So, I tried a feedback eliminator last night...

[wesg]

I've been curious about introducing one of these into my setup for sometime, but have not been able to decide whether there would be any real upside -- particularly given the prices on things like the Driverack and Sabine units. So, when an old Behringer unit (DSP1100P?) showed up in the local want ads for 40 bucks....I figured I had nothing to loose but $40 and gas money.

 

I ran it in series with my 31-band GEQ, out from the board and into two monitor mixes (three NX55Ps altogether) in my basement for rehearsal. My basement has hard walls, laminate and tile flooring, low ceilings, glass doors, big windows... it's the kind of room where getting decent GBF can be difficult.

 

I kept the GEQ in "bypass" all night, and set up the Behringer by picking factory program 3, which is a mix of single-shot and automatic (hunting) filters (it has 12 filters per channel, two channels). Then I turned the gain on one monitor mix down, and turned the gain progressively higher and let it pick off frequencies until most of the "doing something" lights were lit. Then I did the same with the other monitor mix. Then we rehearsed for three hours.

 

Result: I had a LOT more usable GBF, and found it much easier to just let the Behringer do its thing than to go "check check check" a billion times hunting for the right slider on the 31-ch GEQ. I did not lock any of the filters, and I noticed at one point that it dropped an important frequency mid-song and we got about 500ms of minor howl before it clamped back down on it. We also got a much better-sounding vocal than I was able to achieve in the same space with the GEQ, as I had to carve out a lot of stuff around 2K. The narrower Q of the parametric EQ really helps here.

 

The room also has some modes around 100-160Hz -- several distinct ones, listening to the Behringer learn -- and I had been carving those out with the GEQ, but not as well as the PEQ allows. The result was that with the GEQ reverb always sounded boomy (singer really wants reverb in monitors), whereas last night it was pleasant and did not run away even when the place was drenched. An unintended side-effect of this was that all of a sudden the kick was LOUD. I had to turn it down. I must have been chewing a lot of the kick signal out with the GEQ too.

 

My piano sounded funny to me a few times last night, but not in any way I could put my finger on.

 

Conclusion: I think I'm going to keep an eye out for a unit I can count on -- Peavey Feedback Ferret, Driverack PX, Sabine Feedback Exterminator -- and use it in my monitor rig. I also need to get the programming better, so that I lock in key frequencies at the start of a night. I don't think I want to run my FOH through a unit like this.

 

What do you guys think? Any other products I should be watching for?

 

Wes

[nchangin]

Is the piano using a direct in I take it? Assuming the eliminator chopped some frequencies your used to hearing, that's a bummer. Glad it worked for you, interesting to hear your experience using this, thank you for sharing

[dboomer]

Congrats ... You had good luck with one of the poorer performers. Imagine if you had tried a good one

[dbMontana]

Congrats ... You had good luck with one of the poorer performers. Imagine if you had tried a good one

 

So Don, I'm guessing I could research this myself but you'd know right off: Ideally shouldn't each AUX-send/monitor-mix have it's own "feedback eliminator" channel as opposed to chopping frequencies out of all monitors when only one on them is actually feeding back?

[dboomer]

That might be the best way if you know that only a single monitor is the problem. But generally the best way would be to use FBS on each input that might be problematic

[wesg]

Don Boomer - That was pretty much what I was thinking! After hearing so much negativity about FBX-type devices, I was not ready to spend any real money, but when this one showed up for cheap, I figured, "why not?" ... now I will be watching for a better device at the right price. I'm willing to pay much more now that I've had the chance to try this 10-year-old Behringer unit. One thing with the Behringer, WOW, you do not want to accidentally turn the unit on and off with your speakers on. Holy Mother of God, it gives 2 or 3 REALLY loud pops that must be full DC rail swings during power down.

 

nchangin - Yes, the piano is direct-in to the board, and that's probably what's going on. I have my own monitor mix. On the plus side, my "bright piano" patch sounded better than usual. I can totally live with this; I'm probably the only one noticing and it doesn't go that way to FOH anyhow.

 

dbMontana - I have seen a few ways of hooking these up; one per monitor mix is what I tried. I did not link the two channels on the Behringer unit, even though that is an option. I have also seen devices intended to go in between a single microphone and the mixing board. I would be more reticent to use one of those, since it will affect FOH sound...but if it works fast and with a very narrow Q, I think it would have the potential to work very well and sound very good...especially in a situation where your guitars and synths are accidentally tripping filters.

[Vito Corleone]

I've got a Driverack PX sitting around without much wear-and-tear on it that hasn't been part of my system for a few years now. PM me if you're interested in it.

[RoadRanger]

That might be the best way if you know that only a single monitor is the problem. But generally the best way would be to use FBS on each input that might be problematic

Yah, I had gathered up six channels of Sabine 2020's just before I switched to a mixer with no channel inserts .

