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Title: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 22, 2014, 11:55:26 PM
I am the head of the AV Crew at my church and we're looking to add a feedback eliminator to our modest gear.  We're currently looking at the dbx DriveRack PA+ that we can get for under $500 that also includes an auto EQ feature.  Anybody have any experience with this unit or other suggestions?

For background, we have a pretty simple setup.  We recently rewired the main speakers, added an amplifier, and adjusted the gain structure from the microphones to the amplifiers.  The results were even better than we could have anticipated.  Now the speakers actually have some bass response to the point that I had to dial it back on the board.  A big service for us would be six microphones for singers and a couple of guitars, the most common setup is just four singers.

Any advice would be appreciated.  The AV Crew is mostly made up of engineers, but none of us have any previous AV experience so are learning as we go.  I think we've made great strides in the past few months, but there's always more to learn.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Corey Scogin on April 23, 2014, 12:09:44 AM
Don't use a feedback eliminator or the auto EQ feature on the Driverack.  They tend to cause more problems.

I assume you are having feedback issues with the vocal mics.

A 31-band EQ inserted on the mains or monitor bus (1 eq channel for each bus channel of course) will allow you cut the offending frequencies and increase the gain-before-feedback of your vocal mics. That same EQ can also be used to adjust the overall EQ of the system if needed to dial back the bass you mentioned.  A Driverack will work just as well or better for that but manually adjust it, don't use the Auto-EQ feature.  If using the DriveRack, you may want to use the PEQ's instead of the GEQ's.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Ivan Beaver on April 23, 2014, 07:45:44 AM
feedback eliminators work best when inserted on a troublesome channel-NOT on the whole mix.

When they are on the whole mix-they will affect the freq response of everything-NOT just the mic causing the issue.

Different mics in different places will feedback at different freq-so they will all get affected in a neg way when on the mains.

Now if there is only ONE source of sound (say the pulpit mic) and no other inputs into the system (mics or line signals) then you can use it on the mains.

But otherwise it is advisable not to.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Steve M Smith on April 23, 2014, 08:22:17 AM
I agree with Corey.  For a fixed installation, use a 31 band equaliser on each output and tune it by ear (do a search for ringing out).

The resonance of the room isn't going to change unless you do some drastic rennovations.


Steve.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on April 23, 2014, 12:15:15 PM
I agree with Corey.  For a fixed installation, use a 31 band equaliser on each output and tune it by ear (do a search for ringing out).

The resonance of the room isn't going to change unless you do some drastic rennovations.


Steve.

Agree as well.

The problem lies in the expectations raised by the term "feedback exterminator".  The proper way to approach the "problem" is to  properly set up the system in the first place such that you have the maximum headroom from the system within the room/environment. 

A more proper way to think of the use for such devices should be "automatic parametric EQ".  By considering it as an EQ rather than an exterminator, it should be much clearer that any issues of headroom, GBF and/or system tuning and deployment should be done BEFORE feedback becomes a problem.

FBX units do have their uses, but in order for them to be of practical use one should understand why and how feedback occurs and how to avoid it with the "ounce of prevention" rather than trying to address it with a "pound of cure".       
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Ivan Beaver on April 23, 2014, 12:33:57 PM
Agree as well.

The problem lies in the expectations raised by the term "feedback exterminator".  The proper way to approach the "problem" is to  properly set up the system in the first place such that you have the maximum headroom from the system within the room/environment. 

A more proper way to think of the use for such devices should be "automatic parametric EQ".  By considering it as an EQ rather than an exterminator, it should be much clearer that any issues of headroom, GBF and/or system tuning and deployment should be done BEFORE feedback becomes a problem.

FBX units do have their uses, but in order for them to be of practical use one should understand why and how feedback occurs and how to avoid it with the "ounce of prevention" rather than trying to address it with a "pound of cure".     
YES

Manufacturers LOVE people who want a nice simple solution-no matter if it is the wrong one or does not work as well as a the RIGHT solution.

Proper design/setup of the system is KEY.  And when that is done-something like a feedback eliminator can be helpful in some cases for the "quick got out of hand" type thing.

But as we all know- it is real easy for those type devices to totally wreck the sound quality.  But as long as the mic is not feeding back-then they have "done their job".

Why bother singing on key when we have autotune?  BECAUSE it SOUNDS better----------

The right solution costs more-but in the end is better.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 23, 2014, 03:00:42 PM
Thank you for the information.  We very rarely have a significant issue with feedback and we are looking at the unit as more of a backup than a solution.  The past week was only the second week after we completely changed the system setup and the first week where we got more than one praise song and the pastor spoke (the first week was a video presentation).  We had some low level feedback that several of us were trying to isolate.  I wasn't running the board but wandered that direction to see if we could figure anything out.  Another one of the crew noticed that several of the singers were absent mindedly pointing their microphones at the mains above them and even worse dropping the mics and pointing them at the monitors.

Just this week I have started a "campaign" get encourage proper use of the microphones so this may solve 99% of the problems we have IF people will follow through.  I just thought the feeback eliminator and auto EQ might prevent the rare unexpected feedback event.  I assumed they functioned in an active live mode, but it appears that once it sets a filter that frequency is locked until it is reset.  This isn't really what I had in mind.

