The answer to your question depends upon several factors. One of the key considerations is the type of program (rock concert, orchestra concert, choir concert, play, musical?) and how the visibility of the microphones affects the aesthetics of the stage. A secondary concern is the type of sound system arrangement you have and whether it is prone to feed-back (squealing) or not.
'Stage Mics' are typically something like the AKG (formerly Crown) PCC-160 or Bartlett Audio Stage Floor Mic, and can do well for large groups of performers and well-blocked scenes with smaller groups. They can also be hidden on tables, on the back of posts and props, and in the ceiling of set piece overhangs (inner below).
Hanging Mics are typically something like the Audax ADX40 or the Audio Technica 853AU, and can also do well if they are close enough to the performers. Where the floor mics are about 60" (vertically) from the performer's head, to get the same effect you need to hang the overhead mics low, about 60" above the performer's heads. This makes them very visible (about 10' above the floor). As the microphones are raised further, they offer less gain before feedback.
A third alternative that works well for orchestra an choral concerts is to use 'stick mics' like the Ace Backstage CSM series.
In general, you want to use cardioid or hypercardioid pick-up patterns for overhead mics. Hanging mics tend to want to twist and re-aim themselves at the most inopportune times, so keeping them aimed towards the performers is typically achieved by tying them back to a piece if scenery or an batten further upstage with some very fine black monofilament line.
Performer blocking is important. If the performer's mouth does not have a direct line-of-sight to the microphone, then the sound will be attenuated and muffled.
With any microphone arrangement, it is typically necessary to 'ride gain' continuously so that the microphones that are not in use are attenuated 10-15 dB when not need. The fewer open mics that are active at one time reduces the likelihood of feedback occurring. If you are using a digital audio mixing console you may be able to save the scene-to-scene levels as cues to help automate the changes.
Also, the 'hollowness' that is common when using microphones onstage can be helped if you are using a digital type audio mixing console that has delay settings for the individual microphone channels. An article about this can be found here.
Filter out the unnecessary sound. Voices have very little sound below 100Hz or above 8KHz. Filtering off these parts of the microphone pick-up will affect the sound very little and can eliminate footfall sounds and squeaky noises. Learn to use your High Pass (Low Cut) and Low Pass (High Cut) controls.
Another alternative to fixing the gain-before-feedback issue doesn't involve the microphones at all. This would be using a loudspeaker system that contributes less correlated sound back into the microphones. Many sound system loudspeaker arrays (clusters or line arrays) spill sound back to the stage in a manner that stimulates the feedback. There are several ways to correct this:
- Replace the speakers with highly directional arrays.
- Replace the speakers with a DML type speaker like the Tectonic Audio Labs PL-11.
- Relocate or Re-aim the speakers to reduce sound spill onto the stage.
Note: The work rigging speakers should be left to qualified riggers as these are heavy devices that are hanging over people's heads. The design sound systems involves more than just buying speakers - we highly recommend that a school seek out a sound system design consultant so that you get an objective qualified design that can be put out for bid proposals by multiple contractors.
There are also hardware and software tools that create very narrow 'anti-feedback' notch filters to reduce the onset of feedback. These don't work well on an mix of all the microphones, but can be helpful if applied to each individual microphone. The downside of the anti-feedback filters is that they frequently create very audible changes to the sound.
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Erich Friend
Theatre Consultant
Teqniqal Systems
Original Message:
Sent: 11-01-2015 09:40
From: Brian Getz
Subject: Mics
Stage mics or hanging mics for a high school auditorium, thoughts?
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Brian Getz
Smithsburg MD
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