Today me and my buddy at my house are starting are sub constuction. I am building a sealed 1503 in a 17.5 in cube He is building a sealed stryke SAE 1204 in a 14.5 in cube. My sub is going to have 1.5 thick walls(3/4 in sandwiched together in a type of lock) that will be biscuit joined together and we are using wood glue and sealing it with silicone caulk Questions: 1. Is one 3/4 in square of mdf with a a 12 in circle cut out good enough bracing or should I use 2 or 3 of these. 2. Why do some people have such intricate shapes in thier bracing ( Ex. Thomas W. Ariel Stryke 15) ? Is a square sheet with a circle cut out good enough? Thanks!