Several months ago we had one major event that hasn't happened again and we couldn't figure out what happened.  Two wireless microphones were involved and when the two people got close to each other the feedback went through the roof.  We hadn't changed anything from previous weeks and didn't change anything after so it must have been a combination of unlikely factors.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jonathan Johnson on April 23, 2014, 05:47:15 PM
I'll have to agree with Dick & Ivan. Dick's description of a feedback eliminator as an "automatic parametric equalizer" is spot-on -- that's exactly what it is. The most common feedback frequencies will be due to room resonances, which will be present even without feedback. The proper (but debatable) way to address this is with FIXED parametric EQ on the mains tuned to those resonant frequencies.

Once you've tuned the room, any other offending feedback will usually be due to the microphone's position relative to the speakers. Change the location of the microphone and the frequency will change. You may want to notch out that frequency, but you really don't want to apply that to other channels. (Especially if the feedback frequency is 440Hz.  :o ) As the microphone moves, the chance of feedback at that frequency disappears, so that filter can be discarded. (The problem with feedback eliminators is that filters may be retained long after they are no longer needed.)

When applied to the mains, a feedback eliminator can lock onto desired frequencies that are most definitely not feedback, such as sustained musical notes from instruments. That is a bad situation and makes the mix sound awful.

A feedback eliminator can be a useful tool, but it should be considered a tool of last resort and be applied only as a per-channel insert. (That means you'd have to install a separate feedback eliminator for each vocal channel! And four units at $500 isn't a cheap solution anymore.) Your first tools should be proper selection and placement of loudspeakers to keep the stage out of the coverage pattern and educating your talent on the proper use and handling of microphones INCLUDING how to position them relative to stage monitors, based on the microphone's pickup pattern.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 23, 2014, 09:09:01 PM
I do appreciate the information. Along with this forum I emailed someone at the conference level in my church and they put me in touch with their "expert" and he emailed me today. He offered to come out and see/hear the system so that may be turn into a great resource.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Tom Bourke on April 24, 2014, 01:08:22 AM
Thank you for the information.  We very rarely have a significant issue with feedback and we are looking at the unit as more of a backup than a solution.  The past week was only the second week after we completely changed the system setup and the first week where we got more than one praise song and the pastor spoke (the first week was a video presentation).  We had some low level feedback that several of us were trying to isolate.  I wasn't running the board but wandered that direction to see if we could figure anything out.  Another one of the crew noticed that several of the singers were absent mindedly pointing their microphones at the mains above them and even worse dropping the mics and pointing them at the monitors.

Just this week I have started a "campaign" get encourage proper use of the microphones so this may solve 99% of the problems we have IF people will follow through.  I just thought the feeback eliminator and auto EQ might prevent the rare unexpected feedback event.  I assumed they functioned in an active live mode, but it appears that once it sets a filter that frequency is locked until it is reset.  This isn't really what I had in mind.

Several months ago we had one major event that hasn't happened again and we couldn't figure out what happened.  Two wireless microphones were involved and when the two people got close to each other the feedback went through the roof.  We hadn't changed anything from previous weeks and didn't change anything after so it must have been a combination of unlikely factors.
When you don't know the cause is exactly when they can do the most damage.  Often they are used as an electronic solution to a physical problem.  An auto EQ can not see the stage or know what is going on.  That also raises another issue, a feed back destroyer and auto EQ as implemented by DBX are different processes.  If you don't understand the underlying process you will not know when or how to temper them.

Almost every time I have encountered feedback processors in an installed system I have improved things just by eliminating them.  The very few notable examples have been where they were used as very precise parametric notch filters and the auto functions turned off.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 26, 2014, 10:40:01 PM
Today, we had a great example of how clean the current sound is. Special music was a solo singer accompanied by an accoustic guitar. The sound level on the guitar was a little lower than what I would have had it, but it was so clean that it was difficult to tell if the microphone was on at all. In the past it would have been painfully obvious.

The sermon portion of the service was a congregational discussion using multiple wireless microphones. This is always a challenge because the sound booth is in the balcony making it impossible to track the microphones. The best solution is to leave all the microphones open. Normally, it doesn't have any real consequences, but today we had some low level feedback coming through. My brother-in-law spent a few minutes at the board trying to EQ it out and had some success. In the past the noise level in the system may have almost comet sly covered it up.

Any thoughts on using the DriveRack in a more manual mode for an EQ?  Any other product suggestions in the $500 range?  We have a very limited budget such that if it is working we don't often make changes. I donated the new amplifier because I wanted it and as it turns out it really wasn't needed on we were able get things setup correctly.

Any suggestions for just an EQ with some semi automatic method for setup?  I am not sure any of us would have much success doing it just by ear.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: David Sturzenbecher on April 26, 2014, 11:26:53 PM
Today, we had a great example of how clean the current sound is. Special music was a solo singer accompanied by an accoustic guitar. The sound level on the guitar was a little lower than what I would have had it, but it was so clean that it was difficult to tell if the microphone was on at all. In the past it would have been painfully obvious.

