# Feedback Problems



## Guest (May 10, 2006)

*A quick hello*

Greetings fellow AV enthusiasts.
I stumbled upon the site when researching Parametric EQ for my new church PA. :blink: 

I have a background in live PA from my undergrad med student days in London at both Kings College Hospital where I ran the tech support for the student union and Imperial where I assisted in the radio station doing more menial tasks. :snoring: 

My ongoing involvement with sound technology continues with a new involvement with church PA which I've had a hand in for about 18 years, and boy have there been some changes in that time! :dizzy: 

Now enjoying a little home theatre and looking forward to gleaning some pearls from you all.

Drop me a line if you've got any nuggets of information about feedback elimination or dealing with very bright rooms.


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## Phil M (Apr 19, 2006)

*Re: A quick hello*

Welcome to a fellow Brit.
I normally find adding a dimmer switch helps with a bright room! Just kidding.
Normally soft furnishings help as the first step, followed by acoustic treatment. There are a number of posts on the internet on DIY approaches, sorry I don't have any of these saved - hopefully someone will jump in.


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## Sonnie (Apr 11, 2006)

*Re: A quick hello*

Hey Dyer and welcome to the Shack!

The BFD will definitely handle your feedback problems... that is of course what it was originally designed for and it does it automatically.

I'm with Phil on the bright room... turn the lights down... or wait til the batteries run down. :R :sarcastic:

We have a problem in our fellowship hall with really bad echo since we remodeled it. We took the lowered ceilings out and dressed up the original cathedral ceiling. Plus we took the carpet up and installed ceramic tile. All walls are sheetrock. If you only have about 10 folks in there you can't even talk and understand each other. We are in the process of getting some heavy drapes to go over the side windows and plan on building some frames of insulation and covering them with the GOM material. We'll place them all around the room.

You might post a question about this in the Custom Installation forum and see if you can get some more input.


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## Danny (May 3, 2006)

*Re: A quick hello*

Welcome to the shack Dyer. I have been involved with professional sound systems for some time now so if you have any questions about them give me a yell. In terms of EQ I like using the Sabine gear the best - www.sabine.com look at the GraphiQ2. In terms of reducing the echo heavy padding would be the best unless you want to move everything outdoors  

Regards 

D.


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## Guest (May 11, 2006)

*Re: A quick hello*

Wow, all this in 7 hours...

I've used the SABINE FBX SOLO's previously and have a pair in the system at the moment,taking the whole mix. I know they are supposed to only filter one channel but I borrowed some to use as a proof of concept - Vicar is suitably impressed.

We've just had an acoustic engineer in to do a frequency response plot and come up with some suggestions but it's likely to come down to acoustic battening along at least one wall. The Vicar isn't exactly won over with that idea yet...

Feedback/EQ wise I'm looking at Behringer as a more cost effective solution than either Sabine or Shure. That's certainly true here in the UK where the DEQ 2496 is available for 215GBP and the Sabine is about double!

The DEQ 2496 seems to do all that we might need it to do and more but with only 10 filters/channel I'm wondering if the BFD 2496FBQ is a better solution with 20/channel. I've got a Behringer 1/3rd octave EQ ready to complement the BFD at need.

Anyone here have any direct experience/comments to share on the equipment proposed?

TIA.


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## Wayne A. Pflughaupt (Apr 13, 2006)

> The DEQ 2496 seems to do all that we might need it to do and more but with only 10 filters/channel I'm wondering if the BFD 2496FBQ is a better solution with 20/channel.


If it’s just for feedback, you really shouldn’t have 10 feedback points, much less 20. If so, something is fundamentally wrong with the way your system is set up.

Anyway you cut it though, a parametric EQ set with extremely narrow filters (1/10-octave or less) is your best bet for dealing with feedback.

It needs to be asked, what’s the source of the feedback?. For instance, if it’s just a lavier mic, then you don’t want to EQ the whole system, just the channel that mic’s on.

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

> Plus we took the carpet up and installed ceramic tile.


Gee Sonnie, where were you when they needed you?  I doubt some curtains and a few treatment panels will make a difference as long as the floor is tile. And I imagine that cathedral ceiling is hard wood, right? Only a little better than tile, acoustically-speaking.

Regards,
Wayne


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## Sonnie (Apr 11, 2006)

I warned them of what was going to happen, but the ladies would not listen. They had to have tile. "It's easier to clean up after all these kids eating in here." "It will be so much prettier." My response... how is it easier to have to sweep and mop a tile floor than to simply vaccum carpet and we are a congregation.... who are we trying to impress?

The ceiling is actually sheetrocked now. When I say "some frames of insulation" (or acoustical panels)... I'm talking major 4' X 8' sections all around the room. However, I'm not sure that will ever even get done... and you are probably right... I don't know that even that is going to do much good with the size of the room we have and with that much tile.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hee hee – well, at least you tried! I wonder what the ladies have to say about it now! You should hold regular services in there once and a while so they can suffer along with the rest of you! :rofl:


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## Sonnie (Apr 11, 2006)

True story... us men have a little group that meet weekly and there's about 8-10 of us usually. We met in there one day... sat down at a long table and we literally could not understand each other unless we were sitting next the person talking. It was horrendous so we move to the sanctuary. They then realized we should have controlled the interior decisions instead of giving in to the ladies. lol Go figure!


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## Guest (May 14, 2006)

At church this morning I deployed my new Behringer 1/3rd octave EQ. Lots of pretty lights to dazzle the curate but starting to make some progress with the overall response of the hall.

Before the service started, our vicar said that the main church sounds a little like an empty swimming pool and several of the older members of the congregation are reporting real difficulty with muddy sounds. It's wonderful for instrumentals but absolutely awful for vocal clarity.

We are now looking seriously at acoustic tile, banners, drapes, anything to soak up some of the reflected sounds.

I'll let you know how it turns out and maybe put up a minisite with the pics.


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## Danny (May 3, 2006)

You may be able to fiddle with the EQ to get a better sound but from what you've told us about the room your working with It does sound to me like it will come down to some heavy padding.


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## Fincave (Apr 20, 2006)

You may want to have a look at http://www.ecophon.co.uk/default____5334.aspx They are a company that make acoustic panels for various solutions, hospitals, schools, offices etc. If you get in touch with them they may be able to advise you as to what you will need. Their website is fairly informative as well. Hope this helps


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## boyce (May 9, 2006)

Correct me if I am wrong, We just finished add acoustic panel in a multi-function hall, and I want to share with your guy is, you can easy to control the feedback by feedback killer or Digital Multi-Mode Equalizer (inter-M MEQ 2000) which we used in there, and it work out great, but we still have (big) problem for the echo, reverb etc, those never ever can be control, expect install acoustic panel. Beside before panel installation, the acoustic eng is hired (my arm & my leg) to design what type panel to be installed.

for sure next time, I will do the acoustic test before design/install PA system, .


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## Danny (May 3, 2006)

Generally Feedback can be controlled by a feedback exterminator , however you can also get the shower/field problem. Okay so if you had a PA system in your shower (or other small room) and you had a feedback problem if you added a feedback exterminator you may only be able to get 2-3 Db gain. If though you had a PA system in a wide open field you would have to really crank the system before feedback started, if you then added a feedback exterminator you would be able to get 10Db or more extra gain out of it because of the large amount of space between feedback points. In the shower situation you would have a lot of feedback points concentrated together but in the field they would be widely spaced.

D.


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