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Stacking Cabinets, Coupling, Comb Filtering With a Twist

Discussion in 'Amps and Cabs [BG]' started by RColie, May 1, 2009.

  1. RColie

    RColie Supporting Member

    Nov 21, 2007
    St. Louis, MO
    I sometimes play through a pair of UL112s, stacked on top of each other. I've seen plenty of threads talking about the benefits of stacking identical cabs vertically - the cabs couple for better low end, and the stack avoids phase issues and comb filtering.

    BUT, I play in a trio with a drummer and guitarist, and we play fairly complex and sometimes unstructured music, so it's imperative that we are able to hear each other on stage. My band mates have asked me to turn the top UL112 about 30 degrees toward them so they can hear me better (that is leave the top cabinet on top but just rotate it a bit).

    Does this roatation of the top speaker then cancel out the benefits of speaker coupling and the avoidance of comb filtering? It sounds OK on stage for me but I don't know what the audience is hearing.

  2. KJung

    KJung Supporting Member

    My guess is that every B# you play will sound like a C natural out in the audience. Close in, there should be no problem:D
  3. RColie

    RColie Supporting Member

    Nov 21, 2007
    St. Louis, MO
    Nothing that can't be fixed with a good tuner:D:D

    I can always count on you for either really sensible advice or a good laugh!
  4. Foamy


    Jun 26, 2006
    Sac Area
    You just wasted about 4 seconds of my life when this hit me.
  5. KJung

    KJung Supporting Member

    Sorry.. I couldn't help myself.

    Seriously, my guess is that since mids are directional and bass is not, there will be a bit less mid presence in part of the room where the top cab is pointing away from, and a bit more in the part of the room where it's pointing toward. I wouldn't worry too much about it.

    Bill F. or Alexclaber or Greenboy, etc. will show up and give you the exact info on this.
  6. ettsn


    Mar 29, 2009
    Atlanta, GA
    There are degrees of phase involved here, and short of doing the math, I would recommend either asking someone to play your rig or use a long cord (or wireless) and see for yourself. Probably see very different results based on only a few degrees difference in offset angle.

    Could the issue be solved with better monitors or in-ears?
  7. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I've had to do it in the past, but usually just better stage layout and rig placement can deal with the problem you mentioned better...

    You'll still have coupling at lower frequencies, but you are making all kinds of frequency-specific lobes and nulls in the midrange and up. But then, there's always stuff that someone needs to hear in the audience area to estimate whether its a worse problem this way or that.
  8. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Not if you turn the cab far enough, which usually means at least 45 degrees. Problems arise in the audience when mids and highs are heard from two sources which are horizontally arrayed. If the top cab is turned enough the audience can only hear the mids and highs from one cab or the other and there's no problem. But there is a better way. If you have a decent monitor system run the bass through the monitors, high-passed on its channel strip around 300 Hz. That will give the rest of the band the mids and highs they can't hear from your cab without putting anything low in them that would only muddy things up. Below 300 Hz the output of your cabs is omni-directional and they'll hear that from your cabs no matter which way they're aimed.
  9. RColie

    RColie Supporting Member

    Nov 21, 2007
    St. Louis, MO
    Thanks for the replies. The bass doesn't go through the P.A. because the speakers can't really handle the bass. But you guys gave me some ideas to try. I think I'll keep the cabinets stacked as they should be and work out something else for the drummer and guitarist.
  10. RColie

    RColie Supporting Member

    Nov 21, 2007
    St. Louis, MO
    That sounds like it would work, thanks! Cutting the frequencies below 300 Hz would allow me to come through the monitor system without distorting it. I'll give that a try.
  11. I've wondered about this myself - as I've faced a top cab towards the drummer so he could hear me.

    I also wonder about the Schroeder cabinets how they have speakers that are angled combined with forward facing ones. I guess the baffles help project the sound the right way - but I always wondered if there were phasing issues with that design.

    Btw - there's another way to make everyone hear you, turn your rig 45 degrees towards them, and crank that sucker up! I know there's one room I play where people say they can't hear the bass very well directly in front of the stage (say 30' away) - and the cab is facing directly at them. However, off to the side of the stage at the bar 40' away), the bass is LOUD. So I guess the room can matter more than which direction you face your cab...

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