I am about to build a box for a 2245H sub. I am using the 1983 article: http://www.lansingheritage.org/html/.../1983-subs.htm

I am going to build the 12 cu ft - 25 hz unassisted box. If I read the article right, the port will be 9 inches? Is this correct? If it is correct it will be 20 inches in lenght.

I am not able to find any 9 inch PVC. I can find 6 inch, so can anyone tell me what the equivilant for a 9 inch x 20 inch port be if I use 2 - 6 inch ports? What would be the length of each of the 6 inch ports?

Any reliable help would be greatly appreciated.

Thanks
Scott