How important is box size on a ported sub?

Discussion in 'Archived Threads 2001-2004' started by Harry Lincoln, Mar 12, 2002.

  1. Harry Lincoln

    Harry Lincoln Stunt Coordinator

    Sep 29, 2000
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    I you were to build three subs, each using identical drivers and tuning points, the only difference being cabinet size - lets say 2ft^3 vs 4ft^3 vs 8ft^3 with a tune of 16hz. What would be the performance differences between the three subs? I'm assuming you could fit the necessary port(s) into the smaller cabinet.

    I'm just trying to get an idea of how much effect the box size has on the end result.

  2. Kyle Richardson

    Kyle Richardson Screenwriter

    Jan 1, 1998
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    Just as Jack points out, download a free modeling program to experiment with. You will gain a lot of knowledge very quickly.

    To answer your question, the larger boxes will typically play deeper and be more efficient. Smaller boxes will usually not play as deep but may have more output in the midbass range. They will typically not be quite as tight sounding as well.

    Of course, these are generalities and not specifics.

    Kyle Richardson

    Acoustic Visions
  3. Dustin B

    Dustin B Producer

    Mar 10, 2001
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    Well I'm surprised niether Jack or Kyle mentioned this one. The drivers we have available today can move a lot of air. Moving lots of air in a ported sub means that you need a large port. Not a large port in length but in diameter. If the port isn't wide enough you will get port noise and compression. The minimum for a Shive would be a 3" flared port. The minium for a Tempest a 4" flared port. You could get away with a 4" straight port for a Shiva, but a flared one would be better. A 6" straight port for a Tempest would work great also.

    Now lets take a 4" port and a 6" port and model them in your box sizes in LspCAD:


    2ft^3 - 60"

    4ft^3 - 29"

    8ft^3 - 13"

    5ft^3 is an EBS allignment for a Shiva and there is no point going larger than that.


    2ft^3 - 142"

    4ft^3 - 68"

    8ft^3 - 32"

    12ft^3 is an EBS allignment for a Tempest.

    Go read the application notes for the Shiva and Tempest on Adires site and play with LspCAD to figure out the relationships between different variables some more.

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