Triple 8" subwoofers

Discussion in 'Archived Threads 2001-2004' started by Rory Buszka, Nov 6, 2002.

  1. Rory Buszka

    Rory Buszka Supporting Actor

    Jun 5, 2002
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    I have seen some subwoofer designs that use three 8" woofers on the bottom rather than one larger heavier driver. I know this is intended to respond quicker than a big 12", but do 3 drivers really improve all that much over a 12-incher? Or is this just a gimmick? I know Bose (eww) has a new transmission line triple 5.25" Acoustimass bass-module that uses high-excursion 5.25" woofers. Maybe the surface area of the 3 5.25" drivers equals up to that of an 8" or 10".
  2. Ryan Solberg

    Ryan Solberg Auditioning

    Nov 5, 2002
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    well, i'm no expert, BUT it doesn't matter how much surface area you have if its divided by 2,3, or even 4 cones.... THEY STILL WON'T BE ABLE TO PLAY AS LOW as the single cone setup with the same amount of cone area. Given the x-max of the larger cone sub isn't abnormally small.

    The multiple cone setup will probably tend to be peaky in the higher bass frequencies.... 50hz+, and then drop off pretty quickly afterwards. Of course you gotta factor in the port tuning if its in a ported/bandpass box. I don't know about you, but I'd rather have a single cone that is able to play from 20hz up, than 40-50hz and up.

    EDIT: in fact.... i have a hard time calling a speaker a sub unless it can hit sub 40hz tones....if they can't play WELL lower than 40hz then its nothing more than a midbass driver.
  3. Chris Tsutsui

    Chris Tsutsui Screenwriter

    Feb 1, 2002
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    Here's the thing with "speed" of woofers and size.

    A common fallacy is to believe that smaller drivers are "faster" than big ones.

    The only thing "faster" about smaller drivers is that they can most likely play higher frequencies.

    Since most subs get crossed over at 80hz, there is a limit to the highest frequencies they play which makes all subs equally as "fast".

    Subs are minimum-phase devices, their time-behavior (Speed, punch, drive, pace and rhythm) can be anticipated from their frequency responses. The room will also be a factor in how the bass will sound.

    Subwoofers are essentially the same in that they all move air. Using a big motor on large/heavier diaphragms is one way to get the job done. Hooking up a large number of tiny drivers is another way...
  4. Ryan, smaller drivers typically don't have the same extention as larger subs, but that doesn't mean they can't. I also don't understand how multiple drivers will result in a peaky sound up at >50hz. Can you explain

    Rory, another thing to consider on top of Chris's info (which I agree with). SPL is purely a function of displaced volume.

    Disregarding extention, lets compare the displacement of two common 8/12" subs
    TB W8-740C xmax=12mm, Sd=220cm^2 => Vd=0.53L
    Shiva xmax=15.8, Sd=481cm^2 => Vd=1.51L
    In this case 3 8"ers just barely out displace a single 12"er

    Now, if you want a sub to play to 20hz, you will have a really hard time finding an 8" that can do that. Not saying that one can be made, but it just isn't very practical for driver manufactures

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