 

[dboomer]

That's not my fault

[monthlymixcd]

I'm currently down to using just one dbx AFS224 in our band's rig... usually (but not always) applied to the aux sends for the horns and/or drums monitor(s). We are a 12-piece and sometimes it's a tight stage with very few good spots for their monitors. Awkward placements = potential for feedback and the AFS224 (always run dual mono) knocks it out quickly. You got lucky with that Behringer unit... I tried two different offerings from them in this category and one was a feedback generator only and the other was DOA out of the box.

[WRGKMC]

I have a pair of Sabine's in my studio. I'm kind of on the fence about how well they work. My studio is sound proofed and a very dead room to begin with. I use them to reduce feendack when I record but the signal I record is from the mic itself so it doesn't affect the recorded sound.

 

My thing is, yes you can get the sound a bit louder, but it comes at a cost. When you start scooping narrow frequencies the mic produces you wind up with gaps in its response that affect the sounds Presence/Character/Air etc. If you leave them in auto mode they will continue to make reductions and the sound quality can get quite small and lifeless. You can check this buy pumping a CD player through the PA then bypassing them on an off.

 

So far I haven't removed them from my rack but after the last session, I'd thinking about taking a number of items out of the rack and simplifying the chain. I have other things in there like comps, gates, EQ's I really don't need and If I go back to a simpler setup with just a Mixer, and Power amps and maybe one effects unit I'm sure I can get better live tones and more up front vocals. I loaded the rack up with stuff just because I had it, not necessarily because it was the best thing for the sound. What convinced me was I took 2 of my cabs, one power head, and an old Tapco mixer and threw them into a small rack for a small party gig. Oh and I might have had an Alesis Midiverb for some mild echo. That rig kicked butt and sounded wonderful. Makes me wonder why I'm wasting my time making the rig so complex. The more knobs you have the more you have to tweak to get the best results. Maybe I'm just getting to the age where all that is just more of a headache. So long as the vocals sound goos, the rest is mostly up to how well the band is actually playing and the less distractions the better.

[agedhorse]

Since I haven't experienced feedback on monitors in probably 5 years and no act complains, and the wedges sound really good (biamped SRX-712's), to me it's a solution looking for a problem.

[dbMontana]

Since I haven't experienced feedback on monitors in probably 5 years and no act complains' date=' and the wedges sound really good (biamped SRX-712's), to me it's a solution looking for a problem.[/quote']

Andy I have no doubt you could make things work and sound good in any setting where others (certainly myself included) could not but, let's face it, your normal venue is far more acoustically friendly than most. I rarely have issues at my normal venue either except occasionally a bit of mild ringing when I push the volume on the mics between songs so that the performers talking to the audience remains intelligible over the chatter -- we're not a concert hall filled with rapt listeners but rather a brew pub of conversant imbibers. I'm not trying to champion the use of automagic suppressors either but I am intrigued by the concept -- at least in theory anyway.

[Craig Vecchione]

In my opinion feedback killers have their place; in situations such as mixing from stage by the band.

 

[nousername]

I'd like to get a couple these for work. We have a similar setup with low, hard ceilings, plus "demanding" musicians who simply won't play quieter, thus requiring more from the wedges.

 

For my band, we're close to switching to wired IEM using our Jamhub device and FMM XLR splitters to get the vocal signal to it and the mixer. For now we'll have to rely on loose fitting earbuds to allow sound from instruments not plugged in to be heard. It should be fine.

[dboomer]

I have a pair of Sabine's in my studio. I'm kind of on the fence about how well they work. My studio is sound proofed and a very dead room to begin with. I use them to reduce feendack when I record but the signal I record is from the mic itself so it doesn't affect the recorded sound. My thing is' date=' yes you can get the sound a bit louder, but it comes at a cost. When you start scooping narrow frequencies the mic produces you wind up with gaps in its response that affect the sounds Presence/Character/Air etc. If you leave them in auto mode they will continue to make reductions . [/quote'] So do you have these patched into individual channels or on the overall mix? They'll work much better on single channels. By auto mode do you means with the filters set to dynamic? Or do you mean setup mode? Setup mode must be done in complete silence. If you make any sound the unit will identify that as feedback and set a filter (which you do not need). How many filters do you have set as static and how many are dynamic?

[dboomer]

Since I haven't experienced feedback on monitors in probably 5 years and no act complains' date=' and the wedges sound really good (biamped SRX-712's), to me it's a solution looking for a problem.[/quote'] If you have 30' ceilings and a theater stage I hope feedback isn't a problem for you. OTOH for bands playing in clubs they face much different challenges.

[dboomer]

I'm not trying to champion the use of automagic suppressors either but I am intrigued by the concept -- at least in theory anyway.

