TLine for a Treo 10"SSP 50sqin port 130.8inches long makes this single 10 sound like a 15 or 2 12" S… | Diy subwoofer box, Speaker box design, Subwoofer box design
Down4sound PRO-FAB HD3 | Dual HD 12-Inch KERF Port Subwoofer Enclosure - Showtime Electronics
Port/Vent Box Design Differences | DIYMobileAudio.com Car Stereo Forum
Dual 8" Subwoofer port layouts: is one better than the other? : r/diyaudio