Feedback Management

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Feedback Management

Post by twotoedsloth »

Hello,

Many thanks for taking the time to read this and hopefully offer some advice.

I am looking for a feedback suppression device, for a small hall, seats about 500. The speakers attached will be Meyer Sound Ultra X40s.

I was thinking of two boxes, the dbx AFS2, or the dbx Venu 360. Is the Venu worth the extra $500 USD?

Please let me know what you think,

Peter
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Re: Feedback Management

Post by AlecSp »

Save your money and learn how to optimise your system (mic choice, mic usage, positioning, appropriate levels, EQ, acoustic treatment)

No feedback suppressor is a magic bullet, as so many have discovered over the years.

In the end, the factors I mentioned will have far more impact than any processor driven dumb. Though you'll never be able to beat simple physics.

And I'd hope that, with that level of FOH speakers and venue, you'd have the budget, people and kit to deal with engineering appropriately.
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Re: Feedback Management

Post by resistorman »

^^
second this.
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Re: Feedback Management

Post by Wonks »

If this is for music, rather than theatre, then you are very unlikely to get feedback from the FOH speakers unless people are using mics in front of the speakers.

99.9% of feedback is from monitors.

Keep the stage instrument levels under control then the monitors don’t need to be as loud and you can seriously reduce the risk of feedback.

In-ear monitoring reduces the risk to almost nothing.

Inexperienced stage acts are going to be the main problem.

If you are using stage monitors, then 31-band graphics on each one notching out the most prone to feedback frequencies will help, but if the mics change each time, then the problem frequencies are likely to change with them. So it’s sorting things out at the soundcheck and learning to tell what frequencies are feeding back so you can adjust the graphics accordingly.

But far better to have everything set up so there’s no likelihood of feedback to start with.
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Re: Feedback Management

Post by Mike Stranks »

Yup!

Feedback suppresion devices IME are never that useful. As others have said, far better to spend time looking at configurations, levels and channel and various 'group' EQs - especially FoH.

Might be a good idea to find an experienced live-sound buddy to sit-in on some gigs and help sort out actual/potential feedback issues.

(I was at a large funeral on Monday. Sophisticated digital sound system. Pulpit and lectern mics on the verge of ringing the whole time. I yearned to nip back and tell and show the operator how to apply some judicious lo-mid cut to ameliorate or eliminate the problem. Obviously I didn't! :) )
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Re: Feedback Management

Post by Luke W »

Agree with all that's been said so far. There have been more than a few times that I've solved these sorts of problems simply by pointing an amp in a slightly different direction, moving a monitor to the side (or, heaven forbid, just turning something down a bit!) and so on.

Mike Stranks wrote: Thu Jul 07, 2022 8:25 am (I was at a large funeral on Monday. Sophisticated digital sound system. Pulpit and lectern mics on the verge of ringing the whole time. I yearned to nip back and tell and show the operator how to apply some judicious lo-mid cut to ameliorate or eliminate the problem. Obviously I didn't! :) )

There's definitely a time and a place isn't there... :)
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Re: Feedback Management

Post by MOF »

(I was at a large funeral on Monday. Sophisticated digital sound system. Pulpit and lectern mics on the verge of ringing the whole time. I yearned to nip back and tell and show the operator how to apply some judicious lo-mid cut to ameliorate or eliminate the problem. Obviously I didn't! :) )

A related topic, sadly last year two relatives died months apart and their funerals were streamed on the internet, one audio channel was from the lectern microphone, the other was from the on-board camera microphone at the back of the room. The latter overwhelmed the former and made it, at times, impossible to hear what was being said.
I was able to record just the lectern microphone and send it to family members, they appreciated being able to hear the service clearly.
I had to repeat the process for the second funeral because nothing was done to route the lectern microphone to both channels, despite my comments being forwarded to the company providing the system.
Also I agree with the replies, best to use the laws of physics to your advantage than a feedback eliminator, once it can’t cope there will be horrendous feedback.
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Re: Feedback Management

Post by MarkOne »

Mike Stranks wrote: Thu Jul 07, 2022 8:25 am Pulpit and lectern mics on the verge of ringing the whole time. I yearned to nip back and tell and show the operator how to apply some judicious lo-mid cut to ameliorate or eliminate the problem. Obviously I didn't! :) )

Probably the operator wouldn’t have known what EQ was anyway. Midweek funerals are always most likely not to get the experienced PA operator. (Or even a regular production team member at all)
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Re: Feedback Management

Post by twotoedsloth »

Hello,

Thanks for your kind responses. I was hoping that the feedback suppressor would make life easier, and potentially save time.

I work at a university, and I was hoping to not work for every concert, masterclass, lecturer or lecture/recital. I would like to pass this off to some enthusiastic students. The lecture recitals are the most difficult to accommodate.

Does anyone know if the feedback suppression in the Venu360 is the same as the AFS2? It might be handy to have the RTA functionality at some point in the future, or is this a red herring? If I do go with the Venu360 what mic should I be purchasing for the RTA?

Sorry if you feel I am not observing your advice. I do understand that it might not do all I am hoping for, but I have found it is relatively easy to find funds for equipment, but next to impossible to find money for an assistant.

Again, sincere regrets and thanks for your advice.

Peter
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Re: Feedback Management

Post by Wonks »

It might help if you could describe the setup, where the speakers are in relation to the microphone(s) etc and if there's any monitoring, and what sort of performances you expect to host? Is there a proper stage?
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Re: Feedback Management

Post by Wonks »

The problem with automatic feedback destroyers is that unless you set them so that each available notch filter works only once and doesn't keep reacting after that, then you end up with the width of each notch getting wider (and if allowed to, deeper).

It's very easy to end up with a terrible sounding and much quieter system.

And the once only mode is pretty much like ringing out and using a 31-band graphic EQ, but at least you've got control of that.

You'd probably need a combination of a 31-band graphic for basic system set-up and anti-feedback duties, and an auto feedback suppression unit, set for single use operation, which will need to be reset each time the system is used (if the kit isn't powered off between uses and doesn't auto reset).
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Re: Feedback Management

Post by twotoedsloth »

Hello,

Thanks for your patience, I had to figure out how to post an image here again.

http://walterhallrecordings.music.utoro ... forSOS.jpg

I'm sorry for appearing to be recalcitrant.

This is the hall I will be installing the feedback eliminator in. A big part of why we have feedback issues is because the speakers are hanging on the walls behind the performers. I can usually manage by manually adjusting the EQ to remove the offending frequencies, but as I said, it would be a tall ask to put that on a student with little to no experience.

Please accept my sincere apologies for appearing to spurn your advice.

Thanks,

Peter
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