Feedback Eliminator?

[glenfong]

Anyone have any good experience with either of these for db?


I'm using an Underwood with Fdecks preamp/hi-pass filter and I have a Fishman Full Circle (sounds real boomy, so it's not used a lot yet). Amp is a EA iAmp800 with either (or both) EA Wizzy 10" or EA M-Line 12".

I played in a semi-large band (3 horns, electric piano, drums, vocal, upright bass) doing ballroom dance music (mostly jazz standards) in a very large and long ballroom and the dancers had trouble hearing the bass with only the 10". Added the 12" (stacked on the 10") and it helped somewhat. The wooden stage was elevated about 2 feet. I was at the edge of feeding back most of the time (except on ballads). This is the loudest I've ever played the db, plus I was standing much further away from the speakers than I normally do, it was blazing. The hi-pass filter worked to some degree. Was wondering if a feedback eliminator would help to get more volume? I could try and run a line to the p.a. next time, but there wouldn't be anyone tending the sound system.

Thanks, Glen

[Ric Vice]

Originally Posted by glenfong

Anyone have any good experience with either of these for db?


I'm using an Underwood with Fdecks preamp/hi-pass filter and I have a Fishman Full Circle (sounds real boomy, so it's not used a lot yet). Amp is a EA iAmp800 with either (or both) EA Wizzy 10" or EA M-Line 12".

I played in a semi-large band (3 horns, electric piano, drums, vocal, upright bass) doing ballroom dance music (mostly jazz standards) in a very large and long ballroom and the dancers had trouble hearing the bass with only the 10". Added the 12" (stacked on the 10") and it helped somewhat. The wooden stage was elevated about 2 feet. I was at the edge of feeding back most of the time (except on ballads). This is the loudest I've ever played the db, plus I was standing much further away from the speakers than I normally do, it was blazing. The hi-pass filter worked to some degree. Was wondering if a feedback eliminator would help to get more volume? I could try and run a line to the p.a. next time, but there wouldn't be anyone tending the sound system.

Thanks, Glen

Glen,
Well feedback is very dependant on the acoustics of the room you are playing in and the chaacteristics of you're instrument. Personally the first thing that I would do is get a "vibramute" for the after length of the strings below the tailpiece. Here is the maunfacture.

Don Payne c/o Jazzazart Productions
861-NW Avenue
Plantation, Floridia 33317

1-800-406-2320
http://www.recyclednotes.com/
email:recyclednotes@comcast.net

They cost $6.00

[jlilley]

If your amp was sitting on the wooden floor, I'd try putting it on a chair or milk crate. Decoupling it from the stage floor could make a big difference. Fdeck's filter should do more or less the same job as the feedback destroyers.
Good Luck,
John

[Mike Arnopol]

Best thing is a parametric eq. If space is limited get a one or two band pedal. If not, get a single rack space 4 or 5 band. Make sure that it's fully parametric---that it has a variable "q" which means that you can narrow it down to a notch filter. Then you can use whatever leftover bands for eq. Once you get used to using it, no other type of eq seems as good. I also use an Iamp 800 but still need an outboard eq to tame the upright. Not just feedback---you can tame some of the nasty resonances too.

[Andrew McGregor]

A feedback destroyer is basically an automatic notch EQ. I agree you need the parametric AS WELL, to get the resonances toned down, but the feedback destroyer ought to work on top of that to catch anything you miss. They work fantastically for vocals, but I have no experience on bass myself.

[glenfong]

Good suggestions, gives me more things to ponder. Most appreciated!

I will try the 12" elevated by itself this week. It was sitting on top of the 10" last week, so the 10" was coupling with the stage floor. The amplifier is sitting on a small folding keyboard stand behind the speakers instead of directly on top of the speaker btw.

A parametric would cut a bigger piece of bandwidth than the notch cuts of the feedback eliminator. I'm thinking it would also cut down the frequency bands that I'm trying to keep. Fdeck's device worked up to a point, with even more lo frequency cut though, the sound was too thin (point of diminishing returns).

Thanks for the after length tip Ric, I will check it out. Currently I have a strip of velcro wrapped around the after length

[seamonkey]

Check other brand feedback eliminators. Some let you take any number of the notch filters and use them as parametric filters. Still narrow notches are your best bet. The feedback eliminators only make the notch as deep as it needs to be.

[Andrew McGregor]

Originally Posted by glenfong

A parametric would cut a bigger piece of bandwidth than the notch cuts of the feedback eliminator. I'm thinking it would also cut down the frequency bands that I'm trying to keep.

It won't take away your tone. IF (and only if) you use it correctly, it will greatly enhance it. That's a bit of an art, so it will take some practice to get it right. Basically, the acoustics of the speaker/stage/venue combination will enhance some bands, possibly by a lot, and cut others. What you do with the EQ is try to flatten out those peaks and troughs; that's why it's called an equaliser. EQ is an essential step in getting an amplification system producing natural-sounding results.

