The acoustic guitar in all its form has been around for about as long as we have. From simple instruments made from gut and turtle shell to the highly ornamental seventeenth century lute and chittara, our love affair with the most portable and still the most lyrical of all acoustic instruments remains undiminished.
The wood used for body, top and neck of the guitar has an enormous effect on the tone and performance of the instrument. Mahogany has been a traditional material for back and sides as it has strength and tone.
The top of the guitar can be made from spruce, which has a warm sound, maple with a brighter sound or koa wood, which has a similar sound to mahogany but with an enhanced mid-range. Rosewood, alder, poplar, basswood and even bamboo can all be used in the manufacture of a acoustic instruments.
The top of the guitar is usually made of one piece of close grained spruce, split in two and laid in half over the top. This process is called 'bock-matching'. To enhance the appearance of the guitar a rosette may be inlaid around the soundhole or a thin strip of darker wood may sometimes be inlaid along the guitar behind the bridge.
Steel string guitars have non-adjustable bridges fixed to the guitar top. The function of the bridge is to transmit the string vibration to the guitar top, which will vibrate in turn and amplify the sound of the guitar. The bridge is often made of rosewood or ebony and is fitted with a bone or plastic saddle. The acoustic guitar bridge does not compensate for intonation.
Braces or 'ribs', are thin pieces of wood glued to the top and back of the guitar inside the guitar body. The braces add strength to the guitar and, depending on the number and positioning of the ribs, can greatly affect the guitar tone. The steel string guitar uses the traditional 'X' brace pattern, with the centre of the X just below the soundhole.
The acoustic guitar has a hollow body, usually of mahogany. The body has waisted sides and, depending on the model, may also have a cutaway on the lower bout to enable access to the higher frets. Binding is inlaid around the body at the point where the top and back meet the sides of the guitar. The guitar is finished with polyester, polyurethane or nitro-cellulose lacquer depending on model and maker.
Necks are traditionally made of the same wood as the guitar's back and sides. The neck has an adjustable truss rod running from the nut to the heel of the guitar where the body meets the neck. Nylon string acoustic guitars are not subject to as much tension as steel string guitars and so do not require a truss rod. Acoustic guitars are built to the same scale as the electric guitar, but the neck normally meets the body at the 14th fret.
Frets and Fingerboard
The rosewood or ebony fingerboard is laid on top of the neck and is flitted with 20 or 21 frets. As with the electronic guitar, position markers are laid into the fingerboard to aid the guitarist. Dots are also laid into the edge of the fingerboard at the same position.