Hi Guys. I have only just found this web site. I am a new sound engineer. I have my first job coming up on my OWN LOL. It is a 16 day tour working 14 night. With little setup time. I am think about using a Feedback Destroyers to be on the safe side. I have to do FOH and monitor's. Would I be best using one on the hole of FOH and then one on each monitor mix?? Your suggestion's would be great Thanks Matt
Help (Feedback Destroyer)...
- Thread startersoundevo
- Start date
My experience with feedback distroyers running in auto scan mode is that as well as feedback, they destroys system response and eq.
I have found that over about a half hour or so in auto mode, the filters widen their notches, and by mid-show, the system eq is wacked.
You'll have much more success in avoiding feedback by ensuring proper system deployment. If you're doing a live band, one of the easiest ways to reduce feedback is proper monitor placement. Monitors should never directly face the back of the microphone, but rather, be placed in the null of the pickup pattern. Typically, this means 45 degrees to the back of the microphone.
All this being said, I have had quite a bit of success using the Behringer DSP1124. However, I do not run the filters in auto scan mode. I use the device as 24 channels of parametric eq (or two 12 channel parametrics) and use narrow notches to tame offending frequencies. Once you get use to how this unit operates in manual mode, ringing out the house and monitors can be done very quickly.
I have found that over about a half hour or so in auto mode, the filters widen their notches, and by mid-show, the system eq is wacked.
You'll have much more success in avoiding feedback by ensuring proper system deployment. If you're doing a live band, one of the easiest ways to reduce feedback is proper monitor placement. Monitors should never directly face the back of the microphone, but rather, be placed in the null of the pickup pattern. Typically, this means 45 degrees to the back of the microphone.
All this being said, I have had quite a bit of success using the Behringer DSP1124. However, I do not run the filters in auto scan mode. I use the device as 24 channels of parametric eq (or two 12 channel parametrics) and use narrow notches to tame offending frequencies. Once you get use to how this unit operates in manual mode, ringing out the house and monitors can be done very quickly.
bishopthomas
Well-Known Member
You're on the right track, but please do not suggest that all microphones have a supercardioid pickup pattern. The ones that do, yes, two wedges at about 45 degrees. But for cardioid mics you DO want the monitor directly at the back because that's where the null is. Check the polar diagram of the mic you're going to use to know where the null is and where best to position monitors.
Re: Help........
Do you understand the operation of a parametric eq and how to ring out a system using one? The best place would be one channel on an insert to your mains and one channel for each monitor mix.
Feedback eliminators aren't magic boxes.
Here's a typical scenario. You are using a feedback buster, and as the gig progresses, you're getting bolder and your levels are rising. Sometimes it's feedback, sometimes its a guitar tone, and your feedback buster kicks in, identifies the frequency and notches it out. You're happy. And push system harder, and your feedback buster detects another hit, and either broadens the notch on the current filter, or kicks in another one. A few hits like this and you're notching quite a few frequencies in the vox range. So, you're pushing harder, and the feedback buster is slowly but surely turning down the signal across more and more of the vocal spectrum.
Let's face it, the reason we use feedback busters is to get more gain before feedback. Additionally, there is no greater offender than vocal mics. So yea, you'll get another 3 db or so of vocal gain, but with growing notches in the response curve.
These devices are in no way fail-safe. If you're going to use one, spend a few hours with the band in practice, with the device, and intentionally get your levels up where feedback occurs, and get comfortable with the way the unit behaves. Waiting until the gig and having it on bypass until you have problems is never a good way of deploying a tool.
Do you understand the operation of a parametric eq and how to ring out a system using one? The best place would be one channel on an insert to your mains and one channel for each monitor mix.
Feedback eliminators aren't magic boxes.
Here's a typical scenario. You are using a feedback buster, and as the gig progresses, you're getting bolder and your levels are rising. Sometimes it's feedback, sometimes its a guitar tone, and your feedback buster kicks in, identifies the frequency and notches it out. You're happy. And push system harder, and your feedback buster detects another hit, and either broadens the notch on the current filter, or kicks in another one. A few hits like this and you're notching quite a few frequencies in the vox range. So, you're pushing harder, and the feedback buster is slowly but surely turning down the signal across more and more of the vocal spectrum.
Let's face it, the reason we use feedback busters is to get more gain before feedback. Additionally, there is no greater offender than vocal mics. So yea, you'll get another 3 db or so of vocal gain, but with growing notches in the response curve.
These devices are in no way fail-safe. If you're going to use one, spend a few hours with the band in practice, with the device, and intentionally get your levels up where feedback occurs, and get comfortable with the way the unit behaves. Waiting until the gig and having it on bypass until you have problems is never a good way of deploying a tool.
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The original theory and intent behind feedback destroyers was...reasonable. They were a string of very steep sloped filters (thus the term notch filter) that a computer could insert on an offending frequency. One main benefit being that the computer could recognize and automatically deal with a problem faster than any human operator. Another benefit was that the slopes of the filters were much steeper than what is commonly available on most EQs, thus an offending frequency could be notched out without affecting surrounding frequencies as much. Back when I was doing instals, I had a couple venues where we used Sabine FBX units in permanent installs in live rooms to gain a couple db of headroom before feedback. At the time, those units could lock in most of their filters and only had the processing power to have 1 or 2 "floating" filters. Worked well.
With the increase in technology and processing power over the last few years, multiple bands of parameteric EQ, measurement software, and generally more knowledge about how sound behaves allows the sound tech tools to make smarter decisions about deploying and optimizing the rig. This means we can deploy our rigs better and reduce feedback potential, and we have better tools to deal with problems that deployment can't. What was being done "automatically" for us before by generic computer algorithms, is now in our hands to deal with in a way that is specific to a given situation. I find myself loathe to return that control to a "black box" to do my thinking for me. I'm not saying that there may not be an application for them, as I have a pair and even used them oncor twice, but they are a tool and as such should only be used for the job they are designed for, not as a crutch, or a way to avoid learning how to buy or use an EQ, or a band-aide for a poorly deployed system.
Rather than a Feedback desroyer, take heed to advice in this thread about mic placement, and get more info about speakers placement and good EQ practices.
Matt
bishopthomas
Well-Known Member
I would not use a feedback destroyer on the overall mix for a live band, if you want it as a 'safety' then insert it on individual channels.
Another consideration is what you have for system EQ. Most 'feedback destroyer' units let you assign filters as automatic or fixed and using one for some fixed, narrow band filtering might be useful if all you have otherwise is an octave or 2/3 octave graphic EQ.
On the mic and monitor placement, your singers must be much more static than some of the ones I've worked with. Sometimes the mic is going to end up pointed in just about every direction, in which case not having the back lobe of a super/hyper may help. But when the singer steps forward and cups the mic while standing on the monitor, all bets are off.
Another consideration is what you have for system EQ. Most 'feedback destroyer' units let you assign filters as automatic or fixed and using one for some fixed, narrow band filtering might be useful if all you have otherwise is an octave or 2/3 octave graphic EQ.
On the mic and monitor placement, your singers must be much more static than some of the ones I've worked with. Sometimes the mic is going to end up pointed in just about every direction, in which case not having the back lobe of a super/hyper may help. But when the singer steps forward and cups the mic while standing on the monitor, all bets are off.
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