Feedback Destroyer (or similar)?

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punkin

punkin

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My kids have been rehearsing in a half size gymnasium. Getting ready for a summer party. They're having a rough time with feed back in the guitar amp. I've hear it for myself, when they turn the guitar amp up to a reasonable level that competes with the drums, it starts to sing.

I suspect that the acoustics of the room doesn't help. I've been doing a little web searching and I've turned up some products which look like fast tuning high-Q parametrics but they all seem to be geared towards live sound reinforcment. Can't seem to find any statements or application notes that show these units being used in an electric guitar signal path.

I'm already expecting the usual, turn it down, or sound treatment but I've got a few things working against me here; teenagers, punk/metal and the gym isn't mine. The guitar player has tried several guitars, I even loaned him one of mine tried a couple different cables (it was a stretch). Just wondering if there's a quick and easy technical solution here or not.

Thanks!

Anyone have any suggestions?
 
It might not be the amp, is the guitar player using any efx pedals? I've seen pedals cause feedback problems many times and just wonder if this might be causing the unwanted feedback. A pedal with a power boost (usualy treble) will sometimes cause some amps to feedback at even low volume, especially if combined with other pedals like overdrive and distortion. I'd say check the pedal situation, by bypassing one at a time to see if this might be the source of the problem.
 
Also you dont mention what guitar is being used, but a cheap guitar with less than quality pickups will feed back like crazy. They may simply have to turn the gain back just a touch too.
 
Are they using a PA? I'd think so and if they are, mic the guitar amp thru the PA and get the extra volume with the PA and/or monitors instead of trying to turn the guitar amp up.
 
The problem with running a feedback destroyer in a guitar rig is that the destroyer can't tell the difference between feedback and sustain. The Behringer Feedback destroyer has adjustable filters which can be used as a parametric EQ. You set them to "manual" instead of "automatic", and select the frequency and Q of each filter. Then you can boost or cut just like an EQ. You can also turn off the filters that you don't need. You could use one side of the unit for the guitar and the other side for the vocal monitors.
 
The feedback destroyers are more for overall sound reinforcement. And they do a great job. But since it's the guitar/amp, you might try playing EQ - Idealy you could use a parametric EQ and cut down on the offending frequency.

Alternatively, you could try just about any multi-frequency EQ (rack mount, floor pedal, etc.). Set it flat, let the guitar ring and then start cutting one frequency one at a time (so put the slider back up if it's not the feedback frequency.

We use a Shure unit at church connected to a PC. The Shure unit will automatically catch the bad frequency (so I don't have to guess) - then I can zero out Shure and then cut that particular frequency on the EQ.

Or as someone above stated, you use the feed back destroyer as a parametric EQ at that point.

The only issue with these auto-feedback units is that they'll keep cutting and cutting and sucking the life out of your signal. But they really excell at identifying the offending frequency and as an insurance policy that you won't blow out your speakers or ears with feedback.

Best of luck at the concert!
 
Thanks all,

No pedals/effects...that was the first thing I tried. We've also tried a couple different guitars. All had similar results.

Didn't think about the gain, I kept focusing on the guitar volume control and the amp volume control. Good call...I'll give that a go.

Also, no PA system so, it's "all band" and their gear. The bugger of it is, that they'll be having the gig in the gymnasium as part of a summer party/fund raiser for the marching band. I'm really hoping that putting some bodies in the joint will help.

I've got an old Rane PE unit. I might give it a try. Any thoughts on how best to hook this up into an amp rig? The amp does have an effects loop. I'm guessing that since it is a line level device, this might be the best place to jack it in.

Thanks a bunch all!
 
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