Change order of Eq and Compress

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This topic contains 105 replies, has 7 voices, and was last updated by Profile photo of Mfk0815 Mfk0815 5 months, 3 weeks ago.

Viewing 15 posts - 76 through 90 (of 106 total)
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  • #93123
    Profile photo of volounteer
    volounteer
    Participant

    @mfk0815

    If you looked at the diagrams with the links I posted andor read the description you would know that the compressors are set
    so that low signals are increased and high signals are made lower and that it is normally done by heavily compressing the signal and then adding in the right amount of the un (or very lightly) compressed original signal often done in parallel with two channels then summed.

    The net affect is that the highs of the signal get pushed down while the lows get raised up. And the net is in the middle of where it was originally. The DR is reduced. There is no risk of feedback.

    There is always noise and other practical considerations but that limits how much you can do not mean you cannot do it at all as some seem to think.

    #93124
    Profile photo of Mfk0815
    Mfk0815
    Participant

    You can repeat your stuff as often as you want, it will not become true that raising the gain in one or the other way do not increase the risk of feedback in live situation. Period, exclamation mark.
    A standard (downward) compressor cannot cause feedback by itself, because it lowers only a signal. But if you combine it with a second processing step (call it makeup gain) the risk of feedback increases.
    Of course you can use all these processing options, but you have to be aware of the potential risks. But if you say „no this upward compression stuff will never increase the risk of feedback“ you are completely wrong. You have to learn that truth the one or the other way. Afaik the QU32 is equipped with sub groups, so you can do some experiments with parallel compression in live situation. Do it an learn your lessons.
    Period.

    #93125
    Profile photo of volounteer
    volounteer
    Participant

    @markpaman

    If I can train a DJ not to send a distorted “all the red lights” signal to my PA, and to trust me to make it loud, then anything’s possible!

    I suspect you had access to the person and they actually listened to you and tried to change.

    We do not have the luxury of talking to the orator nor would they listen to us if we could.

    #93127
    Profile photo of MarkPAman
    MarkPAman
    Participant

    @Volounteer – This thread’s got very long, and some of the info’s in other threads, so forgive me if I’ve missed or forgotten something.

    You said:

    Tell me how this is wrong:

    We tune the room EQ the mikes and do all that good stuff you like
    then we raise the mike gain in the preamp until it just sings gently.
    Then we back it off as many dB as you like for a safety margin.

    Now we back it off another ten dB.

    So our mike gain is set at a point where the speaker can speak until the mike puts out 10dB over the existing noise level with no compression of any kind.
    And we still have our safety margin.

    The speaker can speak from anywhere at nothing to a loudness causing 10dB signal.
    If the speaker is whispering and causing 1dB of signal then could raise the gain in the preamp 9dB and still no feedback as we are under our safety margin. But that would be risky because as soon as he talks louder the system howls.

    That’s not normal – it is wrong, but why?.

    Putting aside compressors of any sort for now as none would cause this.

    There’s something not right here, a louder input from your speaker does not, by itself, increase the system gain, as the speaker is not part of the loop. You should not be getting feedback in this situation. But evidently, something must be increasing the gain if you get feedback.

    So, I wonder what is causing this?

    I think you’ve said that mic is in one place and not being moved or cupped?

    I’ve a couple of guesses, but that’s all they are!

    1)
    I think you’ve mentioned somewhere in the past that you think the AMM is used for some mics on the desk? Is this mic one of those?
    If, as your speaker gets louder, the AMM is turning down other mics while turning up this one (keeping their combined gain the same), that could be causing this. Especially if the other mics are further away or back from the PA, so less likely to contribute to feedback. So check the AMM settings, (if you can access them?) and if this mic is in the AMM, take it out.

    2)
    I’ve had something like this happen when the room’s installed induction loop system has somehow been picked up by something and fed back into the desk*. May well have been the desk itself (which was old & analogue). I don’t know why it only became a problem at higher volumes, maybe the loop had some sort of gate it?
    This is easily tested by turning off the loop, though that’s rarely an acceptable long term solution, you will at least know why you have this problem.

    * Some guitars seem to be particularly good at picking up induction loops, though any unbalanced part of the system can contribute.

    There could well be another cause, but it’s difficult to know what else to look at without more info.

    #93128
    Profile photo of MarkPAman
    MarkPAman
    Participant

    I suspect you had access to the person and they actually listened to you and tried to change.

    We do not have the luxury of talking to the orator nor would they listen to us if we could.

    Yes, of course I was able to speak to them, and I’ll admit that it took time – several events. Take time to get to know them, be their friend. We both want the same thing – the best sound possible for the audience.

    Show them that you’re not there to be awkward or spoil their fun, but that in fact it will sound better if if the equipment is used as it was designed to be.

    You speakers will want their message to be clearly heard, soo show them that that’s what you want too.

    When I do PA for large meetings with inexperienced speakers, I tell them to talk to the first few rows as if there’s no mic there, and I’ll take care of getting them heard at the back. Most people can gauge how loud the need to be, and an appropriate DR when there’s no PA, and if they can ignore the PA and aim for that level at the front, the PA job becomes much easier.

