Will there be phase problems if two subs are spread apart but allong the same wall?

Discussion in 'Archived Threads 2001-2004' started by jeff lam, Dec 19, 2001.

  1. jeff lam

    jeff lam Screenwriter

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    When I get around to building my 2 shiva sonosubs, I would like to place them each behind my main speakers on each side of my entertainment center along the front wall. I do not have a suitable corner in the front of the room. Will I run into any phase issues? They will be about 7-8 ft appart on a 14 ft wall.

    I hope the picture/diagram comes out OK.

    front wall

    --------------------|

    this O subs O |

    side |sliding glass door

    is |

    open |

    1

    1

    sofa 1rear corner

    ---------------------

    Oh well, just move the (|)'s and (1)'s over to the right to make the right wall.
     
  2. Greg Monfort

    Greg Monfort Supporting Actor

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    At 8ft, they will combine as one from ~53Hz on down. Above this point there will be some comb filtering, but I doubt you'll hear it for all the room mode interaction of mid wall placement.

    GM
     
  3. Wayne A. Pflughaupt

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    Jeff
    You can expect cancellation at specific distance-related frequencies with this set up. There will be interaction between each sub and the side walls, as well as the walls opposite them. In addition, the subs “see” the half-way point between them as a boundary. You can determine the frequencies with the formula 1130/DX.3 (where D=distance).
    If at all possible, Jeff, it would be much better to put both subs in a corner. I made a post last night discussing this in detail. You might want to look at my 1st and 3rd posts at this link:
    http://www.hometheaterforum.com/htfo...threadid=32850
    Happy Holidays,
    Wayne A. Pflughaupt
     
  4. Scott Page

    Scott Page Stunt Coordinator

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    Wayne,
    A question on just what is the best way for placing two BIG subs in the same corner. You have been a big help to me and I appreciate it. If you remember I have a 24" Tempest sub and a second one under construction. With subs that big one of them would obviously be a couple of feet at best from the corner.
    So do you know what is best?
    One sub directly in the corner a few inches from the walls to prevent vibrations, and the second one next to it against one of the walls, back or side, or
    the second sub directly diagonal to the corner and the first sub, or
    should you place both subs on the corner's adjacient walls each being equal distance out a couple of feet from where the walls meet in order to fit them both in?
    Does that question make sense?
    I suspect you will tell me to try them all and test. If so, can you also tell me how to get the wife and kids out of the house all weekend? [​IMG] She would kill me being home with all that racket - know what I mean?
    Cheers, Scott
     
  5. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    One on top the other.
     
  6. Scott Page

    Scott Page Stunt Coordinator

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    Not possible. Mine are nearly 6 feet tall each.
     
  7. Greg Monfort

    Greg Monfort Supporting Actor

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    Put one in the corner and the other next to it along whichever wall is most convenient/looks best as their BW WLs are so long it won't make any difference. If you prefer to place one on each wall for appearance sake, you will probably need to stuff the corner cavity as it becomes a harmonic pipe of sorts. I have bipolar subs that bridge the two corner walls and had to pack the cavity with rolls of fiberglass.

    GM
     
  8. Scott Page

    Scott Page Stunt Coordinator

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    Thanks Greg!

    That is just the type of info I was looking for.
     
  9. Wayne A. Pflughaupt

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    I’ll second Greg’s advice, Scott. I had the same problem when I put both my subs in the same corner (i.e., aesthetics). I ended up laying them on their sides and stacking them. The top speaker is about 2ft. off the ground, but it worked fine.

    Interesting about the “harmonic pipe,” Greg. How did it manifest itself? Did you take any measurements, or was it mainly “seat of the pants?”

    Happy Holidays,

    Wayne A. Pflughaupt
     
  10. Greg Monfort

    Greg Monfort Supporting Actor

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    The 1/2, 1WL peaks were audible to me as coloration in the lower mids, but I have a very HE system. Whether it would be noticeable with a typical cone/dome system or is measureable I can't say since I only have 1/3octave resolution at the moment.

    GM
     

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