The build is underway so it is time to post some pictures. Like all builds this one started by cutting out the parts. I also cut the parts for an N3S center channel while I was at it.
Instead of trying to cut out a bunch of half circles for the Brace B's I decided to cut them out of one long strip. That way I could cut complete circles for most of the openings and leave additional material for the two end openings. That way I had a solid piece of material for the center pin.
I also cut long strips of the proper width for each of the other braces, rounded over a long edge then cut them to length on the miter saw. This way I didn't have to try and round over the edges on small pieces. I forgot to take pictures of this part though.
When I got ready to start cutting out the openings I set up the Router Buddy circle jig
Then I countersunk screw holes in the waste area of the openings to be cut out
This let me secure the pieces to the backer board and, along with clamps on the outside of the piece insured the router would not run out when I cut through a hole.
Next I cut out the openings for the woofers and for the Brace B's. No pictures for the woofer openings, just the brace B's
Then I rounded over the backs of the woofers and both sides of the braces. Again, no pics of the woofers
Then I used a 12" sliding miter saw to cut out the individual brace B's