You want to build a subwoofer box but the specs list a Gross Volume a Net Volume and Air Volume. What the heck is the difference. E nter the number of ports you are using the internal airspace of your box then tuning frequency you wish to use and then hit calculate button.
To calculate the port length of a round port enter the diameter of the port D the box volume Vb in cubic feet and the desired tuning frequency Fb.
To calculate the volume of the port first we must calculate the area of its circular cross-section. 14167 ft 3. Net Box Volume 104167 - 9. In order to account for these we will first calculate the box volume as if these panels werent there then we will calculate the two panels displacement and subtract them from the volume figure.