I made a box for 2 new Kicker L7 12", what would the tuning be? The outside dimensions of the box is 15"hx30.5"wx27"d. It has one sloted port that has the inside dimensions of the port is 13.5"x5.5"x14.5"long. The port and box is made out of 3/4" mdf, the port is between the 2 subs on the same side. Would it be 38Hz or am I out to lunch?