10 PM   #11
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And adding to Jay, the problem is especially acute with video because a whale of a lot of video mastered in stereo gets collapsed to mono somplace along the chain to the listener's ears. There are even a number of consumer TVs that allegedly are "stereo" that are actually just a mono receiver feeding two speakers on either side of the cabinet.
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Old September 5th, 2006, 04:17 PM   #12
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The way I understand phase problems is that the sound wave is either positive or negative at any given point. When the sound wave on one mic is negative when the other side is positive you have a phase issue. If you can recognize when phase cancellation is occuring you can fix it.

Sure some frequencies may reach the different mics at opposite polarity while others don't depending on the length of the wave. But realistically problems with phase cancellation can generally be fixed by shifting the phase of one channel with an editor at the point the phase cancellation is occuring.

Moving the mics around before you get the problem is a big part of preventing the problem in the first place. But when it does occur most likely you aren't going to be hearing phase cancellation in different frequencies if you reverse phase in the sections where you have problems.

I wouldn't suggest flipping the phase of an entire channel in your editor. I would suggest only flipping it where there is a problem. It's essentially the same as flipping the phase when recording in the first place but only doing it where there is a problem. I'd say it would be pretty rare that the dominant frequencies in music we are hearing would again suffer phase cancellation in different frequencies after the phase is shifted in an editor.

It's like moving a mic to avoid problems. It will never be set perfectly but it can be set to sound it's best and that is generally good enough. Short of mic'ing each instrument in a sound booth there is really no way to ever fix the problem completely if you want to use multiple mics. We can only make it sound as good as possible. If multiple mics are needed we can only do what is possible to do and there is no way to fix the problem perfectly.
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Old September 6th, 2006, 09:02 AM   #13
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You're thinking of the relationship of the two mic signals in a moderately spaced pair much too coarsely. This isn't like using a device that's wired out of phase, creating two exactly opposite signals, or micing a snare drum from above and below simultaneously. The two signals in a spaced stereo pair will be only slightly delayed from one another, they will still both be positive-going or negative-going at the same time. Flipping the "phase-reversal" switch either in hardware or software should really be called "polarity-reversal" and it's much too coarse an adjustment to change the very slight difference in timing in a moderately spaced pair of mics.
Slipping the phase of the two tracks also isn't a good option. For one thing, "fixing" the problem would be undoing the whole reason you recorded with a spaced pair to begin with. Plus the phase relationship will change dynamically depending on the spacing of the sound generated by the ensemble in their physical arrangement. In addition, it isn't just frequency dependent. Even a single frequency from a single voice or instrument will have some comb filtering when combined to mono from a spaced pair if that sound isn't equally distant from both mics.
But again, that's why you recorded with a spaced pair to begin with, to get a slight difference in phase to enhance the stereo signal.
This shouldn't be viewed as a problem that can be "fixed", especially not with flipping a switch.
It's a decision to be made ahead of time, "do I record with a spaced pair in order to enhance the stereo recording and not worry about full mono compatibility?" or "do I achieve reasonable stereo sound with a signal that is fully mono compatible for those people in my audience who will misuse the material I'm creating after it leaves my hands?"
It's really a whole different situation from mic placement in a multi-mic setup for an original recording, even though some of the same factors come into play.

Last edited by Jay Massengill; September 6th, 2006 at 03:12 PM.
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Old September 6th, 2006, 09:37 AM   #14
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Quote:
Originally Posted by Jeff Phelps
The way I understand phase problems is that the sound wave is either positive or negative at any given point. When the sound wave on one mic is negative when the other side is positive you have a phase issue. If you can recognize when phase cancellation is occuring you can fix it. ...
Adding slightly to Jay's excellent comments. You can minimize the phase issues by insuring that the distance between the two mics in a spaced pair is at least 3 times the closest distance either mic is to the sound source. Ie - if the mics are 10 feet in front of the front row of the group they must be at least 30 feet apart to avoide phase filtering issues even in the stereo signal. After all, when you listen to the result on speakers the two channels partially mix in the air and in your ears.
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Old September 6th, 2006, 03:09 PM   #15
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Although personally I wouldn't put them that far apart for a spaced stereo recording, even though some do it that way. While the 3 to 1 rule is very important for placement of mics in a multi-mic setup, putting that much space between two mics for a spaced stereo pair would lead to a very large phase difference as well as an exaggerated stereo spread.
I'd stick with 3 to 10 feet depending on the size of the ensemble for spaced stereo, although I'd really be more likely to use a coincident or near-coincident pair because it's easier to get reliable results, especially for video work.
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