I have 3 10in subs. I'm going to be making a sealed box for them. I was wondering if each sub should have its seperate airspace or if they should share the airspace.. ex: 3X 1 cubic foot boxes... or: 1X 3 cubic feet?

Well here is some things about a shared chamber and a split chamber. A shared Chamber you save a bit of spaces and price is a bit lower. With a split chamber you don't have to worry about if one woofer dies then the others don't have to try to make up for the extra space (I hope i said that right) and it also gives you a better Structure

I'm going to go with split, each driver will have .69cubes.. another question, the box is only going to be 6 inches deep, will filling with fiber fill or insulation or other sound deadning material help?