# feedback destroyers



## Pie4Weebl (Apr 24, 2006)

What is every ones here take on using Feedback Destroyers? I use some at my church to great effect, but when I suggested getting one to my the TD at my theatre he argued that we shouldn't because some bands have that they must be disconnected in their rider. Any arguments to counter this?

I want him to get one of these:
http://www.musiciansfriend.com/product/Live/Sound/Signal/Processors?sku=182467


----------



## koncept (Apr 24, 2006)

depending upon how you set it up you could just wire in a bypass switch (i think they all should have a bypass feautre built in). I personaly dont use them not because they are bad or do not work, but because i would rather have the full signal and eq it out. granted my high school had one...


----------



## soundman1024 (Apr 24, 2006)

Perhaps a parametric equalizer or a 1/3 octave equalizer could be used instead to EQ the feedback out. If you don't think you have the ability to EQ it out then the destroyer is probably the best approach to take.

Maybe using the destroyer as an insert on a specific problematic channel would do the job if it is only one channel giving you issues. Does anyone know if feedback destroyers work alright as an insert?


----------



## Chris15 (Apr 24, 2006)

I cannot see why a feedback destroyer would not work as an insert, after all, it is only an automatic parametric EQ.

Feedback destroyers are good when you don't have the time to properly EQ the space and in the absence of someone competent to do so.

Given the feedback about Behringer on this board, I would be hesitant to use one, but it is your decision. Shure make them also and from my experience, they are great. There are here. It appears that the Shures have a bypass function built in.


----------



## AVGuyAndy (Apr 25, 2006)

Don't waste your money, get a nice graphic EQ instead. A feedback destroyer on a band would totally kill the sound quality. If you have to have a feedback destroyer, insert it on a vocal group.


----------



## kingfisher1 (Apr 25, 2006)

considering i try and stay oblivious to sound i may be asking dumb questions....

Are these automatic parametric EQs another term for a compressor/ gate do-hickey?

i get thejist of what the do, but if someones willing to delve a bitter deeper into detail i'd would love to read it.


----------



## audioslavematt (Apr 25, 2006)

kingfisher1 said:


> considering i try and stay oblivious to sound i may be asking dumb questions....
> 
> Are these automatic parametric EQs another term for a compressor/ gate do-hickey?
> 
> i get thejist of what the do, but if someones willing to delve a bitter deeper into detail i'd would love to read it.



A compressor/gate is a completely different piece of equipment. Don't let anyone con you into believeing a compressor will eliminate feedback. It will most likely cause more problems. 

A compressor actually takes an average of a signal's strength and maintains it. If there's a gate built into the compressor as well, that's even better. The gate functions separatly from the compressor.

Basically, it automatically mutes the mic until there's enough sound to break through it. It functions by using gain reduction. (You can tell if gate is poorly set if the channels in question seem to cut in and out, even if the channel is open.) In theatre, its most useful function is as an insert into groups or the mains for wireless mics. You could also use it on area mics with very little gain reduction, although I normally don't do that. Does that sort of answer your question?


----------



## soundlight (Apr 26, 2006)

Get the DBX one. It uses the same technology that the DriveRacks use to reduce feedback. It can be found here and the notch filters on it are much narrower than the Behringer, largely eliminating unwanted signal loss with wider-band filters. The DBX one works at up to 1/80 of an octave. Plus it has 24 frequencies that it can block.

As with disconnecting, just use it as an insert to the main outs, and unplug it when someone doesn't want it.f


----------



## mbenonis (Apr 26, 2006)

audioslavematt said:


> A compressor/gate is a completely different piece of equipment. Don't let anyone con you into believing a compressor will eliminate feedback. It will most likely cause more problems.
> 
> A compressor actually takes an average of a signal's strength and maintains it. If there's a gate built into the compressor as well, that's even better. The gate functions separately from the compressor.