The sermon portion of the service was a congregational discussion using multiple wireless microphones. This is always a challenge because the sound booth is in the balcony making it impossible to track the microphones. The best solution is to leave all the microphones open. Normally, it doesn't have any real consequences, but today we had some low level feedback coming through. My brother-in-law spent a few minutes at the board trying to EQ it out and had some success. In the past the noise level in the system may have almost comet sly covered it up.

Any thoughts on using the DriveRack in a more manual mode for an EQ?  Any other product suggestions in the $500 range?  We have a very limited budget such that if it is working we don't often make changes. I donated the new amplifier because I wanted it and as it turns out it really wasn't needed on we were able get things setup correctly.

Any suggestions for just an EQ with some semi automatic method for setup?  I am not sure any of us would have much success doing it just by ear.

It sounds like what you need may be an auto mixer.  Simplified, it will only allow for one microphone to be on, automatically.  If one person is talking, they get the full level, and all other mics are muted.  If two people are talking, they share the equivalent level of one mic.  Essentially, muting microphones not in use.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Michael A. Yates on April 27, 2014, 10:54:06 AM

Don't use a feedback eliminator or the auto EQ feature on the Driverack.  They tend to cause more problems.

I assume you are having feedback issues with the vocal mics.

A 31-band EQ inserted on the mains or monitor bus (1 eq channel for each bus channel of course) will allow you cut the offending frequencies and increase the gain-before-feedback of your vocal mics. That same EQ can also be used to adjust the overall EQ of the system if needed to dial back the bass you mentioned.  A Driverack will work just as well or better for that but manually adjust it, don't use the Auto-EQ feature.  If using the DriveRack, you may want to use the PEQ's instead of the GEQ's.

+1


Sent from my iPad using Tapatalk
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 27, 2014, 04:40:08 PM
Is part of the problem with the auto EQ related to the single point measurement in a large venue with varied acoustics?  I am familiar with home audio auto setup that have multiple locations in the measurement and the use an algorithm to optimize. My church is certainly larger than a home theater setting, but reasonably small on a church scale.

If we were to get a 31 band graphic EQ what is the best way to set it up?  Pink noise with some type of measurement throughout the church to identify hot spots to be eliminated?
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on April 27, 2014, 04:45:37 PM
Is part of the problem with the auto EQ related to the single point measurement in a large venue with varied acoustics?  I am familiar with home audio auto setup that have multiple locations in the measurement and the use an algorithm to optimize. My church is certainly larger than a home theater setting, but reasonably small on a church scale.

If we were to get a 31 band graphic EQ what is the best way to set it up?  Pink noise with some type of measurement throughout the church to identify hot spots to be eliminated?

I have a PDF primer on this.  Send me an Email address via PM and I'll send it to you.  PDF's cannot be attached to PM's.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 29, 2014, 03:11:32 PM
Thank you dick reese for the primer.

I have been discussing what I'm learning with some of the other guys on the AV Crew and I think the final decision will still be to go with the dbx Driverack PA+ with the knowledge that using the Auto-EQ and Feedback Supression has limits and may prove to be a poor solution.

One reason that we are planning to go this direction is that it includes 28 band graphic EQ that we can setup manually if we are not satisfied with the Auto-EQ.  I looked at several of the 31 band EQ units and even though the physical sliders would make setup easier than dealing with the menus and such, we think that it would be far to tempting/easy for people to tinker with it.  The sound equipment isn't isolated to prevent people from messing with it, it's used on occasion by people that are not on the AV Crew for small events during the week, and we rent to two other churches.  The reality is that we often find things like the amplifier levels adjusted.  I wish we had a little more control over things, but without a significant financial investment and/or being willing to run AV for the other churches this is where we are at.

The feedback elimination has a lot of setup options that should give us a reasonable chance of success, or at least avoid making things worse.  Our praise teams never practice with us we we're always reacting on the fly and the vast majority of the people using the microphones refuse to hold them correctly (we're working on this).  We think there are things that will happen that just having a perfectly EQ'd system may not account for.  As an example, a couple of weeks ago one of the singers dropped their microphone and pointed it directly into the monitor.  If the results are not positive, then we can disable the feedback circuit and rely on the EQ.

We're hopeful that we can eliminate the majority of the feedback issue with the EQ (auto or manual) and can then just rely on the feedback elmination for the unstoppable events that are sure to happen.

The Driverack has lift setting so that we can release the filter after 5 seconds or hold them up to 60 minutes in the live mode.  It seems that lifting the filters sooner rather than later should better maintain sonic integrity.  We can also set it up to use faster acting wider filters (i.e. speech) or slower acting narrow  filters (high music).  I would suspect that we should be able to find a reasonable balance between the sensitivity and the lift time to yield unobtrusive results.

Our goal is quality sound without feedback and we're most of the way there.  Our sound quality is great, we have plenty of volume so we don't need to get every last ounce out of the system, but we need to get the feedback under control.  The dual purpose unit should give us options for an affordable price.

