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to cube or not to cube

Discussion in 'Home Cinema Building DIY' started by stegalv, Feb 9, 2004.

  1. stegalv

    stegalv
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    i was under the impression that dimensions of the box i am going to use to build my sub could'nt be equal on all sides (cube)but after reading various forums and seeing dimensions on some commercial subs it seems as though i can,are there any precautions i need to take in the construction, it will be 8ft^3 ported
     
  2. GaryG

    GaryG
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    The idea of offset driver's and boxes with a 'golden ratio' is to reduce the cancellation effects of the reflected sound wave off the inner surfaces of the cabinet. At the frequency a subwoofer operates at the length of the sound wave is so large that a rectangular cabinet has minimal impact on the reflected wave in comparison to a cube.

    The only consideration I would have is to put the port on the same face as the driver, probably not an issue on the size of cabinet you are going to construct, but with tube subs where the port is at the opposite end to the driver and you are sitting close to the sub it can be noticeable that the sound is coming from the port rather than the driver around port tuning.
     
  3. stegalv

    stegalv
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    hiya gary. im still running round in circles trying to understand it all.
    what do you think of the tempest box alignment on the adire website. its a net 7.55ft^3 tuned to 15.4hz.i assume with bracing and driver/amp the volume will be even lower so how is it tuned to 15.4hz?.
    it recommends 64oz pollyfill, why in a ported box.
    the site has all the specs for building the box and you said the dvc was based on the tempest so i was just wondering.
     
  4. GaryG

    GaryG
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    Best thing to do is get on a build your cabinet, use a piece of plastic drain-pipe or similar for the port and cut a number of difference lengths and have a listen or measure the response and find which one you like.

    Polyfill increases the apparent box volume, Adire have spent time optimising their design for the Tempest and have managed to reduce the cabinet size by using polyfil.

    Here's a link you might find of interest:
    http://www.win.net/audtatious/audio/fiber.html

    Although the PE driver is a clone of the Tempest it works in a smaller box, if you decide to use the Adire plans you will probably need to adjust the port tuning. Don't get too hung up on the technical details at the moment get on and build the box, you will be very happy with a wide range of port tuning frequencies, but will need to find which one works best in your room.
     
  5. Nimby

    Nimby
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    Panny 300

    Your sub will probably have internal bracing shelves which will break up the internal box dimensions into other shapes than the external cube shape. Gary's advice about low frequncies is correct anyway. Two good reasons not to worry about the external shape.

    I wonder whether the SVS cylinders split the sound up like you mention Gary? I didn't think it would be noticable except where you were very close to the sub and feeding it a wide frequncy band signal? Anybody have an SVS who could comment on this please?

    I built a few full range, folded horn, cylindrical Tricolumns and can't say I remember this vertical splitting effect even in a 'six footer' on mono. Long time ago now though.

    NIMBY
     

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