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[Wes Thompson]

We had a lot of feedback issues too.  We solved it with the inexpensive Behringer feedback destroyer.  It is set up on my main mixer sub 1 and 2 with the left and right daisy chained for 24 channels of parametric eq.  I set up the FB with 18 channels of single shot eq and left the other 6 set to auto.  Once your single shot channels are set, that is where they stay.  The auto channels will auto-detect rings and knock them out.  This works really well with the lavs.  This unit helped a great deal with our choir mic setup too.  It has 10 presets so it can be "rung in" with different setups.  Once it was set up right, it has been "set and forget".

If you have the funding available, I would recommend a higher quality unit of course.  For 99 dollars the Behringer works quite well and we were pleasantly surprised by its performance.

-Wes

[Dick Rees]

I, too, have used the B******* FBX units, but they do take a bit of extra effort to use.

For the filters to remain stable once set you MUST switch them to parametric mode (PA).  Leaving them in single-shot (SI) mode WILL allow them to deepen and widen, eating program and thinning out the sound.  Unfortunately these must be switched per filter as there is no global way to lock them down as with the Sabine units.

I do like these (B******) units and use them on monitor duty when I end up there for a festival.  I do set up all ten available program memories in identical configs so I can simply switch to the next one without wiping the one I've just set up.  The filters are OK and if you know how to use one, they can be very good.  It's just that they are labor intensive with a bit of a steep learning curve.

The best solution although not the cheapest is the full-fledged Sabine GraphiQ.  With this unit you can do the whole system and the ability to see everything on a laptop is quite helpful.  Short of that, the Sabine Solo unit walks all over the Behringer.  I have and use both and that is my take on them:  both good, Sabine better.

[Wes Thompson]

I have a question for you Dick, but it does relate to this thread so I will keep it here.

So you say that the blocked frequencies will deepen and widen in single shot mode?  I never knew that.  So once the single shot filter is isolated do I just simply switch that filter over to parametric mode after that?

Do the filters deepen and widen constantly or is this unit effectively storing the deeper and wider settings?  In other words, when I power the unit up do the notches come up with the deeper and wider settings or do they come up with the original notch?

The reason I ask, every now and then the vocals can sound like they are in a tunnel.  I can switch to another preset and then back and it is fine after that. I figured that it is the auto filters that are causing this problem.

Do I have to re-ring the system for the offending frequencies again or can I simply switch the current single shot filters to parametric mode right after I turn the unit on?

Should I turn off the auto filters?  I don't think they are helping anyway since I will lower the channel gain faster than the FB will detect a ring anyway.

This unit has done wonders for improving the performance of our lavs.

Thanks,
Wes

[Dick Rees]

Wes Thompson wrote on Mon, 05 October 2009 09:05

I have a question for you Dick, but it does relate to this thread so I will keep it here. So you say that the blocked frequencies will deepen and widen in single shot mode?  I never knew that.  So once the single shot filter is isolated do I just simply switch that filter over to parametric mode after that?

That has been my experience.  Both the automatic (AU) and single-shot (SI) filters tend to "creep".  They keep analyzing the spectrum and adjusting themselves ad infinitum.  To be safe, just select the filters (one at a time since there is no global control) once they have identified a "hot" frequency and switch them to parametric (PA).  You can get pretty fast at this.  You can go back in and widen the filters manually (or deepen them) as needed once you've designated them as parametric.  FYI, there is a chart in the manual which will give you very specific frequency readings in +/- fashion from the default frequency centers.  For the skilled user this can be extremely handy in sonic micro-surgery.

Quote:

Do the filters deepen and widen constantly or is this unit effectively storing the deeper and wider settings?  In other words, when I power the unit up do the notches come up with the deeper and wider settings or do they come up with the original notch? The reason I ask, every now and then the vocals can sound like they are in a tunnel.  I can switch to another preset and then back and it is fine after that. I figured that it is the auto filters that are causing this problem.

You are correct, sir.  The changes will be permanent and do not require pressing the "Store" button.  You will be stuck with them.

Quote:

Do I have to re-ring the system for the offending frequencies again or can I simply switch the current single shot filters to parametric mode right after I turn the unit on?

If you've charted the initial settings after ringing out, you could switch to PA and then restore them by hand.  Otherwise it's back to square one.

[qoute]Should I turn off the auto filters?  I don't think they are helping anyway since I will lower the channel gain faster than the FB will detect a ring anyway.

This unit has done wonders for improving the performance of our lavs.

Thanks,
Wes[/quote]

I take it that you have left some previously unused filters lurking around in AU mode.  Typically, I'll set one of these units up with 5-7 filters set and locked down in PA mode, then turn off all but two of the remaining filters.  Those two I leave in AU mode as roving "safeties".  They will help catch transients, replace each other as needed and not generally yield the "cannibalistic" traits of a mass of AU or SI filters.

