How bad of a room am I in?

Discussion in 'Archived Threads 2001-2004' started by Leif Wall, Apr 11, 2002.

  1. Leif Wall

    Leif Wall Second Unit

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    I've got a single 20-30cs right now, living with my parents and it's in the living room. Will only be here a few more months, but was wondering if this room is a 'subwoofers worst nightmare' type of deal.
    20ft x 20ft with a 8ft ceiling
    On one side is a 8 foot opening into the dining room. In the back a stairway leads well, upstairs. [​IMG] I basically set it up where my soundfield takes up half the room and the sub is in kind of a 'quasi-corner' type of deal. (A 2ft section pops out in the middle of the room.)
    So, is this a tough room?
     
  2. Richard Greene

    Richard Greene Stunt Coordinator

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    Impossible to predict from here.

    Rough predictions can be made about well-sealed

    rectangular rooms -- but other types of rooms need to be measured before coming to any conclusions.

    The way to find out is to use a slow frequency sweep tone and Radio Shack sound meter to measure the frequency response deviations at your listening position (deviations caused mainly by standing waves, not by the subwoofer itself)
     
  3. Chris S

    Chris S Cinematographer

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    Chris S
     
  4. Richard Greene

    Richard Greene Stunt Coordinator

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    Standing waves cause both frequency response peaks and troughs. The peaks are much easier to hear and have much more of a negative effect on the sound quality.

    Standing waves (aka "room modes") are determined by room dimensions.

    The location of a speaker determines how much each room mode is excited. Only a speaker in a room corner

    will fully excite all room modes.

    The location of your ears determines how well you can hear room modes. At some frequencies you may hear loud frequency response peaks and at other frequencies you may hear very little output (frequency response troughs).
     
  5. Leif Wall

    Leif Wall Second Unit

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    Just did the LFE sweep on Avia. Seems I have a couple of nasty peaks around 70hz and 50hz. Once it hits 30hz reponse drops off considerably. It seems like the SVS is trying to push a lot of air, but you can't hear of feel anything at the seating position. You can hear the grille vibrate softly similiar to certain scenes in the Haunting DTS ES.
     
  6. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Leif,

    I would say then that, perhaps, your location is not the better for bass. Try to run the sweep and walk around the room. Chances are that you will be hear and feel the content at less than 30Hz, your apparent actual limit.
     
  7. Leif Wall

    Leif Wall Second Unit

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    It sucks because it's the only place I can really place my sub. Only a few more months I guess and it's not like it sounds bad, but I'm sure it can sound a lot better. On movies I have to be getting good response under 30hz though, as movies like Episode 1 get crazy.
     
  8. Richard_s

    Richard_s Second Unit

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    Don't know where you have the SUB but if it is in a corner and you have the main driver too far from the walls this can cause interfearance which is what you seem to describe. The article I read and it did help my system was that the Driver needs to be within 21 inches of each wall to avoid interfearance. Just what I read, seemed to work for me and I use AVIA and SPL meter from radioshack also. Just set up last night though so not alot of listening yet.
    Link to article on Sub Placement:
    Sub Placement interesting
    I did not try this yet but maybe useful information even though you have a limited choice on location.
    Link to a method may help
     

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