Calculating port displacement?

[Gater]

Ok so I'm building a box for a single 12" AB hd and I need to calculate the port displacement so u can figure the net volume. The box is 33"w*16h*16d with .75" mdf. 12volt.com says that 33x16x16 and .75 is 3.8^3ft. My port is labyrinth style and is 4" wide by 14.5 deep and there is 3 sections to the labyrinth, so it's about 40 inches long from the opening in the box to the ending edge if the 3 piece if wood that make up the port. As I said I'm trying to figure out port displacement so I can add that to sub and bracing displacement to find my ending box volume. I've searched everything u could find and can't find any information on how to calculate the displacement if a slot port or I wouldn't ask. Thanks in advance.

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[garychoffmann 10+ year member]

Just measure the total port area and multiply length x width x height (in inches) and divide that by 1728. Without knowing how many turns and shared walls it has its hard to calculate. 4 x 14.5 x 40 ÷ 1728 = roughly 1.35 cu/ft

 

[Gater]

Just measure the total port area and multiply length x width x height (in inches) and divide that by 1728. Without knowing how many turns and shared walls it has its hard to calculate. 4 x 14.5 x 40 ÷ 1728 = roughly 1.35 cu/ft

Thanks so much. Yea it has 2 total turns and 3 lengths of port 2 are 14."5 and the 3rd wall ends at 10.5" (all the walls if the port are 10.5") and 2 shared walls, the other walls are the side if the box and the inside most wall is shared my the actual subwoofer space. Thanks again for letting me kno the equation to figure it out.

 

[garychoffmann 10+ year member]

No problem man, good luck