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[Will Padgett]

Will,

I stopped by the church the yesterday and did some tuning on the mics using the filters on the mixer. First thing I did was to turn on the HPF which right away cut out the main feedback we were getting which was a low pitch hum. I was able to get more gain after that. As I pushed further there was feedback in the 2.5k range and I cut that down a bit.

I'll tune some more this weekend when I have a second person because I was tuning with the mics in place.

We have a DBX DriveRack PA that has "feedback eliminator" and I'm thinking that may need to be adjusted as well.

Also, I confirmed that two of the wired mics we use are AT2010s. If I had to spend money, would I be better served getting hyper cardioids or equalizers for the mics like you suggested?

Enoch

What is your mixing board?  If it's digital you've probably got what you need built in. 

[Don T. Williams]

Enoch

One of the important things about using EQ's is to use as little as possible.  For room nodes causing feedback, 2 or 3 narrow cuts will get the best results.  As you add more and more filters, you will probably start filtering out the the good audio information with very little improvement in the feedback threshold.  If you using a 1/3 octave graphic EQ, this is especially true.  Most 1/3 octave graphics have filter that are at least 1 octave wide.  They are on 1/3 octave centers, but to sound "musical" the filters need to be wider, especially in boost situations.  Full parametric filters are much better for minimizing feedback.

I once say a quote from an audio engineer "famous" for working corporate events.  When ask what his most important took was for getting good sound he stated is was a large sign he held up that said "Get closer to the mic!"

[Enoch Chang]

Will, we have an analog Allen & Heath 16 Channel MixWizard 4

Don, thanks for the feedback on EQ. We'll likely have to spend some more time tuning to strike the right balance you mentioned. I don't think we're there yet but we are seeing some improvement just by setting the HPF. Maybe I need to get a flashing sign!

[Ivan Beaver]

Enoch

One of the important things about using EQ's is to use as little as possible. 

EXACTLY!!!!!!!!!!!!!!!!!!!!!

Many people "Keep whacking away" at an eq "hoping" to get more gain.

They might get a little bit more gain, but at the expense of sonic quality, noise etc.

Once you get past a couple of "WELL PLACED" (THAT is the key) filters, it doesn't really get any better.

YES you might be able to "push the fader up more", but it isn't any louder-due to all the gain that was taken away with the "EQ wacking".

[Don T. Williams]

In my first post I was mistaken about the driver compliment of the TOA loudspeakers.  I confused it with another similar looking loudspeaker that only contained 4" "full range" loudspeakers.  The TOA is a 2-way system.  I stand by my assertion (backed by Ivan) that it isn't a line array, and it doesn't direct sound over a very broad range the way you might think by just looking at it.  Again, for some applications I think it can work well.

A typo mistake in my second post was using "took" when I was trying to type "tool".  His whole point was getting people to actually speak into the mics was critical for gain before feedback and sound quality.  We have all had people that "back off" mics when the hear themselves.  The more gain we add, the more they back away from the mic.  Frustrating!

[Will Padgett]

Enoch

The eq available on that console does not have narrow enough eq filters to make the precise cuts needed to help with feedback without, as Ivan has said, affecting the quality.
Have y'all tried different locations for the mics. Moving a few feet could make a huge difference. Also sub grouping similar mics to insert an eq won't be an option as you don't have subgroups.

[Jonathan Johnson]

EXACTLY!!!!!!!!!!!!!!!!!!!!!

Many people "Keep whacking away" at an eq "hoping" to get more gain.

They might get a little bit more gain, but at the expense of sonic quality, noise etc.

Once you get past a couple of "WELL PLACED" (THAT is the key) filters, it doesn't really get any better.

YES you might be able to "push the fader up more", but it isn't any louder-due to all the gain that was taken away with the "EQ wacking".

Many times I've seen a channel with all 3 or 4 EQ knobs turned down -- usually in an ill-fated attempt to suppress feedback. The problem with this approach is twofold: first of all, if you turn down all your EQ, you've effectively reduced the gain (and haven't gained anything). Secondly, you end up with response SPIKES between the frequency centers, which, when you turn up the channel gain to get back what you lost by turning everything down, now you've got these hot spikes where feedback occurs, and since they're between your EQ bands, there's not much you can do about them. In the end, by trying to kill feedback using all of your EQ, you've just made it worse. The end result is that the vocals or speech sound hollow and whiny, and intelligibility has gone out the window.

[Irvin Pribadi]

Many years ago I found using this to be very effective: Behringer FBQ2496
It has 2 channels EACH with 20 digital parametric filters as narrow as 1/60th octave. It can hookup to a PC for easier programming.
I basically made a vocal bus and ran it thru one channel and used the other channel for general EQ of the system.
Remember to only cut as deep as needed, typically cutting 6 to 8 dB is enough as long as it is at the precise frequency.

For me once I tuned the system to my liking and then ringed out the speakers I ended up with 5-6 very narrow cuts in my vocal bus and I also had 5 wider filters to get the right vocal tone. That left me with 9 or so filters which I then set as "AUTO" feedback eliminator.

The auto filters can be set to be sticky or temporary.
Set as sticky after each service I would check and write down the frequencies it found to be causing feedback and after a few services I can see certain frequencies which were consistent and made those permanently cut.
I still left like 6 filters as auto with the temporary setting to release within 1 minute.

Overall it was very useful, no perceived impact to vocal qualities and IMO is leaps and bounds better than standard analog 31-band EQ.

[Don T. Williams]

+1 to Irvin.  I have also had good results using the FBQ 1000's and 2496's.  These units offer two channels with either 10 or 20 tri-mode digital parametric filters.   I find 4 to 6 fixed filters in the "single shot" mode worked as a good start.  I then change the filter type to "fixed" mode with 1/60 to 3/60th octave widths working well.  I will generally add only 2 or 3 filters set to "auto" mode to search for "roving" feedback.  The rest I set to "off" or do a little broad band equalization with a few to smooth out the speaker response.

I find using all of the filter available or letting them all all work in "single shot" or "auto" mode results in over equalization.  Once again, a few narrow filters set at the worst of the ring modes results in a noticeable increase in level and clarity and give good results.  1/3 octave equalizer filters are just to wide to work as effective feedback filters.  Narrow band or parametric filters, can "kill" the feed back and leave the audio intact.

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