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We closed off one section of the bar and changed the room around a bit. The acoustics of it have certainly changed; wood in the corner behind the singer with he singer further into that corner. As a result I have been getting feedback on new frequencies and can't seem to kill them all off.

I am toying with the idea of a feedback destroyer. I am pretty sure I can EQ out the mains if I take the time but I am concerned about setting up a separate EQ for the monitor. I have two questions for those in the know:

1) What have you used and your experiences (DBX, Sabine, Berhinger)

2) Can the signal path be Mic - >feedback suppression > Preamp -> Board ->out to main or monitor? I want to use a single unit to kill feedback from the room and if I get any from the monitor but I do not run the monitor and mains from the same control.

Thanks!

The closest I've come is in one of our monitor rigs we have some older RANE 31-band EQ's that have level lights on each band. So when one starts feeding back you'll see it push the level into the red which makes it easy to find quick and pull back. Kind of a cool tool but I don't usually rely much on those lights.

In most cases I find that being able to determine what frequency is feeding back by ear is far more effective. Harmonics can play funny tricks on the hardware when feedback starts ringing and unless you can discern with your ear what frequency it actually is that's giving you problems, you still end up hunting for the right slider. I always recommend to people that they practice ringing out monitors on a regular basis in order to develop an ear for what the different frequencies sound like.

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DJ Tony
Let It Rip Karaoke

The Behringer FBD is completely useless. It tends to continue taking frequencies out that aren't really feeding back, but getting hot. I have used the Sabine years ago & it worked well but if you have a good 31 band eq & likes stated being able to determine which frequencies are the problems, you can usually fix it quickly.

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LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

Alright, good EQ and good ear are better. Now my question is where that good EQ should go in the signal chain. I run the monitor out of the board on a separately from the mains. I currently EQ out the mains and have had good success with the sound. I'd like to run something that can EQ out the mics before the board so it'll handle feedback for the mains and the monitor. Is that possible? Is it not recommended?

What I'm really looking to do is use one piece of equipment instead of buying a second piece. If I need two, well, I need two. But I value hearing the opinions of others who are more sound engineer then I am. I'm more of a personality who learns sound because he has to. Every time I reach a goal in room sound I start to hear things I want to fix. I'd like to think it's because I'm learning and not because I'm just that impossible to satisfy

Umm, one piece probably won't do it. I say that cause in a bar situation you have all kinds of other electrical interference. I know of one KJ that try's to run speakers, monitor, 2 screens and all his other stuff off one and then wonders why he can't dial in the mics and gets squeels all the time. The only reason we still go to this one is cause of the bartenders. Seriously if the current bartenders left we would not go at all. My husband has been trying to give little pieces of advice to the guy to try and help him since he already knows that Thom has done KJ, DJ and band stuff before. A little at a time and the guy is getting better.

If you have an eq on the mains already, you may consider a single channel for the monitor. dbx 131 is what I use & it works great.

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LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

For its intended purpose of automatically eliminating feedback, I totally agree. ALL these tools are just bad guessing machines.


This is not the cause of feedback. Perhaps you are describing "mains hum?" Feedback, by definition, is the microphone picking up frequency response peaks from the loudspeakers and amplifying them, which the microphone again picks up at a louder level, sends back to the loudspeakers, etc. until it gets louder and louder.

Not saying that KJ isn't an idiot, but the electrical sillyness does not cause his feedback, his inability to deploy his PA system and microphones appropriately for the space and needed gain-before-feedback is the cause.

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Jeff Wheeler, moonlight DJ/KJ

I do have to take back the 'completely' useless statement, I did use it in my home studio as a parametric eq only & it did ok in that respect.

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LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

Yeah that's why I qualified my statement in more detail, but obviously the OP, and 99% of other users who consider buying the device, want it to do the thing that we agree it is useless at doing. Worse than useless, really, since it cuts good signal too.

I am not sure what to do with mine now. I have parametric EQ on all my mix sends. I was thinking about selling it.

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Jeff Wheeler, moonlight DJ/KJ

By "electrical interference" is trying to put too much on one thing. If you are plugging into the same place as other things you could get interference from what is there. At least that is what the electrical engineers that I know tell me. That is why they tell you not to use too many power strips. Having too many things on one thing can backfire and cause all kinds of problems.

