My mic keeps feeding back?

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steve149 said:
I disagree .. In DJ, speaking or live situations where the possibility of no one manning the mixer at one time is there, a feedback reducer is a welcome friend. In fact, a GOOD feedback reducer will do much less impact to the overall frequency response than a 1/3 octave equalizer will, as the best will use 1/48 or 1/96 octave notch filers instead of the more broad effect of a graphic. A parametric equalizer, which has a sweepable centerpoint as well as a sweepable Q (or attenuation width) would be a better bet than a graphic.
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All of my info comes from the boss at the Concert Sound and Production company I work for.
this guy has mixed thousands of acts, from solo speakers, to 50-piece choral groups, to national rock bands!
in every kind of venue, room, and situation you can imagine.
he can name the frequency feeding back, just by hearing it...and he depends entirely on parametric EQ's to kill it.
 
Agree .. but PEQs are not quick to adjust and most people who do sound (myself included) can't identify a feedback frequency fast enough to keep it from ringing. Most concert setups have ample time to wring out the venue to pre-identify frequencies that will cause problems and then to use PEQs to take those out ahead of time. The reality of our biz is that we don't always get the time or the ability to run a system at volume long enough to do that before it happens, so you're fighting the fire as it breaks out, which usually isn't fast enough to keep it from getting out of control.

Heck, when I do live sound, I sometimes don't get enough time to even do a sound check. I'm setting levels as the band starts playing. As an MC, if you're not on the board, those feedback reducers really help out a lot, and as I said, do less damage to the sound than a graphic (GEQ) will do, assuming a decent unit.
 
Feedback eliminators and their ultra narrow notch filters can fail on many fronts. When you ring out the system you rarely have the opportunity to have the exact person who will be speaking wearing exactly what they will be wearing in exactly the same number of people in the room at exactly the same air temperature and humidity. Any change to one of those items means a slight change to the feedback frequency. If that shifts just past the edge of that narrow notch filter the feedback returns. Why is clothing on the list? Think of a hat brim reflecting directly into the microphone!

This same issue applies to the people who rely on the automated setup process of a driverack type device. Sure it flattens the response of the system in pre-event configuration, but add 200 bodies, turn up he heat 10 degrees and then check the room response. Adding to that, who says flat response is good? You typically don't want any exaggerated peaks or dips, but truly flat sound is not what most people like. Lke anything else, it's a tool that can help when used with proper knowledge.
 
But ... the alternative is what? Even a PEQ or GEQ has to be adjusted at some point. If the conditions change, you're still screwed. At least with a FBE, there is hope that the system can save you at least momentarily. Unlike a live sound setup where someone is manning the controls all the time, in a DJ/MC setup, the controls are sometimes far away .. especially when you are handing a wireless mic off to the Best Man or something. And God knows how many times I can tell someone seconds before not to do something like hold the mic to their chest, just to have them do it due to nerves or excitement.

The reality is eliminating the causes of feedback is what we strive for, but we can't always control those. Pros know how their equipment works (or should), but novices don't, so in the pass the mike setup, or in karaoke, I will still rely HEAVILY on a FBE.
 
I agree! The alternative is an educated sound person who understands all this and doesn't solely reply on a black box tool that they don't understand to solve the problems for them. :) An FBE is a great device and when used by someone who understands how it works can save many headaches. I haven't yet used one in musical setup, but in a vocal only use (especially with narrow spaced speakers or monitors for a panel of speaking participants) they are sweet!
 
I've used them for vocals and continuously reset them to eliminate any aggregate frequency removal, especially on monitors where I can't hear what's going on. I've had band members in the heat of things just grab a mic, swivel it around to "sing to the drummer" and point it right at their floor monitor .. so it even happens to the "pros".
 
steve149 said:
I've used them for vocals and continuously reset them to eliminate any aggregate frequency removal, especially on monitors where I can't hear what's going on. I've had band members in the heat of things just grab a mic, swivel it around to "sing to the drummer" and point it right at their floor monitor .. so it even happens to the "pros".
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I HATE wireless mics! The singer Saturday night walked all over the stage pointing everywhere, then came out front onto the dance floor walking right in front of the mains then back on stage and put her mic up to the drummer for him to sing (he wears a nice headset mic so this was all stage play). I just sat riding the gain on her mic only bringing it up when she had it in front of her to sing. That reminds me, I need to ask her not to do that again. :eek:
 
Learn the basics, get a copy of "Sound Reinforcement Handbook" by Gary Davis & Ralph Jones. A great reference as well as great introduction. Learn how and why as well as good engineering practices.
 
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