Feedback results from a harmonic of your sound hitting one of the peaks in the room response, and the massively amplified version coming back in through your mic or pickup… and getting amplified again… and you get the howl. Now, if that doesn't quite feedback, it still sounds awful because of the huge spike, which is why you absolutely want to EQ it out anyway. Sound done without correct EQ is very tiring to listen to, and can also be damaging to the hearing at surprisingly low volume.

You can't do this without a parametric EQ, because ordinary tone controls can't be specific enough.

I haven't amplified my double bass, so I can't be more specific than that, but I do have a parametric in my bass guitar setup for the tone benefit, even though that instrument essentially never feeds back.

[Bruce Lindfield]

Originally Posted by Andrew McGregor

A feedback destroyer is basically an automatic notch EQ.

They work fantastically for vocals, but I have no experience on bass myself.

I'm no expert in this area - but aren't we talking about two completely different things here..?

So - vocalists with mics and Double Bass players with large hollow things that tend to resonate when amplified...?

[Andrew McGregor]

Originally Posted by Bruce Lindfield

I'm no expert in this area - but aren't we talking about two completely different things here..?

So - vocalists with mics and Double Bass players with large hollow things that tend to resonate when amplified...?

Vocalists get feedback because something in the room or PA or the vocalist's body or somewhere is resonating. So do bass players. The electronics can't tell the difference.

[Bruce Lindfield]

Well - there is a particular kind of Double Bass feedback, which is very common - a low rumbling sound that builds...?

I've heard this a lot with newbie DB players - a sort of "woofing" sound which to me is completely different to the kind of feedback you get from mics and in completely different scenarios..?

So we have talked about this before on here with the experienced "regulars" of TB and they have said it is an inevitable consequence of such a large hollow body - so it never happens with slab or bass guitar.

I played bass guitar for many decades and feedback was never an issue - but then getting into Jazz and going along to workshops and summer schools with lots of newbie DB players and it is a huge issue.

So - exact same circumstances/venue with BG - no feedback problem - turn up the volume on DB and "WOOF"!!

[Andrew McGregor]

Oh, yes, that is resonant feedback, just at a much lower frequency than you get from a mic in free air. There's no reason in principle a feedback eliminator couldn't stop that, but I don't know if it works in practice because I've never tried. It is possible that the frequency is below the working band of an eliminator designed for vocals.

In any case, it's not hard to do the test; show up in a shop with a bass with pickup fitted, find the patch cables to feed it into a feedback eliminator, plug into any bass amp lying around, and see what happens.

I have a strong suspicion that this does in fact work, because I used to do a big amplified outdoor concert with the orchestra every year. We used to get that same growling feedback from the bass section, using mics. One year that just stopped, and in fact all the feedback stopped, and I noticed (because I took an interest in the gear) that the sound engineer had showed up with a rack full of feedback eliminators that year.

[steve_n_his_urb]

Hi,
I tried a behringer DSP Shark - i think it is very similar in design to the Sabine units in your post. I found it not really suitable in 'automatic, real time' mode for DB. Literally each sustained note you hit takes up a new 'notch channel' - you see an extra red light light up, and then the next time you hit that note, there is nothing there - it is filtered out. There is a mode where the device generates clicks and anayses what comes back, then presets the notches. That might work if you have the luxury of time during a sound check after the sound system is set up.

i read an online article by someone from Shure or AKG about feedback elimination (try google). They suggested that you only need a gentle notch of 3dB or so, not the sledgehammer 16dB or more these devices switch in. Also, the importance of phase was stressed in the article - which could be a 180deg phase switch, or simply taking a few steps to a new spot on the stage and moving away from where the troublesome frequency is beating.

I am currently playing about with a Behringer PEQ 2200, it has high and low pass filters and 5 parametrics. I currently use the HP and only one channel, set around 160-170hz as a 'resonance' filter, about 5dB of cut and less than half an octave wide. The PEQ is big and clunky, mains powered and the controls actually 'click' into each position (not continuous sweep), also i had to remove the rack wings and tack on some home-made covers so it could travel nicely with my gear. But with patience, it is a nice way to find what works for me.

I am experiencing very few problems playing in fairly quiet ensembles - with a 10mm omni electret as my pickup.

Steve

[Andrew McGregor]

So, that seems to indicate that unless the device can be set for less cut, or to reset itself after a short period of time, it's not going to work well in automatic mode. Interesting.

[seamonkey]

I don't know about the Shark, but another one has a way to lock the settings after it "learns", or after you manually set it. With a "Panic" button for those special times. Letting it run in automatic mode is usually only good for voice only. The manual describes this.

Also, it only notches as deep as it needs to. Not just automatically to as deep as it can. That article might be first generation.

