Shure SM58 + Feedback Destroyer = SHHHHHHHHH

[constantchaos]

So I have noticed that when my band has practice, our singer uses a Shure SM58 and a Shure 520DX Green Bullet, and the other guitarist and I use some cheaper Audio-Technica's that we got for pretty cheap at GC. We have 3 powered Behringer B212D's with 2 Feedback Destroyers (2 mic's each). All running from a Behringer 20 Channel mixer.

We've always had a problem with a very loud 'airy' type 'shhhhh' sound once the volume is turned up enough to get over the drums and guitars. Then we hooked up the 2 Audio-Technica's and once the lead mic is muted, the loud airy noise is very low and almost un-noticable. But the higher end (for tight budgets that is) SM58 still has that very annoying sound when it's not muted. Pretty sure it's not the setting on the Feedback Destroyers, but it's possible. Or maybe we can just blame it on the fact that we have mediocre Behringer products? Still doesn't explain why the lower end AT's sound better than the Shure. Any ideas?

 

[stevieb]

I own two Behringer SHARC DSP-10 Feedback destroyers, and although I like 'em for what they do, the last time I tried to use them (live situation, like you- I can not imagine using them for recording) I got a loud hiss, too- I would describe it much like you did your hiss. Can't recall what mics I was using, but I do know the hiss was the feedback destroyers. I was very disappointed- I've used them to good effect before, and didn't recall that noise before.

Really, though, the only way to find the culprit is to hook everything up in rehearsal, and then remove one component at a time, to see if it goes away or diminishes. But I would suspect the FBD's.

FBD's are cool things, but they certainly have their limitations. Perhaps the best use I ever got out of them was, once when I was setting up sound for a concert with the guys I play music with most often. I got there way early, of course, and was ringing out the system/room. One of the guys- an insufferable diva even though he has no business whatsoever acting that way- got really pissed about the "noise." I told him to take his piss-y ass outside till I was done, and I was NOT gonna go get him- he could damn well figure it out on his own.

Pissing him off was worth every penny I paid for the things...

 

[dgatwood]

Make sure you don't have the treble cranked all the way up on that channel.

Make sure the SM58 isn't taking a lot more gain than the other mics, and if it is, figure out why.

Make sure you are using the preamp gain and output gain correctly. You probably want the main fader gain to be at the unity gain mark, which is usually not all the way up on most mixers. You want to produce most of your gain with the trim pot at the top.

Finally, try a different channel on the board. It's possible that you just plain have a noisy channel.

Beyond that, check your gain staging if you have multiple devices plugged into each other. Make sure you aren't doing something like amplifying a signal, chopping it way down (by turning the output level of that device way down), and then amplifying it again.

 

[moresound]

Never used a feedback destroyer, I have EQs for that.
But If I were to use one I would put in in an insert of the monitors AUX. Not the mains , but I do know that some people do use them on mains. If that's what your doing just use the main inserts instead.