Hi, I want to get into designing boxes but I've never done it before. I was wondering if someone could design me a box using Torres box calculator for a single 18" Fi BTL N2, tuned to approximately 33 hz. I would like the subwoofer to be facing up, with the port(s) facing back. The main thing is I'm not really sure how to design a port, if someone could provide a detailed explanation on the process of using the calculator to design a box to your desired results that would be great. Because I really am not sure how to decide the shape, number, and length of a port.
Thanks to anyone who is willing to help me with this.
P.S. this is an actual box design that I would make and use, as I'm planning on getting a BTL soon, and it would be going in a trunk.