Billy

I am very happy with the cinema center channel. It has no problem filling the 10' between the sl3's. At this time it is in a large cabinet along with 60' TV and all of the electronics.(It's the spousal trade off until the new house and theater is built.) I can only imagine how good it would sound not hindered by being in a box.
There are some pics of the first 2 bass traps I made in Tips & Tricks forum here in the Saloon on 3/5/06. At that point they were not covered with fabric yet.
Good luck with your concrete walls.