Any thoughts on a good starting combination for the feedback sensitivity (not the right word I know) and lift times?
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on April 30, 2014, 10:23:00 AM
Thank you dick reese for the primer.

I have been discussing what I'm learning with some of the other guys on the AV Crew and I think the final decision will still be to go with the dbx Driverack PA+ with the knowledge that using the Auto-EQ and Feedback Supression has limits and may prove to be a poor solution.


Sorry to hear that, Jon.  The DR will not substitute for learning and understanding.  It will make the same idiotic mistakes over and over again.  It can't learn.  The only thing it can substitute for is human inexperience and ineptitude.

Every journey begins with a single, sure step.  If you do not take that first step, you'll never get anywhere.  The DR is the wrong step.

I would suggest you use the DR strictly for speaker processing, then add an analog EQ between it and the mixer.  One you derive proper settings by using the method in the primer, transfer them to the EQ in the DR and lock them down securely.  This will take care of the standing wave/room mode issues.  You can then use the analog EQ for tonal adjustments of the overall mix.  This uses each piece to the optimum level.

Trying to use the DR as you describe will be "treading water" forever....and you'll swallow a lot of water in the process.  Better to bite the bullet, learn and apply the proper methods and spread the knowledge through your volunteer base.

 
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 30, 2014, 12:48:09 PM
Sorry to be "that guy" that asks for advice and then ignores it.  I have learned a lot in my short time on the forum and I certainly don't think that I know better than you.  I'm looking at the DR as the next step.  At worst it will give us a 28-band EQ that should be adequate for doing a proper room EQ and at best it may resolve our issues.

Are products like the DR primarily intended for temporary quick setup venues (that seems to be where a lot of the positive reviews come from) or do you consider it a gimmick in general?  If the feedback eliminator functions were turned off, is it safe to assume that we shouldn't have any negative sonic effects?

I hope you're still willing to give me some advice as to where either the DR or a graphic EQ should be put into the system.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: TJ (Tom) Cornish on April 30, 2014, 01:30:02 PM
Sorry to be "that guy" that asks for advice and then ignores it.  I have learned a lot in my short time on the forum and I certainly don't think that I know better than you.  I'm looking at the DR as the next step.  At worst it will give us a 28-band EQ that should be adequate for doing a proper room EQ and at best it may resolve our issues.

Are products like the DR primarily intended for temporary quick setup venues (that seems to be where a lot of the positive reviews come from) or do you consider it a gimmick in general?  If the feedback eliminator functions were turned off, is it safe to assume that we shouldn't have any negative sonic effects?

I hope you're still willing to give me some advice as to where either the DR or a graphic EQ should be put into the system.
John, the Drive Rack PA series is in the vein of a Leatherman multi-tool.  It's a lot cheaper than buying the all of the tools it contains, but no one does much real work with a Leatherman screwdriver.

In the hands of someone who knows what they are doing, a graphic EQ can be useful, and the one that's in the DRPA is fine.  The problem is the general thinking - a magic $500 box will make everything better, and tools like the "auto-EQ" "room tuning wizard" mean you don't need to know what you are doing to use it.

As was said earlier in the thread, a feedback buster doesn't belong on the main sends or in the speaker processor.  As a channel or group insert - fine.  Over the whole system - no.

The secondary problem with Drive Rack PA devices is that once the user figures out that the box isn't as useful as marketing info claims, you find out that the tools you really need - alignment delay, etc., are insufficient in the PA series, and you have to throw it away and start over.


A proper room EQ starts with hiring a person with measurement skill to come and using a combination of EQ, delay, speaker placement, and knowledge of how to interpret the results, comes up with a system tuning suitable for your purpose.  For a fixed install, this tuning should be done in a DSP device (and it's possible the DRPA+ may be good enough, but possibly not), that's locked so later help doesn't come in and try to "improve" it.  At this point, if feedback issues are still present, now you may choose to use a feedback buster, or other methods like moving speakers, changing mic type, etc.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on April 30, 2014, 01:56:20 PM
John, the Drive Rack PA series is in the vein of a Leatherman multi-tool.  It's a lot cheaper than buying the all of the tools it contains, but no one does much real work with a Leatherman screwdriver.

In the hands of someone who knows what they are doing, a graphic EQ can be useful, and the one that's in the DRPA is fine.  The problem is the general thinking - a magic $500 box will make everything better, and tools like the "auto-EQ" "room tuning wizard" mean you don't need to know what you are doing to use it.

As was said earlier in the thread, a feedback buster doesn't belong on the main sends or in the speaker processor.  As a channel or group insert - fine.  Over the whole system - no.

The secondary problem with Drive Rack PA devices is that once the user figures out that the box isn't as useful as marketing info claims, you find out that the tools you really need - alignment delay, etc., are insufficient in the PA series, and you have to throw it away and start over.


A proper room EQ starts with hiring a person with measurement skill to come and using a combination of EQ, delay, speaker placement, and knowledge of how to interpret the results, comes up with a system tuning suitable for your purpose.  For a fixed install, this tuning should be done in a DSP device (and it's possible the DRPA+ may be good enough, but possibly not), that's locked so later help doesn't come in and try to "improve" it.  At this point, if feedback issues are still present, now you may choose to use a feedback buster, or other methods like moving speakers, changing mic type, etc.

