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I am planning on recording a school orchestra recital and need some help deciding on a microphone setup. I've done live sound for decades, but have done practically nothing relating to orchestral recordings. I also have a limited selection of microphones to choose from. The end result will be a stereo audio track to mix with video from multiple cameras for a concert/recital video.

My first thought would be to do a simple XY setup in the middle as high as I can get the mics. However, the last orchestra concert I filmed, the audio was being recorded by a modified decca tree configuration (not by me). That performance was also in a concert hall/theater, whereas this performance will be in a school cafeteria (lots of hard surfaces and poor acoustics as well as crowd noise, I'm sure.)

Before I get to the what would you recommend question, let me list out the microphones that I have available.
Two Audix CX111 LDC's (Cardioid)
One Audix TM1 (Omni)
Two Audio-Technica AT853 SDC's (choir/group vocal mics)(Cardioid)
Audio-Technica AE5400 Handheld LDC (Same basic capsule as the AT4050 LDC)(Cardioid)
Audio-Technica AT2020 "medium" diaphragm condenser. (Cardioid)
Various other mics that would not be useful for Orchestral stuff.

Also, everything will be tracked separately and mixed down later when I do the video editing.

So... what would you use and how would you set them up? (and why?)

1. Audix CX111's in a basic XY config?
2. Audix TM1 in the center and the CX111's spaced out in a modified Decca tree config?
3. Audix CX111's in an XY config in the center and the AT853's as outriggers spaced a ways out?
4. Some other config?



paulears Thu, 04/02/2015 - 10:33

If you are starting out, start with X/Y. Personally, recording orchestras and choirs with two microphones, direct to stereo is harder to do than a multitrack, any time! Decca Trees, and the other cleverer techniques require really good acoustics, or the results are muddy and stereo image very confused.

If you haven't seen it, the DPA microphone university pages are really helpful on the various techniques.

As somebody who has been burned doing this a few times now, one real issue is the orchestra quality in terms of musicianship. What happens is that the balance between sections is poor - sometimes dreadfully so because they have shortages in in critical areas. They may well have too many violins, too few violas, and perhaps a weak bass section - clarinets are often plentiful, but bassoons rare. A small French Horn section rarely has that rich sound, and with a rag bag of sections, a normally brilliant central mic position may emphasise the wrong things. You need to hear them, and perhaps even do a rough recording that you can take away an analyse. If you do have the imbalance, then sometimes the central position can just be moved slightly to redress the imbalance, but in worst case scenarios you may need to abandon the direct to stereo technique totally and go for section miking, perhaps to 4 channels, and then you can eq and balance in the studio, perhaps adding artificial reverb.

This is wrong from a professional viewpoint, but if the aim is to make them sound good, you might need to cheat a little. When I used to be an examiner, this kind of recording was more than often done VERY badly. In my humble view the only other technique for an amateur orchestra is M/S, as you can tweak it afterwards too.

Whatever you, concentrate on simplicity - saving the clever stuff for concert halls and nice sounding places. One tool I have always found handy is a stereoscope analyser, I quite like the one in Cubase that I've used for years. It shows you the stereo width, and it reveals all sorts of common errors - too mono, too wide, and you can even see gaps in the stereo field where there is no information. If the room has odd reflections, you can see the info clustered in certain areas. My own experiments with Decca Trees have never produced much spacial information in the rooms and spaces available to me. Don't forget that you can use these school type sessions to experiment. If their playing is a little shaky, then any inaccuracies with your stereo field won't be so obvious.

If you can record a rehearsal you will be much better prepared.

You may get advised to add 'room mics' - extra mics at the rear of the auditorium, but I've never found they really help - often wrecking the stereo field and introducing unwanted time delays.

Blumlein stereo often gets a mention, and with a lovely room, it's a nice sounding technique. In a rubbish room, it sounds very messy.

jeff92k7 Thu, 04/02/2015 - 10:55

Thanks for the response. The goal is to get a decent stereo sound of the orchestra (Middle school, so just four string sections. No winds, brass, or percussion). I want as little of the room as possible since it is a horrible, horrible sounding space. It's a cafeteria with linoleum tile floors, cinder block walls, hard tables (though they may have chairs out, not sure). At least there are terraced seating areas and a few random, low dividing walls here and there to break up the sound a little, but for all intents and purposes, it sounds a lot like a small gymnasium.

Unfortunately, I don't have four identical mics to put one on each string section. Nor would that even work because of student movement for the various combinations of performers during the event. It's multiple musical pieces performed by various combinations of students. I need to keep the mics out front and out of the way of the performers.

I have stereo on-camera mics that I will mix in during post to provide ambiance if needed, but mainly to fade in for audience applause. Regardless, as I mentioned, all mics will be multitracked separately and mixed later in post. Nothing is being mixed to stereo during the live performance.