Feature request: Feedback destroyer

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This topic contains 26 replies, has 17 voices, and was last updated by Profile photo of Lee7 Lee7 2 weeks ago.

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  • #60393
    Profile photo of drc_online

    Hi there, just getting to grips with a Qu16 and really wish it had an auto-feedback destroyer of the kind that uses super-high-Q EQ filters to notch out troublesome frequencies.
    I know you can use the GEQ on the mix outputs to do some degree of feedback suppression but that’s a bit of a sledgehammer to crack a nut as you’re dropping a whole 1/3rd octave rather than notching out just the problematic frequency.

    Ideally it would be an insert on each channel and contribute to the PEQ, but I’d also settle for it as a FX module that could be inserted into a specific channel.

    In general it’s only really one or two channels that need it on law mics or similar.
    I con do overall room stuff on the speaker processor, but just need a ‘tool’ i can insert on problematic channels.


    Profile photo of D.J.

    +100000 for Me!! I don’t understand how QSC (a speaker company!) can integrate Feedback Suppression in their digital mixer and A&H can’t. It would eliminate 3 items in my rack if feedback suppression could be added for the mix outputs at a very minimum. I understand how A&H couldn’t partner with DBX to put their AFS into one of these mixers (competition, you know); but companies like Sabine have superior feedback suppression technology that I would love to see added if A&H could partner with them and strike a deal to add that functionality into their digital mixers.

    Profile photo of GCumbee

    While there are extreme cases and lacking in good designs, training and gear I feel a lot of feedback problems can be handled. I don’t put any in my systems. I don’t even use the suppression built into processors. I try to design with speakers, positions, mics and good training to alleviate the need. Again I know there are specific situations. I’ve had mine too but I make logistical adjustments to try to cure or reduce it.

    When I see a church or facility where someone thought putting the speakers behind the mics then added a feedback suppressor I have to shake my head.

    Profile photo of [XAP]Bob

    Some church buildings are very limiting (listed status etc) but I have to agree – if feedback is a problem it’s a system design problem, and eq isn’t really a solution….

    Sure if you’re doing a one night setup then you might have to grab the graphic or the peq to help, but in an install you should be dealing with the issue.

    If it could be added as an FX option (though it would need a side chain input from the relevant mix?)

    Profile photo of Dick Rees
    Dick Rees


    You have PEQ on Mix outputs, so no reason to use 1/3 octave fixed filters. Additionally, you are not “suppressing feedback” with either FBX units or EQ. You are addressing frequency anomalies either in auto mode (FBX) or manually (PEQ/GEQ).

    The proper way to address such problems has been mentioned:

    Proper setup, positioning and DSP processing of both mains and monitors.

    If you’re wedded to the idea of addressing the problems after the fact instead of learning why they’re occuring in the first place, you can always use the FBX unit of your choice in line between the desk and the speaker system. But you can do the same thing manually with some instruction and a bit of practice utilizing the tools already in the Qu. And if it requires more than four filters plus the HPF, something in your system is grossly mis-positioned or mis-adjusted.

    Use knowledge, not gimmicks.

    Profile photo of debzdoodle

    Removing any ‘gimmicks’ I may have used in the past from my set-up has forced me to become a better sound person. I now utilize speaker placement, DSP, PEQ, GEQ and dynamics better than I ever did.

    Profile photo of neonjohn

    That all great, and I am a 35 year pro engineer. I agree with the OP. If QSC can put one in the Touchmix, and A&H can put a “D” mixer in the Qu series, there’s no reason a feedback suppressor shouldn’t be in there. It’s great to say, “well, a real engineer with a well-designed system doesn’t need it.” Real world: many of the users of these mixers are musicians and small bands, without well-designed systems, and in rooms that don’t allow proper speaker placement etc. Myself, I can ring out a room with anyone, but when I have a big corporate project with 10 lavs in a far less than perfect environment (and not enough time to set up), my DBX AFS-2 is an invaluable time and aggravation saver.

