Am building a small vented 10/6 bass cab and have a design question. I apologize in advance if this has already been discussed elsewhere, but I couldn't find it. Eminence's suggested design called for a 3.5" port at a certain length. I already had some 3" PVC, so I did the math to calculate what the same area would be and applied that to two smaller, shorter ports, instead of one longer, bigger one. I have since been listening and not getting the response I expected, so wonder if I was mistaken in my approach. Using WINISD to model the box, whenever I change from 1 vent to 2, the length specified INCREASES instead of decreases, the opposite of what I would expect. Being a horn player, I understand that a longer, bigger pipe equals lower frequencies. Am I getting this wrong, or is the physics of venting counter-intuitive; that longer = higher?