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Does room size affect how low the subwoofer can go?

Discussion in 'Archived Threads 2001-2004' started by Ariel, Aug 27, 2001.

  1. Ariel

    Ariel Stunt Coordinator

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    hi to all!
    my room is about 17' x 13' x 9' (L,w,H). i am wondering
    if i use a sub that is capable of reproducing 20hz and below like the servo15, will i hear or feel these frequencies? if not then i can save some money and buy a smaller sized sub that can just go to about 24hz.
    thanks in advance.
     
  2. Ned

    Ned Supporting Actor

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    Headphones can do 20hz. Those are a pretty small "room". Room size doesn't matter (except if it's huge of course, but that's another issue).
    ------------------
    My Home Theater Page
     
  3. Ariel

    Ariel Stunt Coordinator

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    thank you very much. i just become confused when i read
    from another forum that the room size is a major factor
    on how low the subwoofer can go.
     
  4. MarkO

    MarkO Second Unit

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    Small rooms do limit the low end. Im not sure exacaly how. Maybe Tom V will chime in here. My guess is that small rooms hinder the long wave needed to reproduce the really low stuff because of early reflections.
     
  5. Dirk E

    Dirk E Auditioning

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    Hi MarkO,
    sorry, but what you wrote is incorrect. One of the SVS-people explained this "small room, low bass"-thing a few month ago.
    You can get a lot of deep bass in a small room, a car or even a headphone. Size doesn`t matter. Small rooms tend to boost low frequencies. Believe me, my room is only 10m² and I get a lot of deep bass down to 20 Hz.
    I hope Tom or Ron can explain it again in more detail.
     
  6. Bob McElfresh

    Bob McElfresh Producer

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    Here is my Understanding (open for discussion/debait) [​IMG]:
    If your sub can go 20 hz, you will hear 20 hz.
    But in a normal room, you are hearing 2 types of sound:
    - Direct
    - Reflected
    Much of the time, the walls of the room will reflect several frequencies much better than others.
    Here is how to calculate the frequency a wall will reflect:
    Measure the long, un-broken wall in feet. Let's say 8 feet, 6 inches. This becomes 8 + (6/12) = 8.5 feet.
    To get the frequency that this wall will reflect better than others, do this:
    frequency (base) = 565/L = 565/8.5 = 66 hz.
    But wait, that wall will also reflect 2/3/4 times this base-frequency quite well. So the wall will enhance all of these frequencies:
    66, 133, 199, 266 hz
    Take a smaller 5 foot wall, the numbers become:
    frequency (base) = 565/5 = 113
    So this wall will enhance:
    113, 226 hz
    (Note: We stop calculating at about 300 hz or after 4 frequencies).
    So a small room wont ENHANCE the lower-frequencies like a room with longer walls will.
    Now lets analyze your room:
    17' wall: 33, 66, 100, 133
    13' wall: 43, 86, 130, 174
    9' wall: 63, 126, 188, 251
    So the room will ENHANCE: 33, 43, 63, 66, 100, 126, 130, 133
    But if you listen to pipe-organ music, the sub will still produce 20 hz sounds. It just wont get help from the room until about 33 hz.
    Hope this helps. [​IMG]
     
  7. Ariel

    Ariel Stunt Coordinator

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    thanks bob. that is a very good explanation and a big help
    for me.
     
  8. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    I see much has been explained.
    Generally,the larger the room...the smoothed the bass will be over a variety of seats because of the mode spacing. The smaller the room, the more *room gain* will allow the subwoofer extend lower.
    Tom Nousaine acoustically mapped his old(2136 cu-ft) room and compared it to the mapping of his new (7500 cu-ft)room in a SR piece a while back. He found the smaller room increased 20hz bass performance 8.1dB and 25hz bass performance 3.6dB.
    I believe 16hz was 11.5dB.
    TV
     

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