Yes, these units can function very, very well.  It took me a good while to come to the level of understanding necessary to utilize them fully.  Now that I do "grok" them fully, they can be very good.

Good luck.

DR

[Wes Thompson]

Excellent advice Dick.  I will re-ring the lavs and set the filters to parametric.  It is a pain to set up but once it is done it should be "set and forget".  

Feedback has been a constant struggle in our VERY live room and this unit has helped us tremendously in squeezing out more gain from the lavs.

The following is to add information on my feedback solution to this thread:

Have some helpers wear the lavs.  Run up the gain on each lav and use the parametric EQ on the mixer board to null out the main ring from each mic. Once you have achieved max gain with minimal ringing from each lav engage the FB with each filter in single shot mode and slowly raise the gain until you get a ring and a filter locks in on the ring. As soon as the filter locks in, switch it to parametric mode.  Once the gain is nice and strong have the lav helpers move around the speaking areas and see if the FB can lock on any more rings. Once most of the rings are filtered, leave only two channels set on auto mode and they can alternate to catch any transients.

One thing to note for anyone using one of these, it is important to have as close to 0db going through this unit as you can get without overdriving it.  It detects rings much better when you have a lot of gain going through it.

Thanks again Dick for giving me a better understanding of how to operate this unit.

-Wes

[Dick Rees]

Wes Thompson wrote on Mon, 05 October 2009 12:47

Excellent advice Dick.  I will re-ring the lavs and set the filters to parametric.  It is a pain to set up but once it is done it should be "set and forget".   Feedback has been a constant struggle in our VERY live room and this unit has helped us tremendously in squeezing out more gain from the lavs. The following is to add information on my feedback solution to this thread: Have some helpers wear the lavs.  Run up the gain on each lav and use the parametric EQ on the mixer board to null out the main ring from each mic. Once you have achieved max gain with minimal ringing from each lav engage the FB with each filter in single shot mode and slowly raise the gain until you get a ring and a filter locks in on the ring. As soon as the filter locks in, switch it to parametric mode.  Once the gain is nice and strong have the lav helpers move around the speaking areas and see if the FB can lock on any more rings. Once most of the rings are filtered, leave only two channels set on auto mode and they can alternate to catch any transients. One thing to note for anyone using one of these, it is important to have as close to 0db going through this unit as you can get without overdriving it.  It detects rings much better when you have a lot of gain going through it. Thanks again Dick for giving me a better understanding of how to operate this unit. -Wes

Wes....

I actually prefer to do my system corrections with all the channel EQ's flat (or disengaged), then do any remaining adjustments with the channel strips. That way you'll be getting a truer "read" of any room/system anomalies and reserving your individual channel EQ's for a less daunting task and simple tonal adjustments.

DR

[Don Sullivan]

The LS9 is a powerful mixer with plenty of tools to reduce feedback.If the 4 bands of parametric EQ on the input are not enough, you can use the 4 bands on the output as well, even if only during the message. In addition, try adding from 5 to 20 ms delay on the output. This can make a remarkable difference. Also, get the lav as close to the mouth as possible, even if it is just under the chin. If these steps aren't enough, consider moving the pastor back or the speakers forward or into a pair rather than a center cluster. ( personally, I despise center clusters   )

[Dick Rees]

Don Sullivan wrote on Sat, 10 October 2009 10:07

The LS9 is a powerful mixer with plenty of tools to reduce feedback.If the 4 bands of parametric EQ on the input are not enough, you can use the 4 bands on the output as well, even if only during the message. In addition, try adding from 5 to 20 ms delay on the output. This can make a remarkable difference. Also, get the lav as close to the mouth as possible, even if it is just under the chin. If these steps aren't enough, consider moving the pastor back or the speakers forward or into a pair rather than a center cluster. ( personally, I despise center clusters   )

Me three.

[Tim Padrick]

Non-politic answer: Tell the pastor that the feedback is owing to God's laws of physics, and that for situations such as this the E6 is God's answer to the problem.  He should man up and ease your burden by dealing with the extra little bit of almost nothing on his ear and use the E6.

[Steve Adams]

We were having the same issue with our Sennheiser lav. Feedback galore.

Our "fix" was an Ashley 31 band eq on the channel as an insert.

This took care of the feedback but the overall sound was less than 100% good quality.

Just this week we auditioned an AT over the ear mic very similar to the E6 (not sure of the AT model number right off) and we disconnected the insert eq and was able to use the 4 band channel eq on the board and this thing sounds GREAT!

I agree with a former poster and would suggest that the pastor take some of the load and wear the over the ear mic.

One suggestion (although some may call it mean, it would get your point across)

Set the eq for the lav so that every time the pastor opens his mouth he gets feedback. It won't take too long before he throws the thing across the sanctuary! Then you can say, "you won't get feedback with this E6..." I'm pretty sure he would be open to the idea of over the ear mics in that situation...

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