Built some 4430's out of 1 inch particle board, with 2235, 2425, and 2407 for the high freq. Triamping the drivers with a three way ashly electronic xover. I am noticing I have a hot spot around 250 hertz. The cab's are built like tanks, have been designed in a cab software to dimensions as similar to the 1x1.5x2.5 ratio. The back has been reinforced by a 2x4 along the length of the rear panel slightly off center to avoid any like area. The cabs have been insulated as well with typical pink fiberglass insulation along the top, bottom, sides, and rear. The front panel is not insulated. Any suggestions would be appreciated, and feel free to ask for more details if I missed something. I know my dad's 4430 stock from jbl didn't have this issue, so I doubt it's a driver issue..Thanks..