
Soffit Construction
Here are more pictures. This page shows the construction of the soffit, which extends around three sides of the theater room.
Click on an Image to See a Larger Version

Soffit Framing
Perhaps showing my ignorance at framing, each section of the soffit was framed as one piece on the floor. Then each section was lifted in place and screwed to the floor joists and wall studs. The photo shows one of the soffit sections (inside the white oval area) screwed in place.
In hindsight, assembling the soffit piece by piece on the ceiling probably would have been easier, but I was not "smart" enough to do it that way.
Also, in the photo, note that the walls have some insulation installed but not the ceiling (yet). The recessed (incandescent) lighting back cans were installed very early. I did not consider adding additional sound isolation backer boxes at the time, which might have improved sound isolation. At the time, I thought the metal housing of the recessed light would provide enough isolation.
Few, if any, LED ceiling lights were available at the time of this build, so incandescent recessed lights were used.

Side-wall Soffit with Insulation
Here's another picture of the soffit and ceiling. This photo, taken a little later, shows all the fiberglass insulation installed.
The temporarily installed recessed light dangles down. It has a dark bronze finish, keeping with the idea of avoiding light colors throughout the room.

Ceiling and Soffit with Drywall
This photo shows the first layer of drywall installed on the soffit ceiling and walls. The second layer, which has one side covered in green glue, will be added later, but I did not capture a picture of this process.
The wood strip running along the bottom of the soffit creates a tray, which will be used to place rope or strip lighting. This lighting was intended to provide some low-level indirect lighting around the edge of the ceiling. The 2x4 run along the bottom side of the soffit will later have a few molding pieces attached to it.

Soffit Tray
A view from inside the rope light tray that is part of the soffit. The inset image in the upper right shows a similar view with the rope light installed. (Actually, it's just laid down in the tray.)
The design of the soffit and this light tray contains several minor mistakes. The total width of the tray, including the 2x4 and molding, is close to 6 inches, much more comprehensive than it needs to be. The tray is ~3 inches but does not need to be more than 1 inch.
I originally planned to attach the rope lights to the drywall nicely with some brackets that came with the lights, but they did not work well. Having the lights perfectly straight in the tray was unnecessary, so I ended up just laying them down without any attachments.

Corner Painted Grey
In this photo, the soffit construction has been completed, and molding has been attached to the 2x4 and the bottom corner of the soffit. The blue masking tape along the top of the molding was there to prevent paint drips from falling on it.
The next step was to stain and finish the molding. The inset image at the bottom of the photo shows a close-up of the finished molding on the outside of the soffit's tray.