subwoofer problem with new home theater

Discussion in 'Home Theater Projects' started by Brian-K-Owens, Oct 22, 2003.

  1. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

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    I have a BIG problem.

    Finally finished my home theater, and everything is great except one problem:

    Bass sounds great everywhere in the room except where I want to sit!!!! It seems as though the bass sounds great when I am standing up in front of my chair, but is terrible when I sit down. As my ears get closer to the floor, the bass begins to sound worse. It is like it disappears and becomes a dead thump.

    I quick run down on the setup:
    a pair of tumults in the 2 front corners of the room. They are sort of built into the wall. There are openings in the wall slightly larger than the enclosures that the subs slide into. This was a WAF setup, so it cannot be changed. I have a BFD, but not tried to EQ yet. I have it set with a little boost around 20-25Hz right now.

    The room is 16 ft wide, and 20 ft long. I sit back about 16-17ft from the front of the room.

    The room has hardwood floors with no rugs yet. . .not sure if that has anything to do with it.

    I have also checked all wiring, and have tried playing one sub at a time. . . no improvements.

    Any help or advice appreciated.
    Brian
     
  2. mark alan

    mark alan Supporting Actor

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    I had the same problem. I moved the chair
     
  3. ThomasW

    ThomasW Cinematographer

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    Obviously the 'sweet spot' is located in a 'null'.

    One can't use EQ to boost a null, it's like pouring water down the drain.

    Options are, move the subs or move the chair.
     
  4. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

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    does driver orientation matter? If I change them from front firing to downfire, would that help????? Seems like the worst part of the null is when my ears are at the same height as the subs.

    Looks like am going to be standing up watching TV a lot. . . .

    Brian
     
  5. ThomasW

    ThomasW Cinematographer

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    Can't hurt to give it a try. Don't hold you breath though...

    Is the 'fit' in the wall loose enough to angle the boxes in slightly? If so try that as well.
     
  6. Greg_R

    Greg_R Screenwriter

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    Try elevating the subwoofer (use a few cinderblocks as a temporary measure). Can you try stacking both subs in one corner of the room as well?
     
  7. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

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    I did a few things real quick last night, and it is getting better. With a little more time, I think it will be acceptable. . .

    First thing I thought I would try was to do a quick frequency response plot without the BFD to see where I was at the listening position. When I turned the BFD off, what a difference. The bass was MUCH smoother at the listening position. Only thing I can figure out, is that I had too much boost at 20-25 Hz causing 35-40 Hz to be a larger null than is there without any boost. Is that possible? Another thing that surprised me is the frequency response of these subs without any EQ!!!! They are in 2.5 ft^3 sealed and man do they sound good.

    Second thing: moved the chair back 12". Not as much improvement as the BFD change, but a little more improvement.

    third thing: tilted the subs back and forth. Hard to tell if there was any improvement. Maybe a little when the subs were tilted outward.

    As it stands right now, the listening position is not the best position in the room, but it is VERY acceptable now. I still need to run the SPL/frequency plot and see if I can further improve with the BFD.

    Thanks for all the help guys!!!!!
    Brian
     
  8. Greg_R

    Greg_R Screenwriter

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  9. Dave Poehlman

    Dave Poehlman Producer

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    I was going to say they may be cancelling each other out. You may be sitting in an area where the soundwaves from each are 180° out of phase with one another. Try turning one off to see if there's an improvement. That will tell you that there's a phase problem. Or... (I'm not sure how you're powering them) if your amps have a phase control, try switching one 180° out of phase with the other... this will probably cause problems in other areas of the room, however.

    Also, if there's some furniture in the way when you sit down.. a loveseat for example can act as a big bass trap. I know because I once had my sub behind a couch due to room constraints and I could only hear it fully in a location where I had a direct line of sight with the sub... I bought a new house to solve the problem. [​IMG]
     
  10. Wayne A. Pflughaupt

    Moderator

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  11. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

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