    So I’m 100% with the original poster. Please DO incorporate a feedback suppressor!

    Profile photo of Dick Rees
    Dick Rees

    Dear John…

    “Feedback suppression” programs may seem useful, but if you actually learn how to properly deploy and tune your system it’ll sound better and alleviate the need for such sonic crutches which degrade the sound at the expense of convenience.

    My sincere is that if you really want such a feature, purchase the speaker management unit and of your choice and do the auto-zapping there. You’ll get the additional benefits of speaker protective limiting, alignment delay and more.

    Profile photo of Scott

    Adding the other EQ models found on the GLD and dLive would be very helpful. The proportional-Q variant is much better for going after feedback than some of the others.

    DBX’s AFS-2 is a nice unit, since it takes much tighter notches out of the spectrum on its cuts than a standard graphic or parametric EQ. It can be used in manual mode as well acting like a very fine surgical graphic EQ.

    Profile photo of Dick Rees
    Dick Rees

    One significant problem with incorporating FBX in mixers is that the function is placed on the outputs and is not available on a per channel or per bus basis. Thus, a single problematic input will trigger removal of program material from the entire mix.

    You have now let your system be controlled by the weakest link in the signal chain rather than addressing the problem at the source. But if you REALLY need this function, it can be added as I described earlier. I prefer to ask for improvements/upgrades which can ONLY be added in the software and are not amenable to simply adding the appropriate outboard.

    Profile photo of Mike C
    Mike C

    Feedback destroyer type units on software are just a crutch to help you limp along at best. Keep in mind they do not stop feedback from happening, the system actually needs to
    feedback before they do what they attempt to do.

    IF…. you really feel you need to use some form of an FBX unit let it ring out a few frequencies and then lock the filters so it does just does not keep cutting away at everything it hears and thinks is feedback because pretty soon you’ll have nothing left coming out of it.

    Actually FBX units are good for service call work!!!!

    Profile photo of Mike C
    Mike C

    I meant to say……Feedback destroyer type units or software….. not on software.

    Profile photo of Dick Rees
    Dick Rees


    I have always maintained that once you understand how to use an FBX unit as a PEQ, you can simply use any PEQ such as those already available in digital consoles these days to do the same job as well as or better than auto-EQ/FBX programs…without the downside such units bring with them.

    Profile photo of Mike C
    Mike C

    I have always maintained that once you understand how to use an FBX unit as a PEQ, you can simply use any PEQ such as those already available in digital consoles these days to do the same job as well as or better than auto-EQ/FBX programs…without the downside such units bring with them.

    And that’s the Gist of what I was getting to in the very last sentence of my post.

    Profile photo of Hercules123

    I use the delay feature on my Qu outputs & delay my monitors approximately 10-15ms and eliminate feedback problems all the time. Depending on the environment & stage & stage environment, you can accomplish the same thing without feedback programs or units. I make sure there’s no actual delay of any kind to be heard or felt & it works great for me. I’ve also have delayed the outputs as much as 18ms without any problems or delays of the signal only in the right environment. We are all mixing to & balancing our mixes to our acoustic environments.
    At a church I had the audio Engineers use that feature with an Omni directional lavaler mic and when the minister realized there wasn’t anymore feedback he was like a little kid.
    This idea of depending on feedback suppressors is a bad idea & doesn’t teach anyone anything. I do understand on certain situations it does and or would come in handy. I use the gorack at one gig in the winter for children’s choirs because they sing so soft with a pair of Shure sm81’s and it works well, otherwise the other 50-100 bands I mix I don’t use any feedback suppression. And many times I only get 20min-30min between bands.
    With the Allen & Heath you get parametric eq with your 1/3 octave on every output. If you can’t get great mixes in challenging environments with the delays on top of that, I don’t have an answer for any engineers not training your ears. Those are your most important feedback answers.

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