That's not quite right (but very close!). Compressors work by checking to see if the average (root-mean-square, to be precise, but it isn't that important) level is above a certain level. If it is above that level (called the threshold), the signal is reduced by a specified amount (called the compression ratio). For example, if I set my compressor to 3:1, for every three dB over the threshold that comes in, 1 dB comes out. A limiter works very similarly, but has a fixed ratio of infinity:1, so that the level will never pass the threshold. If the level is below the threshold, then nothing happens (unless a gate works on it).

There are other settings on a compressor such as attack and release, but those can usually be left at the default position and work fine.

As far as compressors causing problems, that can be very true, but only if it is improperly set. If your compressor is set such that it sounds good (what sounds good? That's your decision! Play around with it and see for yourself), it won't be a problem and will actually help with a feedback situation by limiting the feedback's growth.

The thing that you have to really watch out for is the gate settings. If the threshold for the gate is too high, your signal will cut out and sound really bad (just like Matt said).

Now, as far as feedback destroyers go - I personally would not recommend one unless you have no time to set up an EQ properly (as others have pointed out). They can cause random problems such as if a singer carries a sustained note for long enough, they may think that it's feedback. I would much rather have a 31-band EQ that I can use to notch out any particularly problematic feedback frequencies with.


----------



## tenor_singer (Apr 27, 2006)

Every sound engineer that I have talked with have used feedback destroyers only when time of set-up was an issue. 

In my old space we would have 2 1/2 hours after an athletic practice to set up both the FOH lights and the sound system before our "house" would open for a performance. That wasn't a lot of time to get a good EQ set up (we barely got a good gain structure set... which is why we would continually clip our system and damage our speakers in some way). The feedback destroyer was a time-saving solution.

I am now in an auditeria (picture a flat auditorium floor with lunch tables, lunch serving lines and about 65dB base level of noise because of all of the freezer compressors, pop machines, ice makers.........). We don't have to set up and tear down daily after tech rehearsals. We no longer use our feedback destroyer and really don't miss it.


----------



## Footer (Apr 28, 2006)

I have used the DBX AFS for the last 4 years and love it. It is easy to use, quick to pick up frequencies, and has 24 filters per channel. 

http://www.musiciansfriend.com/product/Live/Sound/Signal/Processors?sku=183530


----------



## avkid (Apr 28, 2006)

AVGuyAndy said:


> A feedback destroyer on a band would totally kill the sound quality. If you have to have a feedback destroyer, insert it on a vocal group.



Let me clarify that a little, a cheap feedback processor would destroy the sound of a band, or anything else for that matter.


----------



## AVGuyAndy (Apr 28, 2006)

Well, it would probably work well for speech, where there isn't much dynamic range involved.


----------



## Pie4Weebl (Apr 30, 2006)

ok, so probably not the best on foh applications, but what is the general consesus on using it for stage monitors?


----------



## audioslavematt (Apr 30, 2006)

I'm sure there are people that do, but I would never put a feedback destroyer in a monitor wedge. To me, it needs to be accurate as possible so the vocalist(s) can get a clear picture of where they are pitch wise. I work hard to EQ those wedges and I don't need a little box with knobs on it changing my EQ in the middle of the show.


----------



## AVGuyAndy (May 1, 2006)

Depends on how picky your musos are.


----------



## cutlunch (May 1, 2006)

AVGuyAndy said:


> Depends on how picky your musos are.



Aren't all muso's picky? LOL


----------



## Eboy87 (May 9, 2006)

I'd go for the 31-band EQ route. I've used the behringer unit you're talking about in church before, and hate it. This thing cut out most of the highs, and the lowest of the lows (if that made sense to anyone), and just lets the mids go, sounds real tinny coming out of the mains,

If you have the money, I'd say wait and get a dbx DriveRack. I have the DriveRack PA, and it comes in handy all the time, though I don't use the feedback destroyer in it too much, but I do like the EQ's it has in it.


----------

