A major contributor to the tonal quality, strength, and of course price of an acoustic guitar is it's construction. This diagram illustrates the internal parts of a high quality acoustic guitar. Note that because it takes a great deal of time and skill to brace an acoustic guitar this way, some less expensive beginner guitars are not made this way.

Guitar bracing serves two functions, it strengthens the guitar, and it will "color" the tone. High quality acoustic guitars primarily use high density spruce, with the grain aligned vertically. The high strength to weight ratio means that the braces can be "scalloped", or lightened. The lighter weight scalloped braces allow the soundboard to vibrate more freely, which gives the guitar a fuller, warmer, more resonant tone, but it can give up some "headroom", clarity at high volume.

Definitions of the Guitar's Interior Parts

X-Brace: This is the main brace which forms an X pattern just below the sound hole. The degree of the X shape contributes to the balance between treble and bass tones, a lesser degree raises the treble, and a wider splay increases the bass.

Soundhole: The sound hole's size also contributes to the tone. The larger the sound hole the more treble.

Neck Block: Sometimes called the top block. This is where the neck fits into, either by tenons or screws.

Tail Block: sometimes called the bottom block. The main purpose is for strength at the bottom of the guitar, and for tail pin support.

Lining: The lining's main purpose is to widen the gluing area for the attachment of the soundboard and the back to the sides. Most lining has many small saw cuts to facilitate bending and is called kerfed lining.

Tone Bars: They strengthen the lower section of the guitar body (lower bout), and to balance the treble and bass tones.

Treble Braces: These strengthen the top and increase the treble.

Cross Strut: The cross strut strengthens the top under the fretboard. It's thick due to the high tension the neck exerts on the top in this area.

Soundboard: This is the main vibrating plate of an acoustic guitar, and produces most of the sound.

Bridge Plate: This strengthens the area under the bridge, and provides a hard surface so the ball ends of the strings don't wear through the relatively soft top.

Side Bracing: These can be found on small shop guitars. They add stregthe to the sides and can enhance tone.