I'm going to try to vent my sub enclosure and I'm using BassBox 6 Pro. I have two Eclipse SW9122's with 3 cubes after displacement and I'm trying to tune to 34Hz. The program suggests 12" x "12 vent 119" long to reach xmax. If I type a vent length of 24" then it changes the other dimension to 6" x 6". I'm not sure if I'm using the program right can someone please help. I've never tried to vent a box before and I want to make sure I do it right.