Quick! Learn me about compression for vocals.

Discussion in 'Live Sound [BG]' started by blastoff99, Feb 14, 2014.

  1. blastoff99


    Dec 17, 2011
    I apologize in advance for my criminal ignorance....

    Ok, so I do FOH at my church. I mix very well, but am admittedly deficient at most things related to that rack of processors behind a tinted glass door. I guess I get intimidated by all those knobs with tiny writing around them and mesmerized by the blinking lights. :)

    So last weekend (someone else doing FOH) we had a challenging vocalist leading, and the usual BL singing backup. For some inexplicable reason, they had the sub leader use the BL's mic (and channel), and put the usual BL on a different mic. I'd have perhaps done this differently. Anyway, *everything* changed.

    This weekend the BL is back on his usual channel. I fixed the gain, fixed the fx, fixed the EQ... and have a compression nightmare. They tweaked it heavily for the sub, and it absolutely doesn't work for the BL. In fact, it sounds like he's singing from underneath a sofa.

    I don't know what I'm doing here, so I thought fast and copied over the settings from the compressor on the channel where he was last weekend. Didn't work. Still under the sofa.

    Then I gained down some and hit the magic button called "bypass." This sounded much better than under the sofa, but leads to its own problems. By the time rehearsal was over, I had achieved, through random and ignorant knob turning, something sorta ok, but it was very prone to feedback.

    So my choices are:

    1) Under the sofa, but no chance of feedback
    2) Out from under the sofa and sounds sorta ok, but high feedback potential
    3) Bypass
    4) Get a brilliant suggestion from one of you.

    Yes, I could break out my big Yamaha book, but I'm too stupid to understand it and it makes my head hurt.

    Everything's analog. The compressor is some old dbx unit that has four knobs and three buttons and two sets of lights. I'd like to be more specific....

  2. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Compression is not for feedback control. You will get best results if you use the threshold control (and watch the rows of LEDs) to manage the peaks and valleys of VOLUME of his singing voice, and do not for even a second think about changing the settings to control feedback.

    Now use EQ to notch out the wolf note where feedback occurs.

    If you do that and still get feedback, then try re-positioning the mikes so they are not pointed at any speakers. If there's a panic situation during the middle of a live set, turn down the volume on his mic channel just a bit, just to stop the feedback, and deal with his complaining about the volume afterward.

    The "under a sofa" sound is from way too much compression--probably because of the whole feedback thing. Use much less compression and he should sound fine.
  3. blastoff99


    Dec 17, 2011
    Yes- I do get that compression is not for feedback control. I am just a bit curious that when I kinda sorta fixed the compression, I got feedback even though I'd restored his EQ to normal.

    Here's the problem with what you said: I'm not sure how to reduce the compression. Yes, there's a knob that has ratio on it, and I bet that 2:1 is less than 8:1 (which is where it was!), and I should reduce that. But there are three other knobs.

    I'll try to find a pic.
  4. ngh


    Feb 6, 2013
    brooklyn, ny
    the first thing to understand is what you are doing with compression. you are trying to reduce dynamic range by bringing the peaks down in volume i.e. make the loud stuff be closer to your quieter stuff so that you can turn your quieter stuff up without having your loud stuff hurt so much. assuming that dbx you are describing is a 160a or some such (which I think it is) you have 3 knobs. the first is labeled threshold, this tells the compressor at what dB it should kick in, so if you set it high that means it will not kick in until there is a really loud peak. so start with this knob all the way up. your second knob is your compression ratio, this sets the "amount" that your signal is attenuated once it passes the threshold. in other words at a very high ratio like say the 8:1 setting it was on, any signal that passes the threshold will be attenuated down to the threshold level and will lose all of it's dynamic range, sounding like you are under a couch. at a lower ratio like say 2:1 or 3:1 on the other hand, the signal will still be attenuated past the threshold but it will have more breathing room above that point. next is your make up gain, when you compress a signal it will get quitter according to your threshold, at this point you are simply adding back the volume so that it is loud as it was coming in.

    so in short start off with a lower ratio, and then start bringing down the threshold until you start to see a little action on the meters/ start hearing what you want to hear. then compensate with the makeup gain and you have compressed a thing with a thing!

    not the most eloquent explanation in the world but maybe it will help you out
  5. Sponsored by:

