Help tuning my 10" AA Assassins

[dr_evo]

this is the first ported box that i have owned. the measurements are 31.75 x 13 x 16.5 which i calculated to be 3 cu.ft. the ports are both flanged and the pipe is 4 inches in diameter and 17 inches in length. i calculated the port to be 24hz and the specs for the AA assassin is 32hz. I ran the calculation from the 12volt.com and found that my port length should be at 8.1 inches to achieve 32hz. what i dont know is how do i take into consideration the volume of the port and the variance of the flanges or are they negligible? i know that those also affect the cu volume of the box but i just have no idea how to calculate it.

any help is appreciated.

oh yeah i forgot to mention this is for 2 10" assassins

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[helotaxi 5,000+ posts]

Assuming the dimensions that you gave are external, the net result of what you have is around 2.6 cf tuned to about 36 hz. Should work pretty well for those subs.

I'm guessing that since you said ports you have 2? You have to account for the number of ports that you have when you calculate port length. More ports means more length for the same tuning. Also to figure how much space the port displaces, find the volume of the port that is inside the box (pi*R^2*L).