less feedback when band is playing

Discussion in 'Location Recording' started by kmetal, Apr 20, 2013.

  1. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    I've notice numerous times in various bar/club type places that the acceptable vocal level when the band is playing, feedsback when the stop. i just ride the fader, or hopefully find an optimal balnce, and gate setting. or turn the monitors down a bit My guess is that all the stage noise is creating some kind of nulling effect and causing cancellation. and then when they stop i'm just amplifying the air and magnetic field.

    But i don't really have a solid explanation, if any does, it'd be great. or there could easily be an error in my technique. thanks!
     
  2. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    Are you compressing the vocals?
     
  3. Audiofreek

    Audiofreek Active Member

    Pretty much,but not sure what you mean by magnetic field.
    I think the room ,and surface resonances get excited by different frequencies as well,and that comes into play.When there are fewer interfering waves causing cancellation,the dominant frequency wave can propogate creating a feedback cycle that is free to build.
     
  4. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    boulder, usually barely, and not to start. by barely i mean a couple db @ like a 2.5 ratio, and a medium fast attack/release. Live compression is one of my wonders, so i keep it easy, or none at all for now until i figure out what much better/experienced live engineers do, to tame vocal dynamics.

    audiofreek, i just meant the magnets between the mics/mons/mains being powered as creating some sort of magnetic field. where maybe the power amps were interacting w/ all of them to create some sort of physical movement. i dunno if thats even really why. but like how you can just turn a vacant mic up enough to squeak. not sure what causes that, gonna have start researching my 101's i guess.

    So, your saying that basically it's that the 'lone' cranked vocal is interacting badly w/ the room.? is there another way to remedy that besides just push the fader down, that you know of?it makes sense based an my basic level of acoustics knowledge.

    i'm gonna have a lot of questions about live stuff coming up, even tho i've been at it for a few years, i've just got a very demanding person that wants his band to sound like it's concert, even in small bars... while his fantasy may/may not come true, it's a chance to improve my skills. even a couple of national acts i worked for didn't complain to me, so i expect a certain level of um, pretentiousness, on his part, but either way, i can get better/more refined.

    any insight is worth it's weight in gold to me, and i appreciate all your time.

    thanks. kyle.
     
  5. Kurt Foster

    Kurt Foster Distinguished Member

    do you know how to "ring" the monitors out?
     
  6. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    not really man. in a caveman way i used to (get mix levels, mess w/ graphic eq for a couple).

    all the stuff i've been reading about the past couple weeks on feedback, mentions 'ringing out' the room. even the manual for my dbx 166xl, which i use for my bass rig.

    I don't know how to execute the process the right way. for mains, or mons.

    especially in front of a place that already has patrons there already. i did modestly try it last night after 5min soundcheck, cuz their presonus boars has rta and feedback indication.

    i spent hours reading 'feedback suppressor' units manuals thurs night, and opinions on them. seems like a fixed installation thing to me, and since i already like the driverack, no practical use for me if i'm gonna invest modestly in that technology.

    From what i gathered i need to know how to ring out something besides a t-shirt, manually, or semi-manually. my concern is that patrons are there. is there a modest way that won't kill the 8'0 clock bar crowd. or do i need to step up and tell the band to get there the night before, or, have the bar open early for us.

    How do you ring the monitors out? and at what point in the soundcheck? in front of people, and not in front of people?

    thanks.

    p.s 'ring out a..." became new to me only a couple days ago. i have a lot to learn.
     
  7. Kurt Foster

    Kurt Foster Distinguished Member

    to ring monitors out you set up all the mics and speakers floor monitors , side sweeps ... then you start with the monitor system ...depending on how many programs of monitors you are using, start with one and set the eqs flat and open up all the mics on that program at the approximate levels they will be at. then slowly bring up the main volume. at some point he system will start to feed back or "ring". locate the point of feed back and attenuate it with your graphic eq (1/3rd octave eqs are best for monitors). repeat this process twice more .. repeat the procedure for any other programs of monitors you may have .. now your monitors are rung out .. shouldn't take more than a few minutes to do but yes it will annoy other people in the room so if you can gain access early it helps.

    now repeat the same procedure for the mains with the monitors turned off. this will also annoy other people in the room. 10 or 15 band eqs are usually best for mains imo.

    last bring down all levels and power up mains and monitors together and bring the levels up slowly .. search out any last freqs. that are still resonating and attenuate them. that's a s loud as it's going to get.

    imo, compression should only be used on the main 2-bus mono bus to protect speakers. adding compression on the channels only creates situations for feedback to occur.
     
  8. DonnyThompson

    DonnyThompson Distinguished Member

    Yup. Sound checking in a room filled with customers sucks. The band you are working with wants it to sound like a concert? Then they should be willing to get there and be there early enough for a proper sound check at an appropriate time for you to ring out FOH and Monitors without killing a dinner crowd.

    Then again, there are times when the club won't let you set up and check until a certain time that they dictate, so you are kind of at the mercy of the club owner, too.

