Bracing

The internal struts glued under an acoustic guitar's top or back, which stiffen the plate and shape how it moves.

Bracing is the great compromise in acoustic design: the plate must be light and flexible enough to be driven by the strings, and stiff enough to hold up under their tension without bellying or cracking. A pattern like X-bracing gives strength across the width of the top, while scalloped or shifted patterns remove material to free up the low end at the cost of some headroom. Voicing an instrument is largely the business of shaving and shaping these struts.

Example: two dreadnoughts of the same woods can differ noticeably in bass response purely because one has taller, unshaved X-braces and the other scalloped ones.

Bracing

See also