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Speaker phasing live?

Discussion in 'Live Sound [BG]' started by bassmatt4792, Jul 21, 2012.


  1. Lots of people here dislike the combination of speaker sizes for bass stacks due to phasing issues. My question to you: how is phasing not apparent in a live setting then? My band has 2-2x15 cabs and 2-1x18 cabs for our PA. If my bass sound would phase if I had different size speakers, why is there no phasing if my head goes through my 410 and DI through our PA?
     
  2. It will if your stage volume is so loud that it competes with the PA.

    The different sized drivers in your PA are not running full range, and therefore not subject to phasing.

    Your stage volume should be enough to hear yourself, not to compete with the PA.
     
  3. Dantreige

    Dantreige

    Oct 22, 2009
    Wisconsin
    +1 There ARE issue with phasing (always!). You minimize them as much as you can by keeping your volume under control on stage. Often FOH is often time delayed to your backline so it is reinforcing, rather then competeing with stage sound waves / volume / noise.
     
  4. mwbassace

    mwbassace

    Jul 26, 2010
    N.W. Ohio
    From what I understand about this, your actually talking about 2 issues. FOH/backline phasing is one issue and can be fixed as said above. Different driver sizes is the other issue and they can work together with the use of a crossover.
     
  5. Steve

    Steve

    Aug 10, 2001
    whether phasing is from mixed cabs or stage FOH conflict,I can not ever remember working an indoor space where the natural phasing from the standing wave and reflected acoustics of the room weren't WAY,WAY worse.

    You could put a single source of mastered music anywhere in that room, then walk around the room and get completely different sonic profiles.

    IMHO YMMV
     
  6. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    It can be totally minimized if the PA is set up with some thought. Might not always go away because of room reflections, but what you're talking about with the different sound profiles as you walk the room is most often the result of putting subs on both sides of the stage and not having the required distance between them to stop it.
     
  7. Steve

    Steve

    Aug 10, 2001

    I'm talking about any indoor venue from a national act show to the local bar that the PA consists of a 15 /w horn on a stick.

    You stand in the corner and listen, the low end is huge, you walk in and out of the center axis of the horns and the sparkle comes and goes, you find the right spot as you walk the back side of the venue and the bass disappears for a few feet then reappears...

    I'm not saying there nothing to be done to mitigate the backline driven issues or the PA driven issues. I'm saying that the best thing you can do to get good sound inside is walk the room until you find the spot that sounds good to your ears and sit there.
     
  8. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Those are all comb filtering issues, and they can be nearly 100% eliminated by proper placement of the subs.
     
  9. 5StringFool

    5StringFool

    Jun 10, 2011
    Greenup, KY
    I'm a fan of placing the subs in the middle of the tops rather than one to each side. It may not look as cool but disperses the bass much more evenly.
     
  10. Steve

    Steve

    Aug 10, 2001

    I find those issues in rooms that don't even use subs.
     
  11. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Comb filtering can also exist in PA tops if they're not separated enough. It's just that subs are most often the culprit. There are also dispersion issues to contend with in a lot of instrument cabs, and if you don't run them through the PA or have cabs built to overcome them, those will also contribute. Again, nobody's saying that it'll be 100% perfect, but the vast majority of those problems can be reduced considerably with a little thought to placement.
     
  12. I agree with Steve, those issues exist in most venues, and I've seen 100s of different set-ups that may move the issues around but don't totally eliminate them. One bar we played in regularly always soaked up the bass, making it almost non-exsistent in parts of the room. One sub, two subs, or four subs, put next to each other, spread apart, the back of the room always lacked a good bass tone.
     
  13. Also placement is often very limited, due to stage sizes and the space allowed for the band.
     
  14. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Well, you can either add more stuff that causes it or you can eliminate as many things that cause it as possible. The choice is yours.
     
  15. Dantreige

    Dantreige

    Oct 22, 2009
    Wisconsin
    Do you (or the band you are listening too) aways split the cabs on sticks? This could be the cause of that.

    Sometimes it is better to stack both boxes on one side.

    Small rooms are the hardest to mix in. Unfortunately, small rooms are home to most of us semi-pros. Every sound source (bass cab, guitars, keys, vocals, etc,) are adding to the sonic mess. Also, most musicians are unaware of the issues they can cause by taking up too much sonic space. (Frequency Slotting: http://www.talkbass.com/forum/f203/band-mix-solo-tone-frequency-slotting-805758/ )
     
  16. Steve

    Steve

    Aug 10, 2001
    I do not recall ever seeing anyone set gear for single source point sound. IF there is a stage, it gets stacked left right. Joe's bar, The Eagles and 20 others in Orlando, Steely Dan and 20 other's at The St, Augustine Amphitheater. about 50 or more at The Florida Theater...

    Once in a great while I'll see someone stack subs center but even then you get 6 or 8 double eighteens side by side and your source is 15-18' wide while you won't set your SVT cab on the side?

    I think the vast majority of us get stuck where the management say's we get stuck and we put the stuff where the management let's us put stuff. None of those decisions are predicated on sound. They are determined by how many tables they lose or how many people complain about near field volume.

    My experience is that what we are discussing is at best an intellectual exercise and what my Grandfather, who spent much of his life as a sound engineer for RCAwould call, " Shoveling S#$t against the tide"

    IMHO YMMV
     
  17. Coolhandjjl

    Coolhandjjl Supporting Member

    Oct 13, 2010
    Appleton
    The proliferation of PA's on Stick has allowed those with little or no understanding of SR get into the act. And that, sorry to say, includes the bands themselves who have their own.
     
  18. Steve

    Steve

    Aug 10, 2001
    You just described 98% of the people in the music industry.

    IMHO

    Don't forget venues that won't permit a mix position in the sweet spot or a sound tech that won't walk the room to hear the differences
     
  19. Pole mounted main speakers on a pole coming out of the subs? Another bad idea? This is how JBL and Yamaha, among others, seem to advertise as this being the way to set up their PA speakers.
     
  20. Dantreige

    Dantreige

    Oct 22, 2009
    Wisconsin
    Companies sell what they can sell. Just because it is a bad idea does not mean they will stop selling products that are designed poorly.

    I need to pay some bills atm, so I'll address your question about poles on subs later today.
     

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