Well said.  Equally a potential waste of time AND money.

The user interface for such multi-purpose boxes is a real handicap for folks with your proposed application, Jon.  And by the time you've learned how to make it even marginally functional, you could likely train your whole team to do it quicker and better.

That's what the primer is for.  It should take anyone who can follow directions far less time to implement an acceptable EQ job with an analog graphic than to hack it up with the DR.  I'll venture that even the first attempt with the BTI method will be lightyears ahead of the DR EQ.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 30, 2014, 05:01:23 PM
We have not made the purchase yet so there's still hope for us going a different direction.  Let me give a description of our current setup.

The two main Electro-Voice FRX-640 speakers are located about 22 above the center of the platform, these two speakers are powered by EP2500 amplifiers in bridged mode.  There are four small speakers mounted under the balcony that are being powered on one channel of an EP2000 amplifier.  The second channel on the EP2000 amplifier is powering the two stage monitors.  Our board is a Midas Venice 240 and that is currently feeding into a Electro-Voice Dx38 24 BIT DIgital Sound System Processor.  The #1 input on the Dx38 is feeding the two main speakers (Outs #1 & #2) and the four under balcony speakers (Out #4) and the #2 input is feeding the monitors (Out #3).  Currently, the only processing being done by the Dx38 is a delay on the under balcony speakers.  It looks like it has a 5-band PEQ that might be enough to eliminate the majority of the offending frequencies.  We normally use 6 Sennheiser 100 series wireless microphones and often only four of them are used for praise singing with the occasional guitar or two.  Praise time is almost always done in the same general area and announcements are done front and center.  The sanctuary is in the range of 40 feet deep and maybe 60 feet wide.  Our issues with feedback generally result from people using the microphones incorrectly (we're trying  to educate but have little hope for success) or when several of the microphones are used to roam the sanctuary under the balcony that is out of view pretty much forcing us to leave them open.

Would you feel better about us purchasing something like the dbx iEQ 31 Equalizer?  Or should we just go bare bones with something like the DOD SR231QX Graphic Equalizer?
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on April 30, 2014, 05:41:16 PM
We have not made the purchase yet so there's still hope for us going a different direction.  Let me give a description of our current setup.

The two main Electro-Voice FRX-640 speakers are located about 22 above the center of the platform, these two speakers are powered by EP2500 amplifiers in bridged mode.  There are four small speakers mounted under the balcony that are being powered on one channel of an EP2000 amplifier.  The second channel on the EP2000 amplifier is powering the two stage monitors.  Our board is a Midas Venice 240 and that is currently feeding into a Electro-Voice Dx38 24 BIT DIgital Sound System Processor.  The #1 input on the Dx38 is feeding the two main speakers (Outs #1 & #2) and the four under balcony speakers (Out #4) and the #2 input is feeding the monitors (Out #3).  Currently, the only processing being done by the Dx38 is a delay on the under balcony speakers.  It looks like it has a 5-band PEQ that might be enough to eliminate the majority of the offending frequencies.  We normally use 6 Sennheiser 100 series wireless microphones and often only four of them are used for praise singing with the occasional guitar or two.  Praise time is almost always done in the same general area and announcements are done front and center.  The sanctuary is in the range of 40 feet deep and maybe 60 feet wide.  Our issues with feedback generally result from people using the microphones incorrectly (we're trying  to educate but have little hope for success) or when several of the microphones are used to roam the sanctuary under the balcony that is out of view pretty much forcing us to leave them open.

Would you feel better about us purchasing something like the dbx iEQ 31 Equalizer?  Or should we just go bare bones with something like the DOD SR231QX Graphic Equalizer?


the DX38 is head and shoulders above the DR.  You already have the gear you need, so don't waste any money on more.  What you need to do is find a competent system tech to go through things with/for you, pay them to set it up properly and have them give you the short course in the "how-to's".

Groping, guessing and looking for "magic beans" to purchase will cost you a lot more than hiring a competent professional to assist you, both in money and frustration.

DIY without experience is very, vey expensive.

Hire help.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 30, 2014, 10:15:23 PM
Do you think it would be worth picking up a 31 band EQ on the cheap just for use ringing out the room and then transfer the settings for the offending frequencies to the Dx38?

There is a used unit at B&H for under $100. Was tempting. Since I am not spending my own money I can't just pull the trigger.  Seems like doing the setup with a parametric EQ hidden in the menus would be a lot more effort.

I may have a friend with one that I can just borrow.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on April 30, 2014, 10:21:14 PM
Do you think it would be worth picking up a 31 band EQ on the cheap just for use ringing out the room and then transfer the settings for the offending frequencies to the Dx38?


No.

Hire competent help.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: David Sturzenbecher on April 30, 2014, 10:31:33 PM
Jon,
If you post you location someone here may be able to help you out. 


Sent from my iPhone using Tapatalk
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on April 30, 2014, 11:07:02 PM
Jon,
If you post you location someone here may be able to help you out. 


