box calculations

[big_mofo 10+ year member]

ok so im tryin to figure out the port length for my box, which will be 8cuft tuned to 33hz. i did the equation(LV=[(1.463x10^7xR^2)]/[(Fb^2xVb)]-1.463xR) well R^2=7in, Fb^2=1089, Vb=13824. and the length i got was 37in. does that sound right, if not what do i need to do? thanks for any input.

Chris R.

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[xluben 10+ year member]

how big is the port?

what units are your measurements (all in inches)?

 

[big_mofo 10+ year member]

how big is the port?
what units are your measurements (all in inches)?

it will be a dual chamber box, and 3.5in port width on each side. each sub will have roughly 4cuft, and yes all the measurments are in inches. the first equation was done for a box with one port and last night i redid it for a box with 2 seperate ones and got a Lv of 18.6in. if that makes no sense ill put the 2nd equation to show you.