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Questions about round box port

Discussion in 'Subwoofer Box and Custom Fabrication' started by Fi fan, Feb 3, 2011.

  1. Fi fan

    Fi fan Full Member

    I have 2 FI BL 15s and im planning on putting them on a audiopipe 3k but im building a new box for them and im wondering if putting a round port on the outside of the box is going to give the same result as putting it on the inside. the reason for doing this is because I have only a limited amount of space and im trying to get as many cubic feet as i can.
    thanks
     
    Fi fan, Feb 3, 2011
    #1
  2. Ranger SVO

    Ranger SVO Full Member

    It makes no difference if the port is in or outside of the box.

    The tuning will change slightly due to the increased air space (port outside the box), but again it should not be a problem
     
    Ranger SVO, Feb 3, 2011
    #2
  3. TheViking

    TheViking Well-Known Member


    This is true!
     
    TheViking, Feb 3, 2011
    #3
  4. connerray2010

    connerray2010 Full Member

    how do you tune for two (2) ports? i have 2 4" ports so i just put the port diameter as 8" and then cut the overall length i n half. does this work? or do i need to figure in 4" diameter then double the length? which is it? neither?
     
    connerray2010, Feb 3, 2011
    #4
  5. Fi fan

    Fi fan Full Member

    Thanks guys. and sorry connerray2010 i wish i could help but i don't know how that would work. wish i could help tho.
     
    Fi fan, Feb 4, 2011
    #5
  6. Ranger SVO

    Ranger SVO Full Member

    Two 4-inch ports is equal to a single 5.656-inch port. It would take four 4-inch ports to equal a single 8-inch port.

    The method we use for adding round ports together is called Combined in Quadrature. Take the port diameters, square them then add them together. Finally take the square root of the sum and you have your answer.

    Below is an example for two 3-inch ports which equals a 4.24-inch port
    and an example for three 4-inch ports which equals a 6.92-inch port
     

    Attached Files:

    Ranger SVO, Feb 4, 2011
    #6