hello , friend gave me this box to check is it any good. it uses rcf 15inch speaker for PA duty. it is diy but i dont understand what is purpose of innards. and for my amateur ears it sounds bad,without any bass below 70hz .somehow efficient speaker sounds inefficient in this box. i am thinking of pulling everything out and leaving only regular port at double lenght and without "tooths" ,as it has some sort of ladder or tooth on top side . this is not for any critical listening its just strange so i post here, there is even some sort of schematics glued on inside, but i didnt understand purpose of any of this iregular addons. what should i do? is this some esoteric design or someone gone all artistic with box making.