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[Jim Thorn]

I'm a sound system maintenance tech in a large school system, and I often have to warn teachers looking to upgrade their stage sound systems that overhead microphones, while helping somewhat, will never give them the "in your face" sound that close-miking will.  They've just never had to think about the physics of it.  One of my Junior High drama teachers told me that a school where she previously worked had a pair of shotgun mics mounted on the ceiling of the cafeteria, near the center of the track lights, twenty or thirty feet out on the audience side of the curtain.  She said that they did a good job of picking up action anywhere on the stage, and feedback was not a problem.

Have any of you worked with such a setup?  As I've looked at information on shotguns, I've found that very few of them show actual polar plots, so it's hard to predict which ones would be good candidates, and the prices are all over the map!  I'd like to take advantage of somebody else's good experience as my starting point if I recommend that we try shotguns on an upcoming renovation.

I tried contacting the maintenance people at the school she referred to, but alas -- the maintenance folks who are there now don't know anything about it, and don't care to know anything.

Can anyone steer me toward a setup they know to be practical?

Jim Thorn

[Lee Buckalew]

Jim,
The same laws of physics apply.  The inverse square law just does not allow for use such as this teacher is describing to you.
There is no way that two shotgun mics, mounted 30' from actors, especially high school actors (or any other untrained voices) will pick up voices and amplify them effectively.
If, at 30' away, the voices are not loud enough and they need to be amplified, there is no way for the mics to selectively amplify just the voice.  They will amplify everything that they are picking up.

The only mic layout, for distance micing, that can help for voice like this would be a parabolic reflector type mic but these have to be focused at the wanted sound source.

Rather than trying shotguns during a renovation, you should be able to demo some from a local supplier or a local designer if you have a good relationship with them.

Lee Buckalew
Pro Sound Advice, Inc.

[Brad Weber]

One of my Junior High drama teachers told me that a school where she previously worked had a pair of shotgun mics mounted on the ceiling of the cafeteria, near the center of the track lights, twenty or thirty feet out on the audience side of the curtain.  She said that they did a good job of picking up action anywhere on the stage, and feedback was not a problem.

A "good job" is quite subjective and that was in that specific situation.  How well do both the application and expected results translate to other situation?  For example, Lee made a good point about the mics only being able to pick up what sound hits them, just how much of the sound system the mics also pick up and how that relates to gain before feedback could be very dependent upon the specifics of the venue.

In addition, look at the polars you can find for shotguns and note how many have a large back lobe.  When mounted at the ceiling that can lead to picking up diffuser, ballast and projector noise.  Also notice how many of the mics may start to lose pattern control at lower frequencies, being 20'-30' from the stage and probably closer than that to the audience, guess what that means in terms of picking up sounds other than those on stage?

The point is that while shotgun mics may work, that could depend greatly on the specific situation and would need to be assessed on a case-by-case basis.

[Jim Thorn]

A "good job" is quite subjective and that was in that specific situation.  How well do both the application and expected results translate to other situation?  For example, Lee made a good point about the mics only being able to pick up what sound hits them, just how much of the sound system the mics also pick up and how that relates to gain before feedback could be very dependent upon the specifics of the venue.

In addition, look at the polars you can find for shotguns and note how many have a large back lobe.  When mounted at the ceiling that can lead to picking up diffuser, ballast and projector noise.  Also notice how many of the mics may start to lose pattern control at lower frequencies, being 20'-30' from the stage and probably closer than that to the audience, guess what that means in terms of picking up sounds other than those on stage?

You make a good point about the back lobe.  As far as loss of low frequency pattern control, we're mostly just looking for voice range for dialog, so I think it could be rolled off.  If they're serious about singing on stage, they'd roll in the choir's portable system.  The drama teacher who had a shotgun setup has heard our best attempts at overheads for use by untrained staff, and she felt the shotguns worked better. 

The point is that while shotgun mics may work, that could depend greatly on the specific situation and would need to be assessed on a case-by-case basis.

Agreed.  With an awareness of the possible snags, I would still love to hear from someone who has tried a similar setup.  The suggestion to try to audition something may be my best shot at hearing for myself how well they might do.

Since the systems are generally TOA inwall amps with 12 to 20 coaxial ceiling speakers in a cafeteria, the ease of use for unskilled operators is a large factor.

Thanks for your comments!

Jim Thorn

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