I am about to create a new box for my HDC3 18 (around 6 cubes @ 36 hz) but im having trouble calculating the port length.
External Dimensions are:
40" wide, 21" high, 21" deep
6" wide, 19.5" high

3/4 mdf

Towncar sent me his design and said the port length is 13.25" deep and extends 10" to the right, and DJ agreed and said it was about 6.4 - 6.5 cubes @ 36 but I keep getting a length of 31" when I try to calculate it myself. I figure im just doing something wrong but can someone else double check to port length before I start making a new box.