EQ and the Feedback Monster. Help!

Hey CB, first time poster, long, LONG time reader, so be easy on me!

I am the selected Sound Designer and Board Operator for a showing of Legally Blonde. We are running 24 Wireless Microphones in a very tiny, cramped black box theatre, and we have always had to battle feedback issues. We seat about 150 people, the playing space is largely a 20x20 platform in the middle, and the six speakers hang directly above it pointing around to the audience, which is situated in a U shape around the platform.

How can I defeat the feedback monster here, and keep the sound, well, good? We run with an LS9, a board that I am very accustomed to, but EQ and I have never really gotten along. I find that, even though I EQ one microphone and get it sounding great, as soon as I throw in another, or god forbid we add the orchestra, feedback occurs.

What can I do (besides moving the speakers) to fix this issue?

I'd greatly appreciate any links to other media or documents I could read that may help me understand it better as well. Thank you!

K
 
Are wireless required for a space this small?
 
Yes - however, only for musicals. We use a full band, although they are situated slightly sunken into the shop doors, and most, if not all, of the sound we get is natural - not mic'ed. However, because of this, we have to use mic's. Its also a situation where we just can't always isolate the band due to building constraints. So, yes, in this space and with musicals, we always run mics. And it almost always sounds bad. I'm hoping to change that.

I'm going to take another stab at using the graphic EQ on the LS9 to go through and EQ everything across the board, I just feel like once i then EQ every individual microphone, it won't matter.
 
I'm going to take another stab at using the graphic EQ on the LS9 to go through and EQ everything across the board, I just feel like once i then EQ every individual microphone, it won't matter.
I have to start with whether you really need 24 wireless microphones for a 20'x20' stage (which is 16.67 square feet per microphone if you look at it that way).

EQ is probably not going to be that effective. You might be able to eliminate some problem frequencies common to the microphones and/or speakers themselves but every time someone with an open mic moves the relationship of that microphone to the speakers, other microphones and even other 'talkers' will change, potentially affecting the levels and/or frequencies related to feedback.

Probably the most effective concepts are 1) minimize the number of open microphones, 2) get the microphones as close as possible to the actor's mouths, 3) keep as much of the the energy of the speakers as possible aimed at the listeners and as little as possible directed at the stage and 4) consider how the mic patterns and speaker patterns relate (i.e. can you get the speakers in the nulls of the mic patterns and/or the mics at better points in the speaker pattern).

If your system and the blocking and movement allow you might want to consider some form of zoned microphones, for example an actor to one side of the stage may not need to be in the speakers covering the audience on the same side as much, if at all in a small room.
 
Kyle,

Is there any way you can upload some pics of the performance space - especially how the loudspeakers are setup in the space in relation to the stage and audience areas? That would be most helpful.

Also, an accurate description of the system's components from microphone (input device) to loudspeaker (output device) and everything piece of gear in-between is good to have...
 
What part of Michigan are you from? If you are at all local to me, I might be able to offer more assistance to you, or know of someone in your area.

~Dave
 
Mutliple mics in a musical, with a band, in a small space is always going to be a challenge! :confused:

If you can get it sounding good with a single person on a mic singing along to the band then you have hope, if not then you have to take it back to the basics and work out what's wrong. It may just be that you're in the wrong room and the band are too darn loud (the most common problem !).
Unfortunately in the middle of a production run is a bit late to try and resolve the issue of wrong place.

An easy way to tell if the band are too loud at the singing position is to stand there next to the singer while rehearsal is happpening and listen to the band level versus the singers acoustic/unamplified level. If you can hear more band than singer then they're too loud.

A mic can't determine which signal to boost; loudest sound to the mic wins, and if the band are loud then the mic will be picking up both singer & band. Then when you try & boost the singer(s) to get them over the level of the band, you also boost the bands level. This ends in volume wars, and you keep pushing the singers mic louder and as you're hearing, get feedback.

Here are a couple of relevant threads for reading that may assist you.

http://www.controlbooth.com/forums/sound-music-intercom/26334-ringing-out-equalizing-foh-onstage-monitors.html?highlight=#post233251

http://www.controlbooth.com/forums/sound-music-intercom/29066-childrens-musical-sound-design.html#post258310

I hope this helps!
 
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I'd use parametric EQ before the graphics.

If you set up one or more buses as groups (male & female is common, or primaries and secondaries), you'll have four bands plus HPF. You can also insert a graphic in each group. Then of course worst case you have more parametric in the L/R as well.

Any time you use graphics, owing to the wide filters you soon run into "attenuation by equalization". This can happen with parametrics as well.
 
I use a space a little smaller than this, 100 seats, with at most 20 mics. Along with 4 hanging for chorus.It can't be too loud in there since it is a small space. And depending on the size of your speakers, 6 seams to be a little excessive. They way I use mics is just so songs, if needed, depending on size of the band. If you have a 12 piece, then maybe more, but with a 3 piece band, then yea a little less. I think there is a bigger problem here then EQ. Try turning down the gain on everything, that could be. try panning the band only to the other side (if the band is on one side, instead of the middle), thats less open mics. Also just have to be on top of the faders. Ride those faders all night baby!
 

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