I actually started on this project. I took my wood mantle apart, removed the board that goes across it below the shelf and above the fireplace, then put the shelf up above the fireplace without the board. The mantle shelf is about 12" lower now and it looks great still. I now can hang the TV a foot lower so the viewing angle won't involve strained necks!
My only issue is, I can't find the studs behind the wall (above the fireplace). I went from left to right with stud finder, no luck. Someone suggested today I go up and down as the studs might go across above the fireplace.
Also I have a QUESTION: Anyone know what to use to run the wires through the wall next to a fireplace? I mean do I need a insulated tube to leave in the wall so the wires don't get hot? Do I just leave the bare wires in there? Anyone know?