    In very rare cases do you see a pro act's sound company still adjusting noticeable levels after the audience has arrived. Yeah, there's a bit of tweaking here and there, or the occasional problem that the crew will be fixing, but by and large, if you go see a "pro" act concert, the FOH and the monitors were taken care of hours before the audience arrived.

    And It's a two way street...while you can ring out the PA to a large degree before the band gets there, you can't do everything. Proper sound checks generally deliver good sounding shows... so, if they want it to sound "pro", then they have to do their part, too.
     
  9. Audiofreek

    Audiofreek Active Member

    Running the front end in reverse phase with monitors helps alot to reduce howling feedback.
     
  10. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    Good. Keep compression to a minimum until you have more experience. It can increase the likelihood of feedback. When the person is singing (or there's enough bleed) the compressor is reducing the gain. When they stop the gain will come back up and possibly make the mic feed back. One trick is to use an XLR splitter and put the mic into two channels, one with compression for the main speakers and one without for the monitors. That also gives you different eq for monitors (if your board has post-eq pre-fader aux sends).
     
  11. Kurt Foster

    Kurt Foster Distinguished Member

    i agree. mons should be pre eq and pre fader even if you are sending the monitors from the FOH board. but you will be limited by the number of pre aux sends you have on the console for monitor programs and this may impact the amount of aux send available for efx.

    most boards send aux signals pre insert so compression can be used on FOH without a separate split but imo i would not compress vocals ... maybe bass or guitars. in most large venues i have worked the sound guys only compress the mains. live is different than recording.

    another thing is most expierenced monitor and FOH engineers have developed relative pitch so when they hear ringing they can readily identify what frequency it is ... i know a 5K ring when i hear it.
     
  12. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    I actually like post eq monitor sends. I deal with feedback by making the monitors as flat as possible (except for perhaps a HPF) and then cutting at most a few narrow frequencies. Flat response sounds louder and clearer right off the bat which tends to head off requests for more monitor volume. Above a certain threshold of stage volume the situation collapses into damage control, cutting more aggressively as you increase the volume. But at sensible stage volume I use the eq primarily to get flat response from the monitors rather than ring out.

    Pretty much all the analog consoles I've used have the insert ahead of all the aux sends, usually:

    preamp -> HPF -> insert -> pre fader aux sends -> eq -> fader -> post fader aux sends -> pan -> main/sub bus assign.

    Sometimes the insert is before the HPF, sometimes the pre fader aux sends are after the eq.
     
  13. Kurt Foster

    Kurt Foster Distinguished Member

    this is fine and dandy if you are using separate mixers for FOH and Monitors. If you are mixing mons from FOH if you use a post eq aux send then every time you make a change in the eq or ride the fader (for the mains) the monitors change too. Nothing upsets a band more than monitors that are constantly changing.

    i agree with this. if you ring the monitors as i said, that will be as flat as possible. each time feedback is encountered you should cut a dB or two no more ... so if you do this three times, you should come up with cuts of no more than 2 or 3 dB at three different frequencies.

    which mixers would that be? i have not encountered that. pre means pre .. at least eq and usually pre insert. my computer is slow but i'm going to d load some pdfs of different mixers block diagrams. i'm pretty sure most will show the pre aux's are pre insert as well as pre eq. i have seen higher end consoles that feature both pre and post inserts. i'll give you that.
     
  14. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    I don't change eq much after sound check (which may include the first couple of songs at a smaller show with limited setup time) and anyway the changes tend to be improvements on stage as much as out front.

    I used a reference mic and a digital parametric eq to get my monitors' response as flat as possible. I have a preset that leaves a few filters free to deal with variables like acoustic environments and performers' habits. I haven't used a graphic on my monitors for the last couple of years.

    Pre just means pre fader. They are post insert on:

    Mackie 1604VLZ Pro (pre eq)
    A&H Mix Wizard WZ3 16:2 (post eq, jumper selectable)
    Soundcraft GB2R (post eq, jumper selectable)
    Midas Verona (1-6 switched per channel pre/post eq, 7&8 post eq but jumper selectable to follow the pre/post eq switch)
    Yamaha MG 206C (eq -> insert -> pre fader aux sends)
     
  15. DonnyThompson

    DonnyThompson Distinguished Member

    As a side question... just curious...

    are you dealing with guys who are pros when it comes to stage volume or are you dealing with rock stars who are constantly turning up and battling each other?
     
  16. Kurt Foster

    Kurt Foster Distinguished Member

    bouldersound;

    you are correct and i was wrong ... most pre send aux's are post insert ... live and learn. i have never run into this as an issue because as i noted, i don't use compression or separate effects on individual channels. only on sub and 2 mix bus's ...

    as far as having a global overall preset for the monitors, i don't see this as really viable. i have noticed drastic differences from venue to venue in my experience. now if i were working the same venue with the same band / stage set up every time, then a preset with minor tweaking would work but the minute you have a different band with a different stage plot the whole game is changed.

    if what works for you works, i say fine but i don't think what you discribe would work for me. i am much more comfortable relying on my ears than a reference mic and having monitors (that i can't hear from FOH) that change with every tweak i make on the mains, would be a no go for me.
     
