Project P/S SHIVA - Need all DIY'ers

Discussion in 'Archived Threads 2001-2004' started by KyleGS, Oct 12, 2002.

  1. KyleGS

    KyleGS Second Unit

    Feb 12, 2002
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    Here's my my project: Need a few pointers...

    Shiva- building a 3.17cf (~90L) for the Shiva with .75in mdf then covering it in .75 in real wood. Therefore the cabinet will have 1.5in walls all the way around.

    It will be a ported/sealed application (downfiring).
    It will be 3.0cf net tuned to 19hz. (very similar to Adire alignment).

    1)How do you plug a port to seal it COMPLETELY. I'm using a 3in flared port. I'm nervous about the port leaking.

    2)Does the port affect the sound of the sealed box with port plugged? Does it resonate/vibrate etc...

    3)Do I need internal bracing with 1.5in walls?

    4) Is a total Q of .64 too LOW for my audio needs? (my main concern) I hear you should shoot for .707 for audio.

    Any other advice for this project would be greatly appreciated!
  2. charles_w

    charles_w Stunt Coordinator

    May 11, 2001
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    If you use 3" schedule 40 pvc pipe for the port you can get an expandable rubber plug for it at Home depot. I'm not sure if it would seal completely using a flared port.
    I would highly recommend internal bracing.

  3. Chris Tsutsui

    Chris Tsutsui Screenwriter

    Feb 1, 2002
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    Yeah the PVC pipe plugs at home depot will work, it's basically 2 metal discs with a rubber grommet like thing between, You just tighten the wing nut and the plates compress the rubber grommet to expand making an air tight seal.

    I recommend .75 inch walls braced since a 1.5" wall will not only make the box much heavier (possibly over 200lbs) but could still have panels that resonate due to the large surface area. The braces don't have to be the kind Adire uses, but can be strips of MDF along the sides that meet, or right triangles in the edges that help prevent that "booming" noise when you knock on the sides.

    There is no perfect Q for everyone, I generally like a high Q in my car while I prefer a low Q for my home theater. Most of it depends on whether you like home theater / rock bass with a punch, or audiophile, smooth, string bass.

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