unknown box design

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.


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I'll bet someone had a bunch of wonderful ideas and the best of intentions. I'd start by putting a little stuffing in and blocking the port and listening to it closed.
Maybe the intentions were the best, but the ideas are very stupid (curved "reflector" with triple coating of Al2O3, SiO2 and CaCO3, and serrated port?!).
PA woofers usually works best in a vented boxes, not in closed.