You'll typically trip a breaker if you do that. The #1 power related sound issue is improper grounding that causes a hum on the line. I'm not experienceing that, I'm experiencing feedback when I really have to run the gain up on a someone who is whispering into the mic.

<sigh> Looks like I EQ it out. No easy way around it. I just wish I had more know how but I guess experience is the best teacher.

But that is not going to cause 'feedback'. It may cause a low frequency electrical hum due to possible bad grounding within the building or in the sound system or other possible electrical interference - but that is not feedback - which is sound being fed into a speaker & reamplified causing low or high pitch squeals.

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LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

Best way to start is on a time when you have a chance, flat line everything eq wise (on the mixer, any external eq & any eq processor like a BBE or Aphex) - set it all to middle (0) position. Turn up the mains until you just start to hear a feedback frequency, go to you eq, pull down each slider one at a time - if it does not decrease or stop the frequeny, bring it back up to the middle position and move to the next until you find it. Once you find the offending frequency, turn it down until it stops, then bump the 2 sliders on each side down about one notch. Turn the main volume up a little more until you hear the next feedback, do the same. Repeat maybe 1 or 2 more times, then you should be ok for the night.

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LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

Thanks Lonman. That's how I'd done it before but the room changed and I added a sub. That seems to have thrown it out of whack and well, I was looking for a shortcut to fix it <hangs head>.

Nope, if you change speaker positions and add a sub, you would just need to re-ring out the system as if you were starting from scratch.

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I eliminated mic feedback after I added the DBX Drive Rack PX on my powered active speakers & sub. I can now hear my soft singers when I put them on a higher mic gain. My EQ is also on the higher range thus great improvement in sound.

Placement of speakers are now facing the audience as opposed to facing both walls sideways. One of the best unit performer I ever bought. Check it out guys. DBX Drive Rack PA for non powered speakers. Piece of advice - don't use the unit auto EQ.

Rereading this brings me to something I missed in your post earlier Lonman.

From what I read you bring the volume up on the mains and get the feedback to hover and then play with the EQ to eliminate it.

What I have been doing is bringing the gain up on one of the mics until I got some feedback, noted the frequency on the RTA and brought that frequency down. My biggest problem with the method I have used is getting the feedback to hover around and then hear it disappear. I normally get an ever increasing squeal while I watch what part of the spectrum climbed off and have to pull the gain down.

Do you set the gain on the mics up then increase the volume? Or do you leave the mic gain set to the normal gain structure?

I only have opportunity to wring things out infrequently since the bar typically has folks in it but I'll try the method you suggest next time I can.

Typically you'll set the mics eq to zero. Set the mics faders & gain up to where it just starts to blink, then drop the gain down a tad. Then you work the main up until you hear the feedback (eq should be set flatline to start as well - also any other eq processors ie BBE/Aural Exciters, etc should be bypassed), then find the frequency that is causing problems & drop it down to where it stops, then drop the 2 adjacent frequecnies down a little. Repeat that process3 or 4 times until you get the main volume to the point you'd normally run it. Now you can re-engage any other processors & adjust the mic eq as needed & you should have minimal problems.

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You mention an EQ for the mics. Do you have an EQ between the mics and the preamp? If the preamp is in the board (like min) do you have it as in insert between the pre-amp and the gain?

My current setup is:

Mic receiver/wired mic ->Board (compression/FX) -> EQ -> sound reinforcement (I have both passive and active speakers)

Ideally I'd like to run like this:

Mic receiver/wired mic -> EQ -> board (compression/FX) -> sound reinforcement

Turning off processing on the board is easy, no worries there. Right now I'm notching the main mix for feedback but I'd like to keep the eq from killing frequencies that you should hear in the music. I'm just looking at the problem from my perspective. The mics are feeding back frequencies. Dampen them from the mic.

If that is faulty thinking that's fine, lemme know

The mic should go through the pre-amp first. Your wireless mic receiver probably puts out a line-level signal, so it could connect directly to an equalizer; but the wired mic will need to go into the mixer.

If your mixer has INSERT I/O jacks on the channels, you can connect an equalizer to a channel via that jack, just like you would an outboard compressor.


Honestly, at this level, if you are inserting equalizers on your channels, you should probably just buy a better mixer that has decent EQ.

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Jeff Wheeler, moonlight DJ/KJ