Do you need to stack cabs to get a coupling effect?

Discussion in 'Amps and Cabs [BG]' started by rabid_granny, Oct 20, 2003.

  1. I read in all of the threads that if the cabs are within 1/4 wavelength away, the soundwaves will magnify one another, correct?

    Do they have to be stacked to get that effect? Can they be placed side-by-side? Speakers are round so the soundwaves should be pushed out in an omni-directional fashion.
  2. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    generally you're gonna find a lot more clarity and definition bu stacking cabinets than you are putting them side by side
    i have known this for a while but was knocked out recently at a rehearsal where i was too lazy to stack my bag end 15 and 12
    even seated the sound was less than good
    i finally got off my butt and stacked the cabinets and holy moly
    i dont remember all the physics involved but it makes a difference
  3. Phat Ham

    Phat Ham

    Feb 13, 2000
    No, they do not have to be stacked.
  4. BruceWane


    Oct 31, 2002
    Houston, TX
    Coupling doesn't require cabs to be stacked, but they do need to be fairly close together. Side by side gets you more interaction with the floor, somewhat like moving your rig nearer to a back wall. It'll tend to enhance lows at the cost of clarity, and may be too boomy. But it's worth a try. You won't lose any volume versus stacked.
  5. Stephen Soto

    Stephen Soto

    Oct 12, 2003
    I would stack mine if I had a 1x15 and 4x10, or 2 4x10's or whatever...
  6. I experimented with this very thing.

    The big difference is that you will hear the top cab better when it is elevated. What you may find is that you are turning the cabs up a touch louder to hear the same attack and punch that you would expect when the cab is elevated.

    The closer the speakers are to your head, the louder they appear...

    This would only tend to be noticed while you stand right in front of your cabs (which most of us tend to do on smallish stages) as you move away from the cabs you will notice the difference far less.

    The reality is that room accoustics vary so much that what works in one room may sound dreadfull in another...

  7. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    I agree with the "elevation" theory. I can hear myself much better, and have better clarity, when my 4x10's are stacked. I usually bring both 4x10's to gigs, even when I only play through just one of them on smaller stages, using the other one just as a means to lift the other off the floor and closer to my ears.
  8. Eric...thats just rude..
    A 4x10 as a speaker stand...:D
  9. Mutual coupling occurs when the drivers are within 1/2 wavelength of each other.

    The drivers can be 5.63 feet apart and still couple from 100 Hz and down.

    1128/100 = 11.28 foot wavelength
  10. You do, however, want to keep the cabinets as close as possible to avoid phase smear between them. You can get mutal coupling on the lows and totally screw your mids and highs if your cabs get far enough apart from each other.
  11. notanaggie

    notanaggie Guest

    Sep 30, 2003
    When you stack, you get some coupling effect, but you tend to lose lows relative to setting side-by-side.

    But the clarity is better both because you are closer to the cab, and also because out front, you don't get as much phase smear, or at least it stays pretty much the same.

    if you walk around in front of side-by-side cabs, you get all kinds of varying smear as you are moving to different distances from each speaker.

    Stacked, the change is usually quite a bit less, (unless you climb stairs) because you tend to stay at the same height.

    So for max boom, leave on floor and even take off casters or set cabs on sides.

    For clarity and projection, stack.

    My 0.02
  12. Stephen Soto

    Stephen Soto

    Oct 12, 2003
    lol :p :rolleyes:
  13. Petebass


    Dec 22, 2002
    QLD Australia
    What happens when you put one speaker cab directly in front of another?
  14. Also, does it matter which direction the cabs are facing? What is the cabs are stacked by pointing different directions, let's say by about 20 degrees?
  15. wneff

    wneff Supporting Member

    May 27, 2003
    Woburn, MA
    There are two or three parts of the story.

    Part one is already discussed: Elevated speakers can be heard better.

    Part two: A speaker on the floor produces slightly more bass than elevated since you get a reflection on the bass frequencies from the floor (I think 1.5 db or so.)

    Part three: Well, coupling is not a magic trick. You get quite a bit louder through stacking, but energy conservation is still in effect. Where the higher efficiency in front of a speaker comes from is a loss of efficiency towards the sides.

    Please, all you audio guys, correct me if I'm wrong here:

    One single speaker radiates bass approximately in the full half-space in front of the membrane, without much discrimination what's front and what's side (middle and treble are more towards the front).

    If you stack two, the radiation field becomes ellitical. In particular, if you have two speakers on top of each other, the radiation towards the ceiling and towards the floor are supressed. This is helpful because you reduce reflections from the ceiling and you don't get the floor shaking as bad (pick up from other microphones is reduced - less coupling from the floor)

    This energy is bundled forward. Where a point - like source like a single speaker would fall of rapidly with distance, the stack of two will drop off less rapidly and carry the sound much further.

    I usually have my speakers stacked on top of each other, except when I want to make my system look small.


  16. Rockbobmel

    Rockbobmel Supporting Member

    I just saw a Mesa RR 2-15 for sale + I think I'll buy it to put under my Powerhouse 1000 (1-15 & 4-10) cab. Will I get more ooommphhh with this stacked?
  17. I'm still trying to visual this coupling thing...with that said, if this gets too complicated, my head will explode and I'll be content to let this thread just DIE!!!! :bassist:

    So, I've made a diagram, does either scenario A or B describe the coupling effect? Sorry about not incorporating ellipses but I just totally forgot.

  18. Petebass


    Dec 22, 2002
    QLD Australia
    Actually Granny, your diagram labled "Mutual coupling A" looks more like a diagram of Phase cancellation.

    CLICK HERE . T think the diagram you're searching for is the one on the far left.
  19. Okay, that's a bit better. But I'm still trying visualize what Wneff meant by "If you stack two, the radiation field becomes ellitical. In particular, if you have two speakers on top of each other, the radiation towards the ceiling and towards the floor are supressed."


    Sidenote: Petebass, you grabbed that explanation from my university, Simon Fraser University!
  20. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    Also, keep in mind sound waves are compression waves, not up and down like water waves.