  6. aprod


    Mar 11, 2008
    "Learn me" really? Is English your second language?
  7. ngh


    Feb 6, 2013
    brooklyn, ny
    also, don't be afraid of your big yamaha book, flip to page 270, there are 4 pages on the basics of compressors, including a section called "14.3.3 setup adjustments" which should help you quite a bit. that big black book is your friend!
  8. blastoff99


    Dec 17, 2011
    Thanks, ngh. Very helpful info, and your response was easy to understand. And I'll crack open the book.

    aprod - No, English is not my second language. "Learn me" was an attempt at humor, and not an original one, but apparently it was lost on you. Sorry to upset your delicate sensibilities. :rolleyes:
  9. stonewall


    Jun 14, 2010
    If you dont know how to run it by-pass it until you do some reading..Learn your board fully before you start messing with affects.
  10. ngh


    Feb 6, 2013
    brooklyn, ny
    glad to help, there is a really good diagram in the compression section that explains ratio really well if you are a visual person.
  11. Geri O

    Geri O

    Sep 6, 2013
    Florence, MS
    Another problem that compression exacerbates is that you compress the vocals to a degree, then you bring up the output of the comp for make-up gain. What is happening is that when the comp is reducing the vocal gain, the feedback threshold is lowered. But when the singing stops and the actual uncompressed mic gain comes into play, you are closer to the feedback threshold. It "blows up" on you.

    As suggested earlier, I'd turn off the compressor altogether and work on feedback control through mic placement (including talent placement), EQ on the mic and the system, and maybe even the pattern type of the mic causing problems.

    It would help to know what kind of mic you are having trouble with. Handheld? Lapel mic? Headset mic? The pickup patterns?
  12. blastoff99


    Dec 17, 2011
    stonewall, that's still a possibility. If I can't iron this out quickly on Saturday, I'll take that option.

    Page 270 duly opened.

    Geri O, that makes a lot of sense. I felt like I was getting into that problem last night at rehearsal. The mic is a KSM9, in the same place and with the usual lead vocalist. They only time I have feedback problems with this configuration is in the key of Bb, and we're not doing that. I'm having to take a chunk out of the low-mids that I have not had to take out before with this vocalist with this mic in this location on the stage. Yes, I can solve that, but I found it odd that this is a problem I haven't had previously - and I have it now that I'm having compression follies.
  13. Biggbass


    Dec 14, 2011
    Planet Earth
    I've found the best use of compression for a live mix is to not use it at all.
  14. Geri O

    Geri O

    Sep 6, 2013
    Florence, MS
    Oh, dude! You have to have some hair on yer chest to deal with a KSM9 anywhere near monitors or the main PA. That's an awesome mic, no doubt, but it's VERY sensitive! I really think you'd fare better with a trust ol' SM58, or something that's not a condenser. But if you work with it and your situation improves, then more power to you! KSM9s are outstanding mics when used with IEMs, but they are a bear with speakers in near proximity. I'm particular with microphones and their patterns and characteristics, I have to be because I'm the guy around the state known for mixing orchestras and Gospel choirs (and since I started playing again, those genres are about all I care to mix).

    Comps certainly have their place, but I'd save it to keep a handle on a very dynamic singer, worship leader, or pastor. Just to keep the loudest peaks in check.

    Actually, I think you are in a good situation to work with what you have and learn some things. That's how all of us learned our craft, whatever it is.

    Good luck!
  15. walterw

    walterw Supportive Fender Gold Supporting Member

    Feb 20, 2009
    OK, my attempt at "vocal comps for dummies":

    set the ratio to 4:1

    set anything that says "auto" or "overeasy" or "contour" on.

    set the output gain to "0" to start out.

    here's the key to not using too much compression: adjust the threshold knob to where only a few lights kick on while the singing is happening.

    that row of lights is your friend! it tells you how hard the comp is turning down the sound, so if the vocals are too quiet and you see like 8 lights in a row lit up, you know to turn the threshold up to where only a few are on and get your volume back.

    the idea is to push down the very loudest bits a little without doing much to the quieter stuff.

    comps on vocals are for keeping them from getting too loud when somebody belts it while keeping them from disappearing when they sing quiet. more of a rock thing, i think, but i've always liked at least a little on vocals to smooth them out so you can keep them just above the mix where they belong.

    look at the model of comp it is then check the DBX webpage for the manual on that unit, it'll be quite helpful.
  16. blastoff99


    Dec 17, 2011
    walterw, you're speaking my language - well put for this dummy. Between what you said and what ngh said earlier, I think I've got it bracketed.

