Dan (LOL) I sent Mike Jon Rische's site and another DIY site as well. Your interpretation BTW is incorrect (as far as all the info I've read anyway). "half open" in the context of tube traps , means that half of the exterior curved surface has to be wrapped or covered. And the other half of the surface, the fiberglas is exposed.
If you've ever seen an ASC tube trap, they are marked as to which half is which so the user can orient them as desired -- meaning that if you turn the open side toward the wall, they absorb mostly bass, but little HF. The tube interior should be left open to provide a resonant chamber which dissipates the bass energy (sort of like an organ pope in reverse ;-)
If you've ever seen an ASC tube trap, they are marked as to which half is which so the user can orient them as desired -- meaning that if you turn the open side toward the wall, they absorb mostly bass, but little HF. The tube interior should be left open to provide a resonant chamber which dissipates the bass energy (sort of like an organ pope in reverse ;-)