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[Dan Norman]

OK so my knowledge base is somewhat limited and need a little help.  A few years ago we put in Bose Panaray MA12ex loudspeakers.  Overall we have been happy with them, even though if I had it to do over again, I wouldn't.  Our pastor has a shure earworn mic.  Surprisingly we have very little feedback for the speaker to be right behind everyone.   The processor has a feedback suppressor (so I was told).  There have been a few times however, that with the pastors earworn, he has turned his head and coughed and turn right into the speaker.  A couple of weeks ago, as he was approaching the stage he stopped right in front of the speaker facing it to turn on his mic.  The feedback was tremendous.   When we have the big feedback moments it seems as if his mic becomes more sensitive and I get feedback more often.  The first time it happened we didn't use his earworn for several weeks, then we replaced the mic and it worked fine until a few weeks ago.  I have turned the gain down as far as I can go and still hear him.  Not sure what else to do. 

[Ivan Beaver]

"Feedback suppressors" can mean different things and operate differently.

Specific model numbers ALWAYS help when asking a question.

For example-imagine if you said: My car doesn't drive right-what is the problem"?

Some suppressors are locked out by the installer after installation, other have "floating points".  The problem with "floating points is that once they are "full" if a new freq is needed, one of the older ones is "dropped" and could have been really needed-so a new freq starts to feedback.

They are simply an eq point that puts a notch in the response at a freq that sustains a constant signal for a particular period of time.

DO NOT expect miracles from them.  They are intended for usage is a stable situation where they can act faster than a human hand/mind can.  NOT to put in a difficult situation and expected to fix system design problems.

The idea is not to rely on them, but to have available as a "quick grab" if needed.

Think of them as a air bag in your car.  It is far better to drive safe and apply the brakes, than to simply drive your car into a wall to stop-and hope the air bag keeps you alive.

[Mike Caldwell]

Ivan already summed up feedback suppressors for you.

With the big change in level you described my first thoughts are that a pad switch on the mixer channel has gotten turned off, the gain setting on the body pack transmitter has gotten changed or the output of the wireless receiver has been changed. Some receivers have mic / line switch on the back or a level control on the back, some are in a menu setting.

[Keith Broughton]

  A couple of weeks ago, as he was approaching the stage he stopped right in front of the speaker facing it to turn on his mic.  The feedback was tremendous.   

I don't care how much processing and anti-feedback magic the system has, opening a mic directly in front of a speaker is just asking for trouble!

[Mike Caldwell]

I don't care how much processing and anti-feedback magic the system has, opening a mic directly in front of a speaker is just asking for trouble!

And there is that!!

I have never been able to figure it out, you give someone a wireless mic and they always end up standing in front of a speaker!

[Ivan Beaver]

I don't care how much processing and anti-feedback magic the system has, opening a mic directly in front of a speaker is just asking for trouble!

And (not to be mean), but they "deserve" the "earfull" they get when doing so.

Maybe they will learn a lesson.

[Keith Broughton]

And (not to be mean), but they "deserve" the "earfull" they get when doing so.

Maybe they will learn a lesson.

They don't learn.
You know that Ivan 

[Stephen Swaffer]

No, they still look at the sound man- its his fault, naturally!

[g'bye, Dick Rees]

The problem is they use "faith-based physics".

[John Rutirasiri]

When we have the big feedback moments it seems as if his mic becomes more sensitive and I get feedback more often.  The first time it happened we didn't use his earworn for several weeks, then we replaced the mic and it worked fine until a few weeks ago.  I have turned the gain down as far as I can go and still hear him.  Not sure what else to do.

Following up on Ivan's comment (fixed vs. dynamic filters on the feedback suppressor): by your description, my suspicion is a good number of the filters are NOT fixed/locked.  When you have a massive feedback, the processor "releases" and goes through these dynamic filters rather fast -- dropping frequencies previously notched in an attempt to tame the new ones.  Now the system becomes "unstable" and more prone to feedback than before the feedback episode.

You should be able to check how many filters are fixed by looking at the front panel.  For example, on Sabine the fixed filter LEDs are solid red, while dynamic filters are blinking or different color.  You may have to set the numbers of fixed filters higher and leave just a couple of dynamic filters.  If you change the number of fixed filters, then you should run the feedback suppressor through the feedback detection/learning process again.

I would guess the problematic mic is the Pastor's (omni) headset mic.  You didn't mention what particular processor or feedback suppressor unit is installed and how it's being fed from the mixer.   If the feedback suppressor is a standalone unit, then you could have it as an insert on just the pastor's channel, which would make the feedback suppression more effective (filters not wasted on false freq).  If it's built into the loudspeaker processor/DSP like a Sabine Navigator or some Driveracks, then this might not be so easy.

Aside from "microphone best practices" session with the Pastor, whoever's manning the board has to be attentive and anticipate feedback when the Pastor walks in front of the FOH stack.  I would rather be late unmuting his channel/missing a couple of words than having a massive feedback.

John R.

[Keith Broughton]

The problem is they use "faith-based physics".

Good one 

Where is the speaker system located and why is the pastor in front of it?
I must admit, I'm not a fan of auto feedback processing at all, but especially on moving mics.
Would probably work great for a pulpit mic.

I looked up the specs and a bunch of 2.5" drivers with "145° horizontal x 20° nominal coverage". At what frequency?

[Chrysander 'C.R.' Young]

I read the tech manual on this speaker and it is essentially omni below 1kHz!

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