how far off walls for sub is good?

Discussion in 'Speakers & Subwoofers' started by al lout, Dec 18, 2004.

  1. al lout

    al lout Stunt Coordinator

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    I have a DIY sealed Tempest sub in a 15x15x9 room with 2 openings (1 to the kitchen and 1 is a hallway). I'm trying to achieve a flat response for my sub. So far I have moved the sub in 2 different positions and have noticed a huge different.

    1. First position, sub is right next to the right of the sofa. It sat at about 2' off the back wall and 6.5' off the side wall. At this position, there're 2 nulls/deeps at 40hz and at 75hz (about 23db drop). Reading at 20hz is 98db and from 25-100hz excluding the 2 nulls avg at about 104db.

    2. Second position, sub is in the corner on the right of sofa as well. I am currently have it there. It's about 1.2' off both walls. With this position, there is no null spot (a small deep at 72hz of 6db). Reading at 20hz is 94db, and from 25hz - 100hz avg at around 106db.

    From the 2 positions above, which position should I keep? I can't place the sub anywhere else or it will look awkward. What I can do is move the sub a few inches in/out off the walls. Question is how far off the walls should I place my sub to achieve a flatter response? From position #1, my sub is louder/ more shaking to the building. But the 2 nulls/deeps kinda convince me to put it at the corner. In the corner, the sub is a little boomy. As I don't want to move the sub too much, it's more than a hundred lbs. What do you guys suggest? Thanks in advanced.

    Al,
     
  2. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    When you tried the corner placement, did you also recalibrate? Often, folks mistaken think corner placement = boomy because it will lead to great bass output from the subwoofer. So if they don't recalibrate...when they give the new position a listen...the bass seems a bit overwhelming/boomy at times. Also, if the amplifier you are using has a phase control...don't forget to experiment a bit with that too...that can help with dips in the range where the mains crossover to the subwoofer.

    Tom V.
    SVS
     
  3. steve nn

    steve nn Cinematographer

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    Everything Tom suggests plus repositioning the sub so the driver faces the wall. It can take many movements of 1 inch increments to achieve the best result. Good luck Al.
     
  4. al lout

    al lout Stunt Coordinator

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    Tom, thanks for the tips. I did recalibrated, first using auto MCACC on my pioneer then recheck it w/ DVE and SPL meter. It still seemed to be a little boomy on the heavy bass scene (I Robot chapter 18). I will play around w/ the phase later on. Thanks.

    Steve, Thanks for the suggestion. It's a pain to move this sub around. The darn thing is heavy. I will try to move a few inches see if it improves... will let you know. Thanks.

    Al,
     
  5. steve nn

    steve nn Cinematographer

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    If you can muster the energy try firing the driver off the wall. What I mean by that is to place the sub so the driver faces the wall. Try different angles/distance in placement. Square rooms can be a bugger.[​IMG]
     
  6. Wayne A. Pflughaupt

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    Sounds like your corner position is the place to be. Like many people here, you’d probably find a parametric equalizer the ticket for smoothing response to near perfection.

    Regards,
    Wayne A. Pflughaupt
     

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