Hello again Forum!I'm in need of some design ideas for a hidden sub as part of a system I'm installing inside a small lake house. My wife will not compromise on a floor standing unit as the living area is limited. However, I do have an ideal spot for a sub under the staircase but the grill size would need to be minimal. I can make the cabinet most any size. What sub designs has the group played with that might fit this need? Possibly a bandpass design? Looking for deepest bass extension (playing 80hz and lower) with fairly high SPL capability.The balance of the system will have (4) JBL Control C328C speakers (8" two way coaxial with compression tweeter) in custom enclosures mounted between the rafters and flush with the vaulted ceiling. Powering all of this will be a Crown DCI 8/600N. I will use one channel pair bridged to drive the sub.Any ideas or past designs would be a big help. I will buy whatever JBL driver makes the most sense for this application.Thanks in advance!Mike