Although there are a huge number of bracing patterns most classical guitars fall into one of two main types: fan bracing and lattice bracing. Simply put, a number of struts, or braces, are glued to the underside of the soundboard, both to strengthen the soundboard and to transmit the vibrations caused by plucking the strings to the different regions of the soundboard.
With fan bracing the sound-transmitting struts are laid out in a ‘fan’ pattern, narrowing in the direction of the sound-hole, and in a lattice braced instrument they are placed in a criss-cross arrangement rather like an old-fashioned lattice window. Half the lattice struts (which are made from balsa wood) are reinforced with carbon-fibre. The soundboard of a lattice-braced instrument is generally made from cedar, while a fan braced soundboard is more often than not made from spruce.
Another important difference between the two methods of construction is that support provided by lattice bracing permits a much thinner soundboard, no more than a millimetre in thickness, compared with about 2.5 to 2.8 mm for fan bracing.
Lattice bracing was developed by Greg Smallman, but has been adopted with excellent results by a great many other luthiers (Roy Courtnall, for example). The exceptionally thin soundboard makes for a significantly louder sound, and other aspects of the design (such as the lattice itself and a heavier and more rounded back) prevent a ‘banjo effect’, in which a loud sound is produced but dies away rapidly. Smallman guitars are used by a number of top-flight performers such as John Williams.
Many luthiers such as José Romanillos (who made several guitars for Julian Bream) continue to use traditional fan bracing, and Opus One Guitars follows this tradition. Fan braced instruments tend to be lighter, and give sufficient volume for most performance situations. They can project a good volume of sound, if not as much as a lattice braced instrument, and in the end it’s a matter of personal taste and preference.