A twelve-string guitar (or 12-string guitar) is a steel-string guitar with 12 strings in six courses, which produces a thicker, more ringing tone than a standard six-string guitar. Typically, the strings of the lower four courses are tuned in octaves, with those of the upper two courses tuned in unison. The gap between the strings within each dual-string course is narrow, and the strings of each course are fretted and plucked as a single unit. The neck is wider, to accommodate the extra strings, and is similar to the width of a classical guitar neck. The sound, particularly on acoustic instruments, is fuller and more harmonically resonant than six-string instruments. The twelve string guitar can be played like a 6 string guitar as you still use the same notes, chords and guitar techniques like a standard 6 string guitar but advance techniques might be tough as you need to play or pluck two strings simultaneously.
Structurally, 12-string guitars, especially those built before 1970 (see below), differ from six-string guitars in these ways:
- The headstock is elongated to accommodate 12 tuning machines.
- The added tension of the six additional strings necessitates stronger reinforcement of the neck.
- The body is also reinforced, and built with a stronger structure, to withstand the higher tension.
- The fretting scale is generally shorter to reduce the overall string tension.