I am looking to build a ported box for a sub. I read the specs that the box has to meet and its totally confusing me. The only part that I understand is the volume of the box and the length of the port. The box is recommended to be tuned to 35 and I have no idea what that means or how to build that. Also port I.D. has to be 4" if anyone can tell me what that is also. And last of all the F3 (Hz) needs to be 36. I finally have a day off from work tomorrow and I really want to try and build this. ANY help is greatly appreciated. Thanks guys.

 

Will it make a difference if I make a rectangular port rather than a circular port? If I keep the volume of the port the same then the F3 and Fb will all stay the same? Having a 22.5 inch long port is going to take up too much space in my trunk.