    Geri O, we do use IEMs. Back when we had wedges to go with our KSMs, it was a real mess. Generally we have three or four KSMs on stage... right under the mains. As long as the vocalists stay right on top of the mics we're ok, but 4" away is a bad thing.

    Thanks to you gentlemen, I've got a much better handle on this than I did this morning. :)
  17. Geri O

    Geri O

    Sep 6, 2013
    Florence, MS
    Glad to hear that, and in a bass forum, of all places...:D

    One other thing to be aware of if you have a center cluster of speakers, or a left/right set of speakers with more than one speaker on each side. If two or more speakers are placed side by side, you'll have a lobe from the coupling of the low-frequency drivers that extends downward (and upward, too, but that one isn't too much to worry about) in the area of 160hZ to 300-350hZ, depending on the crossover settings. This could have been the cause of the low-frequency feedback occasion you mentioned early on. Again, it's not a lot to lose sleep over, just remember that careful placement and some EQ-ing will get you through the experience (oh, and a singer(s) that actually uses air and a lot of it to sing with!...;)
  18. walterw

    walterw Supportive Fender Gold Supporting Member

    Feb 20, 2009
    oh yeah; IEMs or not, do what it takes to keep the compression out of the monitors!

    that means anything from grouping all the vox into a subgroup and just compressing that to splitting every vocal mic cable into two channels each, one compressed for out front and the other un-comp'ed for monitors only.

    also, if you've just got the whole system going through a compressor, i'd be inclined to skip it entirely! you get the thing where somebody sings loud, the compressor squashes down, and the whole band gets quieter behind the vocals then comes back up when the singing stops; that kind of stuff is the so-called "pumping" and "breathing", and sounds thoroughly weird.
  19. Geri O

    Geri O

    Sep 6, 2013
    Florence, MS
    Excellent point, Walter, I wish I had thought to bring this up...:crying:

    Compression in the monitors, especially heavy compression, can freak out the singer. They push and push and can't figure out why they aren't getting louder. Kinda the same reason I don't use compression on my bass through my own amp. Let the sound guy decide whether or not to compress and how much.

    I'll say that we use one digital console for house and monitors in our church and they tell me that they use way less compression on the bass input when I play.

    When I was 18 years old, I did a recording session in Memphis, TN and the engineer at the time suggested afterwards that I sit down with something that had a VU meter (for example, a cassette recorder set to record and pause) and see how motionless I could keep the meters as I played from note to note. Use dynamics, don't try to keep the meter on the same place on the scale, but try to keep the meter from jumping all over the place as I play. I worked on that for years and still do. I guess it was good for something...:bassist:
  20. blastoff99


    Dec 17, 2011
    walterw - no compression at the monitors console. I can see how that would be a great way to freak out the vocalists, though... hmm.... ;)

    Geri O - my feedback issue is a little higher up than that - I'd say (for lack of a frequency monitor) it's in the area of 500 - 600Hz. And it's not a problem I've ever had before with this vocalist. I expect I won't have it today. The reason I can say this with some confidence is that somehow, someway, between Thursday night's rehearsal and Saturday's services, things change. I don't know if gnomes break in and turn knobs or what, but that's what it seems like. Sometimes things change for the better, and sometimes they do not.

    And, just so we're clear on one important point: the problem here is NOT the vocalist. He stays right on the mic, and belts it out good. The deficiencies are with me, and only with me.

    As for finding this advice on a bass forum, I've come to the conclusion that on this forum there are people here who can answer anything and will do so clearly and politely. Just look at OT - right now I think we've got everything from head gaskets to taxes. :hyper:
  21. Geri O

    Geri O

    Sep 6, 2013
    Florence, MS
    Give yourself some credit, you see the issue and are working to resolve it. And bonus points for NOT bashing your artist....:D.

    You won't believe how many times in over 30 years, I've observed a problem like this crop up and the operator either didn't appear fazed or motivated to address the problem, or got that deer-in-the-headlights-look and froze in fear and panic.

Play guitar too? Become a founding member of TalkGuitar.com