Sent from my iPhone using Tapatalk

I may have a resource already through the church, but I'm on the opposite side of the Puget Sound from Seattle.  If you're in the area you'll know what I'm talking about.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Corey Scogin on April 30, 2014, 11:24:01 PM
Do you think it would be worth picking up a 31 band EQ on the cheap just for use ringing out the room and then transfer the settings for the offending frequencies to the Dx38?

If you're planning to tune the system yourself, I'd just learn how to quickly adjust the DX38's parametric EQ.  The 31-band GEQ settings will not easily translate to a PEQ.  Sounds like all you need is a measurement microphone, interface, and an RTA to get started.

As Mr. Rees mentioned already, hiring someone to tune the system and walk you through the process will be money well spent.  Definitely worth more than a DriveRack PA.

...I'm on the opposite side of the Puget Sound from Seattle.
I'm not an expert by any means but if you'll fly my wife and I up from Alabama, I'll be glad to help you out!  I'd like to visit the NW.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Ivan Beaver on May 01, 2014, 06:29:28 AM
Do you think it would be worth picking up a 31 band EQ on the cheap just for use ringing out the room and then transfer the settings for the offending frequencies to the Dx38?

There is a used unit at B&H for under $100. Was tempting. Since I am not spending my own money I can't just pull the trigger.  Seems like doing the setup with a parametric EQ hidden in the menus would be a lot more effort.

I may have a friend with one that I can just borrow.
Not to be "picky" but how were you planning on coming up with the "numbers" to enter into the DSP?

By looking at the front panel of graphic and "hoping" that the silk screened number on the graphic are remotely correct?

Good luck with that.

It appears as if you keep trying your best to do it the wrong way and somehow hoping you will get lucky enough to somehow get close enough?

That is a long shot at best.

Aligning a sound system is not a "guessing game".  At least to do it right.

And if feedback is is a cocnern-then a good alignment (not "ringing out" the room) is the best starting point.

Sorry.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Steve M Smith on May 01, 2014, 02:21:20 PM
If you buy a 31 band EQ and ring out the room with it - just leave it connected.


Steve.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on May 01, 2014, 02:28:48 PM
Not to be "picky" but how were you planning on coming up with the "numbers" to enter into the DSP?

By looking at the front panel of graphic and "hoping" that the silk screened number on the graphic are remotely correct?

Good luck with that.

It appears as if you keep trying your best to do it the wrong way and somehow hoping you will get lucky enough to somehow get close enough?

That is a long shot at best.

Aligning a sound system is not a "guessing game".  At least to do it right.

And if feedback is is a cocnern-then a good alignment (not "ringing out" the room) is the best starting point.

Sorry.

Yup.

After all the bits and pieces have been presented, it would seem that the system was well installed and likely tuned competently given the config and gear involved.  What appears to be the issue is the inability or lack of interest by the participants to learn proper technique and system use.

IOW...OE.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on May 01, 2014, 10:15:12 PM
I thought someone had suggest led transferring the EQ from the graphic to a parametric EQ in an earlier post. Was just thinking more about trying to do it ourselves.

While the previous people may have purchased quality gear, it was never setup correctly as we have not undone anything that didn't need to be corrected.  The speakers were clearly hooked up incorrectly.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on May 02, 2014, 05:24:37 AM
I thought someone had suggest led transferring the EQ from the graphic to a parametric EQ in an earlier post.

It was suggested to transfer GEQ to GEQ, not to PEQ.  "Ringing out" is much more easily done on an analog EQ with physical sliders than the consarned digital in the DRack...
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: John Woodfield on May 02, 2014, 02:13:23 PM
It was suggested to transfer GEQ to GEQ, not to PEQ.  "Ringing out" is much more easily done on an analog EQ with physical sliders than the consarned digital in the DRack...

+1
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jerome Malsack on May 02, 2014, 05:39:22 PM
One could always hit the power switch to off !
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on May 05, 2014, 08:46:04 PM
It was suggested to transfer GEQ to GEQ, not to PEQ.  "Ringing out" is much more easily done on an analog EQ with physical sliders than the consarned digital in the DRack...

Got it.

I was at a sister church this past week that had a professional EQ done in recent weeks so I was able to talk to the sound guy about his experience.  It was done by the person that I was recommended to talk to.

Is there any recommendations for a 31 band GEQ that doesn't have the sliders that are so easy to mess with?  It seems like someone would produce a unit with a manual lock of some type.  I think it would be beneficial to have more than a 5 band PEQ to fully benefit from a professional setup?
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Corey Scogin on May 05, 2014, 08:57:37 PM
Is there any recommendations for a 31 band GEQ that doesn't have the sliders that are so easy to mess with?  It seems like someone would produce a unit with a manual lock of some type.  I think it would be beneficial to have more than a 5 band PEQ to fully benefit from a professional setup?

I would take a 5 band PEQ over a 31-band GEQ any day as long as the PEQ has adjustable bandwidth. You have what you need in the Dx38.

I was at a sister church this past week that had a professional EQ done in recent weeks so I was able to talk to the sound guy about his experience.  It was done by the person that I was recommended to talk to.

