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Unread 08-18-2016, 11:13 PM   #1
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Vocalist positioning relative to mains, feedback, and solutions?

Our stage at church has a pull-out section that can extend the front out about eight feet. This is great for dispersing musicians and singers across a wider area, but is evidently not something that was thought out from a live-sound perspective at all. The mains are mounted directly above the edge of the main stage, so when singers are out on the extended platform they're actually standing in front of the overhead speakers. Or, to put it more from an audio engineer's perspective, the microphones are put in front of the house mains.

This leads to one very frustrating phenomenon: feedback. It's not as bad if I dull down the 4khz+ range in the EQ for a vocal mic, but then a lot of crispness and clarity is lost. Our piano player tonight insisted that we move the keyboard down onto the extension platform, so that she could "be farther away from the drums." I tried explaining to them that this would make mic feedback more likely and would make it more difficult for me as an engineer to maintain a great, crisp sound with ample house volume. Her response was, "I'll just have to practice more," so maybe she just didn't understand what I was trying to get at. This bit is still easy enough for me to work around, but the biggest frustration is that preachers tend to like to walk the edge of the stage, which puts them right in the "feedback zone" with the mains (and, unfortunately, the only way to prevent feedback is to cut the frequencies that do feed back, which makes the speaker's voice sound terrible).

Apparently people have tried moving the stage extension back before, and compensating by moving the chairs closer to the stage, but from what I've told, people just end up sitting further back anyway, so it creates an awkward gap between the congregation and the singers. So I'm left with a predicament... And a few options to this:

Option 1: Buy a Feedback Destroyer for the house mains. About $300. Looking at this, as it could make things a little more interesting than simply cutting down on feedback, though this is probably a better candidate.

Option 2: Move the stage back. Get a drum mic kit and a shield (which is part of "future plans" for the setup as is, but maybe just moving the stage back and explaining to people that they're going to have to deal with a bit of noise crowding for the time being. Definitely going to make some people unhappy. Probably not going to work until the shield and kit mics are in the mix.

Option 3: Suppress the 4khz+ range on all the vocal mics so that a) the mics in front of the mains don't feed back and b) the ones behind the mains don't sound out-of-place in being brighter than the other mics.

Maybe playing around with some graphic EQ plugins could help me dampen some of those feedback frequencies, especially in the 4khz+ range, but I'm kind of curious if anyone else here has encountered a similar situation where mics were in front of speakers and EQing needed to be controlled a little more carefully?

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Unread 08-19-2016, 11:04 AM   #2
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hi... a few thoughts...

- what kind of mics are your preachers and other speakers using? headset boom mics should get rid of feedback for them. And for the piano player, if she sings.

- drum shields don't work unless they are fully enclosed (which always looks odd to me). If you don't add a lid and/or totally surround the kit then it will only be s good as the absorbtion of the back wall.

- I don't know about plugins but in analogue world, where I live, a 31-band graphic has got to help

- if you can't move the main speakers (why not?) can you adjust their angle?

No doubt others will have better suggestions! I hope you get to the bottom of this...
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Unread 08-25-2016, 02:52 PM   #3
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I never use "Feedback Eliminators" because they ignore the underlying issue, which is usually speaker placement, but sometimes can also be mic selection, and mic placement.

The problem, even with the most advanced units, is they can mistake any single sustained note (ebow, anyone? though I've heard it happen with piano as well) for feedback, and try to notch it out. This lowers overall system gain, so the tendency is to turn up to compensate for the lost volume, which then causes more notching, which causes you to need more gain . . . you see where this goes.

I would seriously look at options for changing the speaker placement.

Can you post a couple of pics of the room from the front and from the back to get more of an idea of the challenges?
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Unread 01-05-2017, 08:08 PM   #4
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After a few months I think I've solved this issue. At least, I haven't had any feedback in quite a while. Which is odd, considering since August I've managed to make the monitors louder on stage, as well as making the mains louder. It was probably EQing of monitors + better EQ control over channels. A touch of PEQ here and there to cut out a feedback frequency really does do wonders. I don't think we'll be needing a feedback destroyer yet. The only channel I'm still having feedback issues with is our lapel mic; no matter what EQ tricks I use on it, it always feeds back once it kicks over a certain level (which is rather irksome). But I think I have it at a point where it'll be mostly okay moving forward.
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Unread 01-30-2017, 04:18 PM   #5
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I haven't had any feedback in quite a while. Which is odd, considering since August I've managed to make the monitors louder on stage, as well as making the mains louder.
You know when I usually hear this sentence almost verbatim?

Right before people find out all their high frequency drivers on all their speakers are fried.

High frequency feedback is the biggest tweeter killer known.

Not saying yours are, but might be worth checking.
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Unread 03-14-2017, 09:02 AM   #6
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Quote:
Originally Posted by Maestro_dmc View Post

You know when I usually hear this sentence almost verbatim?

Right before people find out all their high frequency drivers on all their speakers are fried.

High frequency feedback is the biggest tweeter killer known.

Not saying yours are, but might be worth checking.
I think the biggest thing that's helped is utilizing cuts in the lower frequencies instead of boosting the high frequencies. Also the vocalists have all been moved back about 4-8 feet (depending on the week) which helps quite a bit.

I don't suspect the tweeters would be damaged at all. They handle high frequencies like a charm and I haven't noticed any distortion or abnormalities in the sound. I think just learning how to handle the EQing relative to the room has helped a lot.
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