  17. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    Yeah, what I'm doing is a fundamentally different approach from the old ringing out procedure. Getting the monitors really flat is the key. A 1/3 octave eq is too blunt an instrument to do that, with wide filters and fixed centers. Cutting with a 1/3 octave eq takes out relatively large chunks of the spectrum, which decreases intelligibility, which drives up monitor levels, which adds to stage volume which makes you have to cut more, which decreases intelligibility... Sure, sometimes I have to revert to combat audio mode and hack the eq to get through stupid loud stage volume, but I don't make that my default starting point.

    I do use compression and it does go to monitors, but I keep the thresholds high on vocals so it's just knocking down momentary peaks and not affecting the signal most of the time. I've seen people mixing live where the vocal was in gain reduction the whole time. That's the kind of situation that can exacerbate feedback, hence my original question to the OP about compression.
     
  18. dvdhawk

    dvdhawk Well-Known Member

    A couple quick notes:

    1) Outboard feedback suppressors suck. Their only valid application is as a last line of defense in an install where they are absolutely clueless beyond the On/Off switch. Suppressors will destroy the sound once they start taking out notches.

    2) You've got all the tools you need in the Presonus mixer, which apparently you're using with a computer for the RTA - perfect! More than enough right there. The RTA makes this really easy, and eliminates the need for a trained ear for identifying the freqs. (not that you shouldn't be making mental notes correlating tones to EQ bands)

    3) If, like bouldersound, you would prefer the Aux sends to be post-EQ on the Presonus you have to change a setting in your StudioLive's System Menu.

    a) The default setting is "Pre 1" which sends signals to the Aux mix AFTER the Gain, Phase, High-pass, and Gate (but BEFORE compressor, EQ, limiter, and fader).

    b) If you change your System Menu to the "Pre 2" setting, your Aux mix reflects ALL of the Channel / Fat-Channel settings, (Gain, Phase, High-Pass, Gate, Compressor, Limiter, and EQ) everything except the fader.

    c) Whether you're set to Pre 1 or Pre 2, the Post button does exactly what you'd expect, post everything including fader (which as Kurt says, the band will HATE if it's controlling their monitors).

    4) If you're using the SL24.4.2, dialing in the Expander would be all you need to keep from riding the fader between songs. If you're using the 16.4.2 you still have an Expander, but it loses the, very useful in this case, "Range" control. If it's a 16.0.2, no Expander for you.

    5) Whether or not you annoy the bar patrons ringing out the monitors will depend on your fine-motor-skills. Regulars at a live music bar won't even notice you doing it, as long as it's not loud sustained ringing. If you have the gentle touch to v e e r y . . . . s l o o o o w l y increase the Aux send master until it just barely starts to regenerate for a half second that's all you need. It doesn't have to ring loudly for the RTA to show you that most sensitive frequency. If you go slowly, it will only ring the one worst / most over-sensitive freq. rather than a shrill painful combination of two or three at the same time. And as Kurt described, repeat the process until you knock off the worst 2, 3, or 4 offending frequencies and you're usually in pretty good shape. Notice how much farther you can turn the Aux up with each freq. you tame down. Make sure nobody repositions any monitors after that, or you may have to do it again.

    6) The best way to sound like a big-time band in a small-time room is to have a band who knows how to rock at minimal stage-volume and let the PA fill the room (assuming you've got a PA that's up to the task). It takes a good soundman, with a good PA, and a band willing to put their personal preferences aside for the good of the team - as long as it doesn't completely suck the energy out of the performance. To get a band to turn that much control over to the soundman, you will definitely have to earn their trust. I've been on every side of this problem, but I'm a musician first. I completely understand that there's a level below which the band gets uncomfortable and un-energized. Then on the other end of the spectrum, the louder they get on stage, the harder it is for everyone to hear - even them. If I had to choose between a tiny bit of feedback and an uninspired, lifeless performance - I'd take riding the slider, and occasional feedback every time.

    7) If you're having ongoing problems with feedback from the Mains, you need to rethink speaker position, mic selection, and whether future gigs at Larry's Chicken Shack are really advancing your band's career. Don't think club owners don't know which bands can't get their feedback under control.

    8) If the singer holds his mic watch him closely, and make sure he's not relaxing between songs in a way that would let his arm fall to a natural resting position that points his mic directly at the monitors. Also, if you have a singer with a wireless mic who thinks it's cool to wander around the dance floor and in front of the stacks, without any regard to which way his/her mic is pointing - a pool cue to the knee caps ought to fix that.


    Rock on! Good luck!
     
  19. moonbaby

    moonbaby Mmmmmm Well-Known Member

    I have a "dumb question"....are you SURE that the feedback is only when the band stops?
     
  20. Davedog

    Davedog Distinguished Member

    Sometimes the stage-wash is so much it masks this feedback, so every song has this standing frequency adding to the overall volume. Its more noticeable if its not in the same pitch as the song....
     

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