Area mics and feedback

[hemismith]

I haven't done any theatrical stuff in quite a while, but I did an event this weekend that made me never want to do anything again. It was a show with a dozen groups each performing a short 12 minute skit. Aside from one technical rehearsal that day I wasn't familiar with any of the skits, and the performers were just regular people, not theater people. There was no budget for wireless body mics, and it wouldn't have been logistically practical anyway. So I had to use area mics.

I did a similar show a few years ago, and used boundary mics. It was difficult. On the advice of some here I tried a small diaphragm condenser for another event. It was a cardioid pattern and was difficult as well, but then I tried some super-cardioid SDC's (for yet a different event) and they were much better. So I thought I would be in good shape.

The venue was a gym with a full-size basketball court, so 60x100+ feet, with a small enclosed stage at one end, 24 feet wide by 15 feet deep. Lots of reflective surfaces except for carpet on the stage, some material on the lower half of the walls, and standard acoustic ceiling tile. I sat in the middle.

I used two mics on stands evenly spaced at the front of the stage and one mic hanging in the middle of the stage. I didn't run anything from these mics into the monitors. The main speakers were about 5 feet in front of the stage and 8-10 feet to the side, so there was more than 15 feet laterally between the front mics and mains. The mics were cheap Samson C02's and the speakers were JBLPRX612M's. In the past I've run delay speakers half-way back but I didn't think I'd need to this time.

As expected it was difficult but with a little EQ and some coaching of the performers I was able to get a good level during the tech rehearsals. But during the actual show it was horrible. I had a hard time getting a good level for anyone up that wasn't pretty close to a mic. I assume it just sounded quieter due to the audience (600+) absorbing all the sound, but it seemed that I was getting ringing/feedback earlier. I tried to only keep one mic on at a time when possible, and I had to adjust a feedback filter a little, but that didn't help a whole lot.

So first, is the feedback likely due to direct sound from the mains or reflected sound from the house? And is the biggest culprit the sound picked up from the rear/side of the mic or the sound reflected from the back of the stage? Also how much sound is typically absorbed by the audience? It seemed I needed at least a 6 db increase in level.

I thought I would have less of a problem with people in the house, so that leads me to think it was direct sound from the mains. And the mic in the middle of the stage seemed to be the most problematic, so I'm thinking it was reflected sound on the stage. (There are no rear or side curtains on this stage, just hard walls.)

But what seems most likely? What could I have done better? I could have put the mains farther to the side and a little farther forward, but I would have had to angle them inward a lot more.

Luckily this was volunteer so they couldn't and didn't complain a whole lot, but I get really discouraged with things like this.

 

[MNicolai]

You will have a bit of sound absorbed by your audience, but if anything I would expect it that to deaden the frequencies likely to cause feedback in a gymnasium. This means you have to boost the mains more, which if your microphones are close to, may create feedback.

Before you going searching for a technical explanation, consider for a moment a simpler root cause for your issues: your performers. In a tech rehearsal, there's no audience, which means no pressure. If you had just coached them beforehand, they can belt it out without much tribulation. Put an audience in front of a group of amateur performers and suddenly there's an incredible amount of pressure, and almost all of their attention is on not biffing it. This diverts all of their attention away from remembering to project their vocals and keep those gestures big so everyone in the back row can see and hear.

Short of having someone standing off to the side, reminding everyone to project all the way to the last row, there's not much you can do to cure a performer's stage fright. When I'm working with young/new performers, I like to tell them, "If you think you're being loud enough -- be louder. The person you're talking to may be standing right next to you on stage, but you should act like the people who need to hear and understand what you're saying are sitting in the back row."

It didn't sound like you were in this case, but if you're using stage monitors there's another effective way to wage psychological warfare on your performers. If they're not being loud enough, turn down their vocals in the monitors a little. Many performers, without realizing it, will begin to sing/speak louder to compensate.

 

[hemismith]

Thanks, good point, that seems highly probable. With some people it was obvious that they weren't as loud as during the rehearsal, but I didn't think about that being the case in general. Yet there were a few people that I had no trouble picking up, so I think that confirms it.

Makes me feel a little better. If I do anything similar in the future I'll try to make sure I can get more volume in rehearsal than I need so there is room to compensate during the show.

 

[museav]

Mike raises a good point and I find exactly the opposite with some bands and instrumentalists, when the room fills up they seem to almost subconsciously turn things up or play louder, as though they rather than the sound system had to compensate.