Did you talk to that recommended professional?  What do they think?  If you're going to call them to come in and tweak your system, you'll want to hold off on any purchases until they say otherwise.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on May 05, 2014, 08:58:34 PM
Got it.

I was at a sister church this past week that had a professional EQ done in recent weeks so I was able to talk to the sound guy about his experience.  It was done by the person that I was recommended to talk to.

Is there any recommendations for a 31 band GEQ that doesn't have the sliders that are so easy to mess with?  It seems like someone would produce a unit with a manual lock of some type.  I think it would be beneficial to have more than a 5 band PEQ to fully benefit from a professional setup?

Sabine GraphiQ...without a doubt.  I use the single rack space 2 channel units.  No panel controls, strictly PC GUI.  Three levels of access so you can keep the noobs limited to on/off.

The models with front panel controls are more rack spaces, but you can use the physical controls OR disable them and limit access to users with a password via PC.  I think this fills all your requirements.

Look it up at the Sabine website.  Two channels of 31 band GEQ with variable filter width(!), 12 PEQ/channel.  PEQ filters can auto-set and lock or set as dynamic...or you can just choose manual PEQ mode.

You really should check them out.  I find them used for under $200.00.

Check your PM's.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Hanno Meingast on May 05, 2014, 11:25:27 PM
Sabine GraphiQ...without a doubt.  I use the single rack space 2 channel units.  No panel controls, strictly PC GUI.  Three levels of access so you can keep the noobs limited to on/off.

The models with front panel controls are more rack spaces, but you can use the physical controls OR disable them and limit access to users with a password via PC.  I think this fills all your requirements.

Look it up at the Sabine website.  Two channels of 31 band GEQ with variable filter width(!), 12 PEQ/channel.  PEQ filters can auto-set and lock or set as dynamic...or you can just choose manual PEQ mode.

You really should check them out.  I find them used for under $200.00.

Check your PM's.

+1 on the sabine.  It sounds like your problems are mostly with the roving wireless mics.
how about putting the mics on a subgroup and inserting the EQ on that group only

Hanno
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on May 13, 2014, 02:55:07 PM
I've been really busy recently and distracted from this project, but thought that I should provide an update.  If you're familiar with the term "askhole" I'm trying to avoide it applying to me.

I did call the local professional and got a quote ($400) for coming out and doing a full setup.  He also recommended that we consider a Symetrix Jupiter 4 ($1,000) for our application.  We had a long discussion about how the monitors, under balcony speakers, and main speakers all needed to have a different EQ to achieve the best results.

At this point I'm working with the rest of the AV Team to evaluate our options.  I know that the Church Board would approve the $1,400 (because they trust us) so it's important that the AV Team have consensus on the best solution.  My personal feeling is that I would prefer to have something with more flexibility than the Dx38 if we are going to spend the money to have a professional setup done.  I think I may have to contact the person that previously helped setup the system in my church originally to see if he still has the equipment and willingness to help.  I am not sure what his level of skill really is, but it shouldn't cost anything to find out.

I'll take another look at the Sabine GraphiQ.

Thanks again for the ideas and information.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Garrett Nelson on May 14, 2014, 09:38:41 PM
I always put these over EQs I install:

http://www.parts-express.com/middle-atlantic-sf1-perforated-security-rack-cover-1u--262-460

It keeps people from messing with them.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Arnold B. Krueger on May 15, 2014, 10:22:38 AM
I've been really busy recently and distracted from this project, but thought that I should provide an update.  If you're familiar with the term "askhole" I'm trying to avoide it applying to me.

I did call the local professional and got a quote ($400) for coming out and doing a full setup.  He also recommended that we consider a Symetrix Jupiter 4 ($1,000) for our application.  We had a long discussion about how the monitors, under balcony speakers, and main speakers all needed to have a different EQ to achieve the best results.

At this point I'm working with the rest of the AV Team to evaluate our options.  I know that the Church Board would approve the $1,400 (because they trust us) so it's important that the AV Team have consensus on the best solution.  My personal feeling is that I would prefer to have something with more flexibility than the Dx38 if we are going to spend the money to have a professional setup done.  I think I may have to contact the person that previously helped setup the system in my church originally to see if he still has the equipment and willingness to help.  I am not sure what his level of skill really is, but it shouldn't cost anything to find out.

I'll take another look at the Sabine GraphiQ.

Thanks again for the ideas and information.

I spent about 12 years running live sound in a church that had a very dated design that lacked many of the architectural features that tend to reduce a room's susceptibility to feedback.  Heck, about half of the main speaker cluster was almost boresighted on the area that eventually became our band/orchestra pit, and that is just an example. Of course the church board was stagnant on many more pressing issues, so the sound system never received serious attention, either.

However I was able to sneak in a little technology both in terms of mics and electronics, and my tour of duty was characterized by other experienced mixers from larger churches in the area including some of my predecessors as being generally clear, well balanced and pleasant.

After looking at the DX38 it does not seem to lack the sum and substance of the electronic tools that I used to do what I did. What it does seem to lack is an easy user-oriented interface.

