orchestra overhead feedback

[McParadigm]

Running overheads for the orchestra at my middle school, in the auditorium. I have two SM81's hanging from the ceiling, about 12 feet above the stage. I'm running them through regular mixer pres (come on, it's a middle school orchestra, it'll never sound great), out to right and left monitors.

No matter how far away I put the monitors, I cannot prevent some serious feedback. I can't get the volume up loud enough for it to matter to the audience.

?!??!

I did put an EQ into the signal path, and try locating troublesome frequencies, but there are a ton, and even the good ones start to feedback before ever getting loud enough.

 

[Waffleness]

Get yourself a graphic EQ and pull out the bad frequencies. I wouldn't be surprised if you had to pull out quite a lot, its not uncommon

 

[mattr]

If that many frequencies are 'troublesome', then they're not really troublesome are they? It just means that too much of everything is being caught in the loop, plain and simple. You'll end up EQ'ing so much you may as well just pull the faders down for the same effect.

A few things jump out at me...

I can't get the volume up loud enough for it to matter to the audience.

a) Does the orchestra even need amplifying? No orchestra I've ever played in has needed live sound reinforcement. In a large outdoor venue situation? Yes. Maybe also for a musical theatre pit band, big-band or modern jazz orchestra. I'm skeptical however whether it is actually needed for a classical orchestra in an audiitorium!

b) How loud do you want it? If you're ears aren't that well trained then you may already be getting it loud enough without realising it. The best kind of sound reinforcement is when its transparent and unnoticable - it should be a natural-sounding amplication of what is happening on stage. If you're wanting it to be loud enough to be obvious then you're probably going about this the wrong way.


So assuming you are still certain you have a problem, we continue to...

c) Mic placement. The SM81s are cardioid, meaning you should be able to quite effectively try and null the speakers to the rear. This may involve moving the mics closer to the audience/speakers, but if they are correctly positioned to take advantage of the pickup pattern then it should give better results. Also maybe try taking them off the ceiling alltogether and put them on stands at the side of the stage pointing at the orchestra and pointing away from the audience.

d) Speaker placement. Further away isn't necessarially better Where they are firing also helps - well, this goes hand-in-hand with the mic placement. How lively is the auditorium? Is sound slapping straight off the walls and back at the stage?

 

[mjbphotos]

Orchestras are set up to "push" their sound towards the audience - set up the mics on stands at the front of the stage facing the players.

 

[Simman]

The problem IMO is the mic position. Try one of these.
http://www.tape.com/resource/stereo_microphone_techniques.html

 

[SouthSIDE Glen]

Feedback is often caused by a bit too much high frequency. Have you tried just a simple roll off with the high frequency filter at the board EQ?

G.

 

[McParadigm]

Mostly, I'm there to help with some solos and softer pieces.

Here's my problem: I'm also micing the school play. Middle school kids are horrendously quiet even at their best attempts on stage, so the SM81's overhead are the best hope I have of helping them. The mics need to be out of the way and in a spot to pick up as much as possible, so they have to hand overhead. I don't have the time every day to go up, bring the mics down for the orchestra, bring them back up an hour later, rewind the cable through the rafters, and then set equipment up again.

The feedback happens with the play, too, where the volume increase is needed even more. I've identified five or 6 bands on my EQ that seem to survive increases without feedback, now.

 

[nate_dennis]

This is not so much an attempt to help solve the problem as it is an attempt to learn more. Could this feedback be created by a ground loop? I'm still trying to wrap my mind around all of this, so I'm probably WAAYYYY OFF (please don't post how much you are laughing at me, I expect that you are, but don't tell me about!! LOL) but I'm just curious. Thanks for helping me be less of an idiot.

 

[mshilarious]

This is not so much an attempt to help solve the problem as it is an attempt to learn more. Could this feedback be created by a ground loop? I'm still trying to wrap my mind around all of this, so I'm probably WAAYYYY OFF (please don't post how much you are laughing at me, I expect that you are, but don't tell me about!! LOL) but I'm just curious. Thanks for helping me be less of an idiot.

No.


OP, why does an orchestra need monitors? Put them in the mains, OK, but monitors? Eliminate those and that solves your problem.

As for plays, I would feed any cue music or something the actors need through monitors, but almost no overhead at all. And try to score a couple of wireless lapel mics, if you put them the right place on the main actors, they will pick up the lesser actors standing near them too.

You can also try hiding mics in scenery . . .

 

[Massive Master]

You can also try hiding mics in scenery . . .

Word.

I've worked and recorded... Let's just say lots (a few hundred) orchestral performances. Many youth orchestras, some real 'kids' orchestras, etc.

Don't show 'em the mics. Once they think they're in speakers, you've lost every bit of power they'd otherwise give you. Constant arguments with teachers and directors - "Oh, you need to turn them up" -- "Oh, they can't hear themselves" -- Blah, blah, blah... Once they can hear themselves, they think they're too loud. They need to *need* to hear themselves. It's the only way to get them to actually play.

 

[McParadigm]

No.


OP, why does an orchestra need monitors? Put them in the mains, OK, but monitors? Eliminate those and that solves your problem.

As for plays, I would feed any cue music or something the actors need through monitors, but almost no overhead at all. And try to score a couple of wireless lapel mics, if you put them the right place on the main actors, they will pick up the lesser actors standing near them too.

You can also try hiding mics in scenery . . .

Would that I could. I work in an inner city, fairly underfunded ms, and fixing the long-broken speaker system in the auditorium is way down on the list of priorities. So my monitors are all I've got.

Also, there's almost no scenery in this play. It's a series of skits, very minimalist in terms of props.