    #93129
    Profile photo of volounteer
    volounteer
    Participant

    @markpaman

    We do not get to talk to guest speakers let alone have multiple events to ‘train’ them.
    Clearly they think that they are excellent doing what they do.
    Else they would have learned by now and somebody with access to them would have told them.
    So why do they do what they do if they do not think it is somehow good?
    Does anybody try to do things poorly on purpose?

    Most speakers try to do their best. But most are not true professionals.
    Some think they are. Some think they are greater than sliced bread and have egos to match.
    And some are just old and set in their ways.

    And then there are the ‘pros’ who refuse to use a mike at all.
    Those are usually loud enough and rarely the problem.

    The worst problem I recall was a guy who was an ’emoter’
    He thought bending over whispering then bolting upright and yelling was somehow going to help us understand what he said.
    That guy was all over the stage, at times like a gymnast of sorts with his movements.
    I could not understand half the words as they were way too soft.
    And the prancing around was a distraction.
    I have no idea what he talked about.
    I almost think he was a charity case our pastor gave a chance to talk because he felt sorry for him.

    #93130
    Profile photo of SteffenR
    SteffenR
    Participant

    OK I watched some videos on upward compression, none of them with live sound in mind
    and the implementations of the upward compression plugins use all the mentioned method to avoid the raise of noise and extremly low sounds
    low and ambient sound gets mostly raised very strong and this is the use most of the videos trigger
    to get the room and ambience up

    #93132
    Profile photo of volounteer
    volounteer
    Participant

    @SteffenR

    One size fits nobody.

    Perfection is not possible.

    When you have a problem you should look at all feasible solutions then weigh them against non functional qualities.

    When other solutions fail you use what is left even if it was not created for that problem.

    #93535
    Profile photo of volounteer
    volounteer
    Participant

    @ALL

    wow

    who know one simple suggestion for improvement in the Qu would generate such a long discussion

    Thanks to all who elaborated on the issues involved.

    #93636
    Profile photo of volounteer
    volounteer
    Participant

    @mfk0815

    BTW. My Experience over decades is that doing automatic level changes in a live system, especially when the situation is not well prepared before (good microphone practice, low background noise, perfect tuned sound system and so on) is very risky. Especially if you allow the automatic to raise the volumn will almost always cause feedback. Ok, I do not have articles or academic studies to prove that, only my experience.

    Yet they have automatic feedback killers which work just fine.
    Combine the automatic DR squashing and EQ following, with the automatic feedback killer and still no problems.

    Should be no need for automatic feedback killing but always nice to have just in case:)

    #93642
    Profile photo of MarkPAman
    MarkPAman
    Participant

    “Yet they have automatic feedback killers which work just fine.“

    Do they?

    I’ve never met one that’s anywhere close to good enough to use ‘live’. They all are too slow and require the feedback to be uncomfortably loud before they do anything useful.

    And that’s before you get on to how it deals with intentional feedback, or long notes that sound like feedback.

    Imagine if Hendrix had had one 🤣

    #93646
    Profile photo of volounteer
    volounteer
    Participant

    @markpaman

    Perhaps a church audience is not as demanding as what you usually work with in the way of performance and audiences.

    #93651
    Profile photo of Mike C
    Mike C
    Participant

    I’ve never met one that’s anywhere close to good enough to use ‘live’. They all are too slow and require the feedback to be uncomfortably loud before they do anything useful.

    And that’s before you get on to how it deals with intentional feedback, or long notes that sound like feedback.

    Imagine if Hendrix had had one 🤣

    EXACTLY!!!!!!!!

    Just last night I actually had a show, 8 piece band, three horns.
    I’m sure the trumpet solos would have triggered any “feedback killer”.
    Not a hint of feedback during the sound check or the show and no FBK in use.

    If your going to or think you need to use an FBK at all, put it inline, activate maybe
    4 or 5 filters at the most, push up the system gain till it rings/feeds back, let it grab that one keep pushing till it grabs a couple more, bring the system gain back down
    to the normal level and then lock all the filters so it will not keep hunting and notching.
    That’s my normal tutorial to people who either have no other EQ on a system than an FBK
    or can never figure out how to do it by ear with an EQ.

    #93653
    Profile photo of Mfk0815
    Mfk0815
    Participant

    @mikec
    +1 from my side. I never wanted to use such tools. In fact it is not that complicated to find the most critical frequencies manually. The only advantag of such tools are the narrow notch filters that are used. Ifi want any feature in any actual digital desks is a replacement of that graphical EQs with a multiband Notch filter, lets say 6-8 filters with a Q-Factor between 20 and 60. classical graphic EQs are like axes used for brain surgery.
    Especially in a fixed environment of a venue it should be possible to set up the system once, so automatic feedback killer should not be required at all.

    But maybe we should come back to topic.

    #93657
    Profile photo of MarkPAman
    MarkPAman
    Participant

    “If I want any feature in any actual digital desks is a replacement of that graphical EQs with a multiband Notch filter, lets say 6-8 filters with a Q-Factor between 20 and 60. classical graphic EQs are like axes used for brain surgery.“

    This! I wonder if it could be added to SQ and above…….

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