Thanks, Steve.
The top pictured is a Martin top. I just grabbed it because it was the easiest picture I had to explain what I needed.
The reason i asked is because I am building what you'd probably term a "hybrid" instrument. A hollowed out electric guitar body, with an acoustic top. I'll be using an SBT pickup and Fishman Powerjack preamp. I'm trying to get an electric sized instrument(at least in body thickness) that i can plug into an amp or PA and get a decent acoustic type tone out of.
I had originally decided to use two rather heavy, parallel braces, similar to what Taylor uses in their T5 model, but decided that I wanted a bracing scheme more akin to an acoustic. I need to make sure that the top will vibrate enough to let the SBT pickup amplify the tone. Too thick of a top, or too stiff of one, will negate that, I think. I needed to know why before i could do that. I ended up with a sort of cross between the two, which I think(hope) is going to turn out to do what i want it to.
I took the size and shape of a Gibson L-OO, transferred it to a solidbody blank, and hollowed it out.
I moved the bridge and bridge plate forward(toward the neck) to give me a neck joint at the 16th fret, like an electric. That removed the possibility, at least at my current skill level, of an X braced top. So i ended up with a bracing scheme somewhere in between a twin parallel bracing pattern and a more acoustic type. Here's the bracing pattern I ended up with.
The top is approximately .118" thick. Thicker than a standard acoustic, but i think probably needed. The two main braces, and the cross brace in front of the bridge, are 5/16" thick. The two main braces taper from 1/2" tall, down to about 1/8" at the ends. The cross brace is 1/2" tall, and the tone bars I asked you about are 1/4" thick, 1/2" tall at the highest point, and taper to almost nothing. Since the sides are 1/2" thick, I did away with the tone bars you normally see on either side of the bridge. I think the added stiffness of 1/2" sides, as well as the new location of the bridge, will give me plenty of stiffness there without those bars. The two main braces will be glued to the neck block, but nothing else will be notched into the sides. They'll end right before reaching them. I think the 1/2" sides will probably also give me plenty of stiffness without that being necessary, as long as the gap between is not too large.
It's a simple bracing patten, but I think that it will work. If it doesn't, I'll start over until i get it right.
Thanks again for the information/education.