[glenfong]

Steve, thanks for the tip on the 'Shark'. I read someplace else that it would cut too much out, kind of like killing a fly with a cannon. The FBX solo has decent specs, 1/10 octave width and resolution of 1/50 octave plus the filters can be locked to any number after the feedback points are identified and squelched. I probably don't need all of the 8 available filters.

My Eb would start to howl (there's the Woof!) if held any longer than an eighth note and the amp's on board eq is wide enough that it cuts too much tone. I dug out an old MXR graphic eq that I'll try on this week's gig. It just may work if a -3 dB cut at that frequency is all that it needs.

Researched some of the pro parametric eq's and they can run into the $1k range and more! Trying to keep the cost reasonable too.

My buddy Will recommended a direct out to the p.a. too (the horns and singer are mic'd) I'll check if the keyboards are running to the p.a. as well. He said it's a loosing battle trying to fill that room with my stage sound only since I'm using the acoustic instrument and fighting the feedback issue.

I've installed the larger Sabine in some of the Municpal and Superior courtrooms (I take care of the sound systems for the courts in this county) and they do work fine for voice/speech (wish I had a spare to experiment with on the bass). I'm not expecting any miracles, but I have a bunch more ideas to try, thanks for the your thoughts, guys!

[bolo]

Originally Posted by Ric Vice

Personally the first thing that I would do is get a "vibramute" for the after length of the strings below the tailpiece.

Originally Posted by glenfong

Thanks for the after length tip Ric, I will check it out. Currently I have a strip of velcro wrapped around the after length

I think your velcro is equivalent to the Vibramute, functionally.

Raising the cab off the floor sounds like a real good suggestion to me, esp. if the wooden stage is hollow or semi-hollow underneath.

[ZachDad]

I'm not sure if anyone has mentioned this one yet...When I get in loudest situations the first thing I try (after the handy afterlength dampening) is to roll up a piece of black foam (sonex or the like) and sqeeze it between the tailpiece and the body of the bass. Being black it won't show much and really seems to slow the FB down.

[TVD]

I love my feedback destroyer! I don't know about the Sabine ones you posted pics of. I bought a much, much cheaper Behringer Feedback Destroyer Pro 1124P. I picked it up cheap used. I wasn't having problems with feedback in low to moderate volume situations, but in loud volume situations, I was having quite a bit of trouble with feedback, and I was taking away the fun of playing upright in those situations, so I tried a feedback destroyer as a hopefully cheap fix, and for me, it's worked wonders.
Now, it's not easy to get it set up. The one I have is a parametric EQ. I tried to set it up myself the first time, and I then had a gig that's not real loud, but I've always had trouble with feedback on that gig anyhow. I didn't have any feedback during that first trial run, but it also sounded just terrible. Just sucked all the sound out. I hated it.
I then took it over to the guys house who gave me lessons. We screwed around with that thing for a few hours, but it paid off. We ended up setting it up string by string, and were finally, and I do mean finally, able to play loud in his house with no feedback, and with a tone I was happy with.
A few days after that I had a loud gig, in a place I had played once before and had big trouble with feedback. I set up before the show, and when I hit a note it sounded loud, fat, and zero feedback. I was like woah, is this real? But it was, I had zero trouble with feedback that night. The drummer noticed it right away. He said, man, that thing sounds great and no feedback at all. There was another bass player in the crowd that night too, and he commented on how good the upright was sounding out front. The singer didn't notice anything at all. Go figure huh?
The next time I played the gig where I had the first trail run with the feedback destroyer, where no feedback but the tone was terrible, the guitar player noticed. He came to me on break and said the upright is sounding really good today, and not squealing at all.
I thought I would have to change the settings for different rooms and stuff, but I haven't. It's been just plug in and go since we got it set up right, and I haven't had one feedback problem since, and I've been happy with the tone. It's def given me considerably more headroom. It's just so nice to not have to watch where I stand and all that kind of stuff I was trying to do when fighting the feedback monster on a gig, which was frustrating.
The Behringer feedback destroyer actually is a user friendly unit, but only if you know what you're doing on it. It takes a lot of tweaking to get it set, but once set...Well, I swear by mine now, but I can see why people might say it's "junk" or whatever, cuz when not set up right, it's bad news and will kill the tone.

[srxplayer]

The Sabine products are excellent and probably the best feedback suppressor products on the market. I have experience with them and own a couple of the 2400's.

They are designed to be used in FOH and Monitor channels of a PA system. We use them in a sub group/mix for vocals. They work well for that. I don't know how well they will work for an instrument because they may very well notch out frequencies that destroy your tone. I'm not so sure that it would be the best answer for your problem.

I wouldn't recommend the Behringer. Not because it doesn't work but because the 12 filters notch out too much of a frequency. I own a couple of these units so I learned their limitations from experience. They tend to be confused by guitar leads and distortion patches. They work ok for contrling feed back at speaking engagements though, so they do work.