Feedback Suppressor

[jack hale]

hi guy's just wondering if anyone has had experience with Feedback Suppressors are they any good would it replace a graphic eq if not would it go in the chain before or after the eq? douse it effect the sound drastically or is it not noticeable? how douse it work? douse it just keep everything in check or is it a lazy mans way out? if they are worth picking up what brand and price range would you recommend I have been looking at a DBX AFS224 Feedback Suppressor

thack's

jack

[mervaka]

Suppressors keeps the stoopid people stoopid. In the right hands, a 31 band GEQ will do the job far better.

[dbuckley]

Feedback supressors are a tool, just like a 31 band graphic. In the right hands, they do an excellent job. What they aren't are black magic, or fit and forget. And if you do fir and forget and leave them in full auto mode, you will get nasty surprises. And with many types of surpressors, you dont get the warning hollow ringy stuff before feedback sets in; the systemn just goes into full howl, so dynamic control to prevcent damage to ears and/or system is highly recommended.

 

The majority of audio professionals (see comment above, I'm surprised thre aren't more) just dismiss these tools out of hand, but rarely from personal experience.

[Original Beef]

Feedback suppressors use notch filters approx 1/60th of an octave wide so don't take out huge chunks of the audio spectrum like graphic eq's which can be like using a sledgehammer to crack a nut. I certainly don't think you are stoopid (sic) by using them as they are a very useful audio tool that can be used with or without graphic eq's. I use them in tricky environments such as when using hung microphones, or other occasions when I have to distant mic and estimate they give me approximately 3-6db more gain before feedback.

 

I have no experience with the DBX per se, but it is a decent mid priced brand so should be ok in my opinion.

[jack hale]

Feedback suppressors use notch filters approx 1/60th of an octave wide so don't take out huge chunks of the audio spectrum like graphic eq's which can be like using a sledgehammer to crack a nut. I certainly don't think you are stoopid (sic) by using them as they are a very useful audio tool that can be used with or without graphic eq's. I use them in tricky environments such as when using hung microphones, or other occasions when I have to distant mic and estimate they give me approximately 3-6db more gain before feedback.

 

I have no experience with the DBX per se, but it is a decent mid priced brand so should be ok in my opinion.

 

witch brand do you use?

[mallyJJ87]

I remember using a Behringer feedback destroyer pro about 6 years ago (when I was a keen teenager technician), which back then was about £200 (I think) but haven't used one since . As has already been said, I doubt it could replace a graphic EQ: not sure how you'd go about system optimisation without a graphic :blink:  

[Simon Lewis]

I've used the (sadly discontinued) Shure DFR11EQ and still have one or two in use. They are accurate, sound good and behave themselves. I've also used the Behringer Shark, and would say pretty much the opposite.

Feedback reducers seem to be a product that are of use to the person who knows what they are doing with it and are prepared to pay for a good, well designed unit.

 

Simon

[S&L]

I've used the (sadly discontinued) Shure DFR11EQ and still have one or two in use. They are accurate, sound good and behave themselves. I've also used the Behringer Shark, and would say pretty much the opposite.

Feedback reducers seem to be a product that are of use to the person who knows what they are doing with it and are prepared to pay for a good, well designed unit.

 

Simon

 

ditto for the shark - it works ok but the time you spend learning it would be better spent with a graphic or at least I have found it to be the case. I have a shark that tends to sit on a shelf and rarely goes out live anymore - it's a pain especially for compressed set up's - the FBQ graphics on the other hand have been really useful in training my ears to where the feedback frequencies are and are fast and intuitive to operate

[dbuckley]

The problem with the traditional graphic is that it is a blunt instrument. Having "just" 31 bands to grab for (and using the well-calibrated ear to know just which band to grab) makes for a livable life on monitor duty. Having hundreds of sliders would (apart from needing a 60 inch wide rack!) maker it really hard to grab the right slider first time. 31 bands is a workable compromise.

 

For front of house feedback reduction, a 31 band EQ is a bad tool as it rips out a whole third of an octave in one go. Thats an acceptable compromise on monitors, but not for FOH. The advantage that feedback eliminators have is that they can have a very narrow to precisely reduce a specific narrow range of frequencies. They are, in reality an automatic parametric equaliser. A parametric is a much better tool for fixing FOH tendencies to feedback.

 

The shark is a mixed bag. I have a couple so I've played with them a lot. If you link both together in series(!) you get many "bands" of howl reduction. You can push your fader up many, many dB and make the system almost impossible to howl. But it sounds absolutely crap. Its cut everything in the goal of feedback reduction, leaving no audio left to hear!!!!! Use just a few bands (say 5) and let it deal with the worst excesses, and you are onto a much better result. But a manually tuned parametric does a better job if you have the time required to set it up. What five bands of shark will do automatically in a couple of seconds can take many minutes on the parametric (ie doing as little as possible), and sound no better.

 

So, retire the Shark from feedback elimination duties, and get something better like a Sabine. Which is not a cheap tool.

 

The Shark does, however, make the perfect stage relay preamp. Just leave the feedback eliminator off!

[Simon Lewis]

....a 31 band EQ is a bad tool as it rips out a whole third of an octave in one go.

 

In many GEQs it is more like an octave that's taken out. The one third octave tag refers to the spacing of the centre frequencies.

[cedd]

I have a Sabine FBX 2400 in my rack. It does get used quite often, but only in specific circumstances, namely on hanging mics and float mics. I tend to put it across the specific subgroup, though would never strap it across the entire mix. It's never in "auto" mode, I use it simply as a set of fixed frequency filters. I find it buys me an extra 3-5dB's of gain from the mics in most venues. In a theatre role, this is one of the few circumstances I find them of much use, but they're enough use to warrant me having one.

[Original Beef]

I used a Behringer one, can't remember the model but it isn't the shark it's the rackmount version. It stopped saving settings so I don't use it any more. I've also had a bad experience with old sharky. I installed one into a church and to be honest it was terrible and completely wrecked the sound so I took it out. I currently aspire to a Sabine which are generally regarded as the Rolls Royce of FB destroyers etc.

 

I'm not really sure about the FB destroyer versus graphic eq argument as they are very different tools in my opinion and both have their uses. Ideally you would have and use both depending on your situation.

[RichM]

I'd take a decent parametric (DN410) over a graphic or feedback killer any day.

[timsabre]

We've had the behringer rackmount one in our church for about 6 years and it's worked fine - we use it in fixed mode rather than auto and it does not noticeably affect the sound. As everyone else has said, it takes time to set up well, but is useful to tame the system a bit for inexperienced sound operators. In auto mode it's hopeless, just keeps grabbing frequencies then letting go of other ones.

[tolley1466]

I'd take a decent parametric (DN410) over a graphic or feedback killer any day.

 

Agreed. It's a lot easier to tune a system with a parametric than a graphic. However, for a grab eq I'd certainly have a graphic as well.