Feedback Destroyer

andyg_prs

Hi, 

This is actually for our Violin / Mandolin / Banjo / pedalsteel + guy.....with certain instruments, most often banjo, we struggle with feedback.  He's tried a basic noisegate on a Boss FX floor unit but it's not doing the job.

I was wondering about one of the feedback destroyers, I can see for example rackmounted like the Behringer FBQ1000 or the newer FBQ2496 and the standalone Behringer Shark FBQ100.......but they all refer to microphones......

So I guess the question is whether these might work for him.....I don't know if they incorporate a noisegate but I know that in rehearsal, we sometimes kill certain frequencies on the mixer....but obviously that will be quite crude and the targetting seems much better on these things....

Any experience / opinions to share?

Thanks,
Andy

PS - the bassist uses a double bass sometimes with similar issues...

Philtheguitar

Sorry - I don't know about feedback destroyers, but feedback is often alleviated by well thought out EQ cutting, and by appropriate mic placement.

Danny1969

Well they do work, basically by engaging notch filters at the offending frequency.

I used to use a Behringer one back in the day, still got it

ESBlonde

The trick with fb destroyers is to limit the number of notches to 3 otherwise you hack all the meaningful frequencies out of the sound. Secondly once each ‘auto’ seek has found a problem frequency change it to a fixed filter to stop it deepening and widening the notch. 

What people often forget is that poor frequency response can be caused by lower quality mics, pickups, transducers, monitor wedges etc. Now in some cases those irregular frequency responses are part of “the sound” I.E. the SM57 on a snare drum, but cheap pickups badly mounted on a stringed instrument might be ok in a gentle rehearsal situation, but take it to a live and lively stage could be asking for trouble.
So think about investing in those core elements first, a good mic/pickup correctly positioned and a quality modern powered wedge with a nice smooth response curve. Once you have that sorted you may find the fb destroyer is not even needed. 

Of course your own experience may be different, since the OP has a problem with multiple instruments I’m wondering if the wedge is the common problem. If there is no wedge and it’s all going through a combo then there’s your problem.
just my £0.02.

Stratavarious

All our digital desks have it as a feature. My A&H will do up to 16 notches on each instrument/channel and monitor for feedback automatically.  Noise gates too. 

So before buying more kit, check out modern wireless mixers for it as a feature maybe,

That said, I’d be looking to sort out at source… monitors, mic positions/pickups, etc.  IEMs can help eliminate a lot of stage noise monitoring feedback.

andyg_prs

Thanks all - I don't have the exact details of how the guy amplifies each instrument.....my OCD only extends to my own setup....that has now feedback issues.....  No doubt the issue is the pickups etc he is using, as he has the issue in most scenarios including rehearsal.   He's far from technical - but a superb musician.  

I think a cheap secondhand feedback destroyer is a reasonable experiment....

Danny1969

If you want to try one I can help you with that, shipping would be £12 ish to UK Mainland but I have a Behringer Feedback destroyer Pro you can have for £30 if that's something you want to try 

andyg_prs

That sounds very interesting    Do you have a link to the actual model I could take a look at please as there seem to be quite a few variants?

shufflebeat

Stratavarious said:

…I’d be looking to sort out at source… monitors, mic positions/pickups, etc.

This ^^^

The feedback destroyer is a not-very-good answer to a completely different problem. I’ve had two and don’t use either of them now. It will work a little bit but there are several issues that make it unsuitable solution. I can go into that more if you want but I think you’ll find out for yourself.

Playing amplified is not the same thing as playing acoustically and there is a potential problem for every type of instrument. Fortunately lots of people have encountered these issues before and have developed answers, unfortunately many people who discuss this don’t really check their opinions against real life stressors.

You have to start at the instrument/pickup and optimise the source, fixing it later always comes at a cost.

This doesn’t have to be an expensive project but you can spend lots of money and get little benefit.

Sporky

I always regarded feedback destroyers as a bit of an admission of failure. 

Roland

shufflebeat said:

The feedback destroyer is a not-very-good answer to a completely different problem. ...

This is my experience too. At one point we had a singer who needed to be very loud in the monitors to stay in near tune. She looked attractive, but had poor mic technique. Consequently we were always getting feed back. We had a similar problem with an acoustic guitar. We tried a feedback destroyer, but it cut wide swathes through the sound. A 32 band graphic EQ was much more effective.

ICBM

A banjo is an absolute bastard for feedback, especially if it has a piezo pickup on the head - the head resonates really easily, so the feedback loop gain is quite high. Likewise the whole body on a double bass, although not as difficult to deal with because it tends to be more limited to one or two problem frequencies, whereas the banjo head has a pretty wide frequency range.

You could try putting some foam rubber in the resonator behind the head - not tightly stuffed, but just enough to damp the head. It will ruin the acoustic tone, but it won't affect the amplified sound as much.

Sporky

I find you can solve it by putting the banjo into one of those 120-litre wheelie bins, filling said wheelie bin with expanding foam, and burying it.

shufflebeat

Consider this for banjo:

https://www.canford.co.uk/Products/92-611_SENNHEISER-e609-MICROPHONE-Dynamic-super-cardioid-guitar-cabinets-silver

This is a mic normally used for electric guitars and drums so it can deal with high SPL. Easy enough to fit in most banjos and sounds - like a banjo.

You might think it’s asking for trouble to have a mic effectively pointing at a monitor but usually the banjo is so relatively loud that the gain on the mic is pretty low so it’s less of an issue than you might think. Also, ideally the monitor is pointing at your head, which isn’t in the same place as the banjo.

As an experiment, cable-tie a Shure ‘57 or ‘58 (little bit of foam wrapping) to the inner brace and have a listen.