Okay, I about ready to jump into DIY subwoofer building. I have built a sealed car sub before and have the building techniques down. The design is what I would like help with. I am looking for home theater bass to add to my existing set-up. I have a Yamaha RX-V800 (100w x 5) and Klipsch Forte II (L&R) FR: 32Hz-20kHz +/- 3dB Sen: 99dB. With a 12” woofer and 15” radiator, they produce pretty good bass but I need better for home theater. This set-up is in a finished basement. The room is approximately 10’ x 20’. My Yamaha cut-off for the sub is 90 Hz. I have an Adcom GFA-545II amp (100w X 2 into 8 ohms) that I would like to use for the subwoofer. I was looking into the Adire Shiva 12” and using a ported design. I could then wire each voice coil to one channel. I was thinking of using a Sonotube design. After using the LspCAD, I was planning on a 160 liter cabinet with two 3” dia. x 10.3” long ports. This seams to get me a pretty flat response to just about 20 Hz. Does anyone have recommendations for me? Also are there any companies where I can buy an enclosure without the amp (or cut-out)?