The idea of augmenting a well-adjusted and locked down DX 38 with something that has easy-to-twirl knobs has a lot of romance.

I will fearlessly countermand those who recommend against parametric eq. I've used both graphic and parametric eq, and if there are enough bands a graphic eq can work. But given the choice, I'd pick a multiband parametric first, just about every day of the week. 4 bands minimum, 6 wouldn't be wasted.

Live sound systems being necessarily dynamic in these days, adaptability. Electronic approaches to feedback reduction are necessarily intimately tied to a certain configuration of microphones. Move one several feet or even reorient it, and its time to retune the notches.

The best antifeedback tool is an experienced operator with the appropriate tools. This includes both equalizers and a collection of mics and stands and knowledge about how and motivation to use them. From the standpoint of the mixing console, the most effective tool is muting the mics that aren't relevant to the current scene.

Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: g'bye, Dick Rees on May 15, 2014, 11:53:18 AM



After looking at the DX38 it does not seem to lack the sum and substance of the electronic tools that I used to do what I did. What it does seem to lack is an easy user-oriented interface.
[/quote

The RACE software allows you to use a computer to easily adjust and set up all parameters without scrolling/paging through the menus in the box.  Since the whole idea of a lockable, comprehensive system DSP presumes a competent and experienced technician with the ability to fully utilize modern programs such as SMAART, easy and repeated access to the unit is not really a priority.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on May 16, 2014, 08:09:13 PM
I think I have pretty much everyone in agreement, or at least not in disagreement, that the $400 investment in a professional setup is the way to go. The guy I have been working with considers the Dx38 to be sufficient for a quality setup. It has 5-band PEQs on the two inputs and 4-band PEQs on each of the four outputs.

I was at the church last night and checked the current EQ settings. Only two bands on one input were set and everything else other than delays was either bypassed or an obvious default setting. I think the two filters were 200 and 400 hz or 400 and 800 hz. The filter widths were identical as was the db adjustment. I think this knowledge eliminated the interest in tracking down the guy that assisted with the setup originally using some measurement equipment. I am positive that we can do better.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on May 16, 2014, 08:14:08 PM
I am positive that the church board would approve anything that I ask for up to their $1,500 limit and the church body would likely approve more than that which is why I am very careful in making recommendations that spend church money.  What I want is what I get. I recently donated an amplifier because the AV determined that it wasn't a need, but I still thought it was necessary. In the end they were right, but I still like having more amplifiers than we need so we have options in the event of a failure. In the end, the group decision was better than mine.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Arnold B. Krueger on May 17, 2014, 08:14:14 AM

After looking at the DX38 it does not seem to lack the sum and substance of the electronic tools that I used to do what I did. What it does seem to lack is an easy user-oriented interface.

The RACE software allows you to use a computer to easily adjust and set up all parameters without scrolling/paging through the menus in the box.  Since the whole idea of a lockable, comprehensive system DSP presumes a competent and experienced technician with the ability to fully utilize modern programs such as SMAART, easy and repeated access to the unit is not really a priority.

Agreed, and I'm fully in agreement with that sort of thing as an important part of a good overall solution.

Various venues and even various configuration and usage modalities within a given venue have differing susceptibility to feedback. So, there is no one size fits all solution. Thus, trying to give detailed advice from thousands of miles away is fraught with difficulty.

When someone reports difficulty with feedback on a forum like this, it is hard to tell whether their problems come from having a tough nut to crack or comes from them stumbling into a situation that most experienced hands would immediately sense to be problematical and from experience and knowledge have a prioritized list of potential solutions at their finger tips.

In every case a well-informed, well-equipped  and experienced board operator is a big part of the best solution. Therefore anybody who finds themselves in this situation needs to consider where they are in that long unending journey to adequate training and experience. IOW, its probably not a situation with just hardware solutions.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Tim Padrick on May 19, 2014, 12:52:11 AM
I used to have them.  Too slow when ringing out, of no use at all when music is playing.  A good parametric, and an FFT app on your smart phone will do a better job.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on May 19, 2014, 02:37:21 PM
I used to have them.  Too slow when ringing out, of no use at all when music is playing.  A good parametric, and an FFT app on your smart phone will do a better job.

Used to have what?  I'm not sure which previous post you are referring to.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Tim Padrick on May 25, 2014, 11:23:25 AM
Used to have what?  I'm not sure which previous post you are referring to.

I had feedback eliminators - the subject of the thread.
Title: Re: Any recommendations for an affordable feedback eliminator?
Post by: Jon McElvain on November 21, 2014, 10:42:30 PM
As a follow up to this thread, we didn't end up getting professional help or any new components. I made a few adjustments in the processor and learning a few things to try on this forum and talking to the guy I was talking to about doing a setup for us. We didn't actively decide to not have a pro setup done, but all of the things that were objectionable to our ears has stopped. I don't know if the adjustments made the difference or not as the issues seemed to come up without any changes so they may have resolved themselves. We also ran a campaign to get people to hold the microphones and things have improved in that area a bit as well.

For now, things are going well...