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<blockquote data-quote="BrianChia" data-source="post: 4339171" data-attributes="member: 576132">The port area depends on many different issues such as the excursion of the driver, the power supplied, and the size of the enclosure. One way to check is to go the the tabin WinISD that displays the graph entitled &quot;Rear port - air velocity&quot;, then enter the maximum power that your subwoofer will see (you MUST use the correct specs of your actual driver and also choose the correct number of subs and correct enclosure size). The said graph will display the air velocity through the vent over a range of frequencies for the amount of power you select. A good guide is to keep the peak frequency below 34 m/s, which is 1/10 the speed of sound. If you stay below this number you should not have port noise problems.A simpler guideline (though not as telling) is simply to use 12-16 sq. in of port area per cubic foot of the net enclosure volume, using more (16 sq. in/cf) if the driver has higher Xmax and lower if it has less Xmax.As for as your box is concerned, you should be fine with a 3 in. widex 14.5&quot; port. This will cut down the port length and reduce the overall enclosure size.</blockquote>

[QUOTE="BrianChia, post: 4339171, member: 576132"] The port area depends on many different issues such as the excursion of the driver, the power supplied, and the size of the enclosure. One way to check is to go the the tabin WinISD that displays the graph entitled "Rear port - air velocity", then enter the maximum power that your subwoofer will see (you MUST use the correct specs of your actual driver and also choose the correct number of subs and correct enclosure size). The said graph will display the air velocity through the vent over a range of frequencies for the amount of power you select. A good guide is to keep the peak frequency below 34 m/s, which is 1/10 the speed of sound. If you stay below this number you should not have port noise problems. A simpler guideline (though not as telling) is simply to use 12-16 sq. in of port area per cubic foot of the net enclosure volume, using more (16 sq. in/cf) if the driver has higher Xmax and lower if it has less Xmax. As for as your box is concerned, you should be fine with a 3 in. widex 14.5" port. This will cut down the port length and reduce the overall enclosure size. [/QUOTE]

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