So not to pick on you Dave, but just as an introduction ... So first, if there is NO feedback, then there is no action. So if you ever have feedback you have a few choices ... Live with it ( not much of an option since everyone will be heading for the doors), turn down ( ok, turn down and shut up) or fix it so that you can get the level you desire. There's nothing magic about them if you understand how feedback is created. They just measure and set very accurate, minimally invasive filters ... But only when feedback has occurred. Tools are only as good as the way you use them. Obviously some systems work better than others and there's only so much you can do with EQs because you are indiscriminately attenuating everything at that frequency. That's why they work best in single channels. Imagine if you wanted to,add bass to your lead vocal but you did it with the graphic EQ on your mains. Same thing here. I'm working on a new method for feedback elimination that does not use negative EQ but instead actually removes the feedback component from the original signal. Amazing what you can do with DSP . It will be a while til it becomes a product however.

[dbMontana]

No offense taken Don and I'm certainly not trying to argue but in the interest of learning something here: Why put the unit on a single channel and cut the feedback frequency out of FOH as well when it's most likely that channel's interaction with the AUX/monitor send that's causing the problem? Of course that's an assumption on my part to begin with. Admittedly if the unit can surgically notch out just that narrow frequency (hmmm, so how narrow is a feedback spectrum typically?) it likely wouldn't be noticed but... I can probably look a lot of this up but it's more fun asking an expert.

 

BTW, on the more general topic of automation, I'm typing this on my one-day old MacBook Pro -- the first Mac I've ever owned. Pretty amazing technology -- of course it better be for the price! I've owned PCs for the past 29 years and this is a step into a brave new world. Gonna take a bit to get used for sure. So where did Presonus Capture install to anyway...?

[dboomer]

Feedback essentially starts as a single frequency sine wave. So most times a human ear cannot even recognize it until it grows more and begins to get out of control I suppose you could just apply it to a specific monitor but I can't think of many (if any) mixers would allow to to patch it that way.

[WynnD]

In my opinion feedback killers have their place; in situations such as mixing from stage by the band.

 

Don't know if that's the only place, but it's a very good place to use them. They can kill feedback quicker than I can get to the board. Lower volume makes them unnecessary.

[wesg]

I forgot to mention one thing in my mini-review - this Behringer unit hisses pretty loudly. My gain staging is good. Maybe not perfect, but definitely good.

 

I think the unit they copied was the Sabine FBX-2020. If you're looking to buy a quieter version of what I reviewed, I would start there. The Sabine units are also, I believe, Made In the USA.

 

Wes

[dbMontana]

So sure enough, open I open my mouth a few posts back about how I hardly ever have feedback problems and then last night -- another story. I had a local three piece blues band -- drums, bass, acoustic guitar through DI and one vocal -- five channels in all. Easy schmeasy. A last minute sound check and the acoustic guitar had a weak signal and needed the gain on the mixer way up but no problem -- we made it work and did the first set ok. At break I asked if he could turn the guitar up a bit so I could back down the gain on the mixer -- not sure why, it just felt the better thing to do -- which he did and I reset the gain in the mixer during the first song. Ended up with the same input level displayed on the metered bridge of the channel as before so I thought all is well. Then along came the first break between songs and as soon as he took his hands off the strings the thing just took off in the low mids somewhere. I had my iPad with AudioTools wired to the solo bus so the Spectra display made it pretty easy to identify the 215 Hz runaway which I GEQ'd out of his monitor. Standard stuff fixed pretty quickly but it's still not obvious to me why with the same overall input level at the mixer the guitar would take off so badly unless, maybe, I suppose, the pickup was a soundboard piezo and turning it up just made that surface hotter than during the first set. Dunno. Either way, it would have been interesting to see how quickly and narrowly a dedicate FBX might have reacted. I know that the actually EQ curve of a GEQ is not nearly as "notch like" as it appears on the controls.

 

Don when you're working on your DPS solution it would be nice if you could build it as a plugin so we could use it on any/every channel of any mixer. Yea right Dave, he does work for a company you know. And while you're at it can notched frequencies be displayed in red on an RTA for individual channels? For some reason I think I'd like to know which frequencies are being addressed. No problem right?

[wesg]

I know you don't control this, but I have feedback busters, the kind that go in guitar tone holes, can be a useful addition for situations like that. Your idea to get that feedback algorithm into digital consoles and on every channel is crazy awesome. The potential for guys like me is huge!

[dbMontana]

I know you don't control this' date=' but I have feedback busters, the kind that go in guitar tone holes, can be a useful addition for situations like that. Your idea to get that feedback algorithm into digital consoles and on every channel is crazy awesome. The potential for guys like me is huge![/quote'] Yea, I know about those sound-hole covers -- my son uses one to great effect. Maybe I should keep one around at the venue just for these instances. Agreed on the utility of a good FBX but it would be nice to know what it's doing (or has done for me after the fact)! Of course I'm going to hit the send button on this message in a few seconds here and have no idea if the normal "path" from my living room to the HC servers is available or whether the message will automagically redirect through several alternate routes/nodes. Do I care about that enough to receive a report? Not as long as it works !