Need help with car sub enclosure

Discussion in 'Home Theater Projects' started by Ned, May 7, 2003.

  1. Ned

    Ned Supporting Actor

    Feb 20, 2000
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    Due to size constraints, I have to reduce the size of the sub enclosure for my car. The shape is roughly like this from the side


    I estimate the internal volume around 0.5 cubic'

    The driver is an Eclipse 86120.4 and the parameters are

    Fs: 28hz
    QTS: 0.75
    VAS: 3.06 cubic'
    RE: 4 ohms
    QMS: 11.5
    Qes: 0.42
    Xmax: 1"
    Sd: 485.5

    Eclipse suggests the following designs:

    0.5 Sealed - "competition"
    1.0 Sealed - "boomy" (heh, desirable?)
    1.25 Sealed - "Nat bass" (natural I guess)
    1.75 Sealed "Ext bass" (extra or extended?)

    What happens as I reduce the enclosure volume? Less extension but more SPL? Before the box was twice this size (I sawed it in half), and the sound was a tad "loose", with "overhang". Is this "competition" design what people call "punchy"?

    I also have one of the old SVS 12" CS/PC drivers leftover from the driver upgrade. Is that driver much better than this Eclipse unit and suited for such an enclosure?

  2. Chris Tsutsui

    Chris Tsutsui Screenwriter

    Feb 1, 2002
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    I think the smaller box will sound tight and punchy, and also not be able to hit deep bass notes. The small amount of air in the box somewhat limits the movement of the driver acting like a spring, unlike an infinitely large box where the sub can move freely.

    Generally ppl associate the boomy sounding competition subs with distortion. I think the big sub has "extended" bass due to the fact it probably is capable of the deepest bass.

    Competition subs sometimes have huge humps in the response which determines their "competition frequency". Your new 0.5 sealed sub may have a hump in it therefore giving you some chest pounding impact. At the same time, your new box will not be capable of the real deep bass notes it once hit, and instead sound more one-tone.

    Some amps have adjustable "Q" bass settings that can artifically change how "tight" your sub sounds.

    Good luck

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