Twelve-string guitar 12

Twelve-string (12) guitar is an electric guitar or acoustic with 12 strings in 6 courses, which produces a richer, more ringing tone than a standard six-string guitar. Essentially, it is a type of guitar with a natural chorus effect due to the subtle differences in the frequencies produced by each of the two strings on each course.
Twelve-string guitar Chorus effect
The double ranks of strings of the 12-string guitar produce a shimmering chorus effect. To produce this effect individual string sounds with roughly the same timbre and nearly (but never exactly) the same pitch converge and are perceived as one. When the effect is produced successfully, none of the constituent sounds is perceived as being out of tune. Rather, this amalgam of sounds has a rich, shimmering quality which would be absent if the sound came from a single source. The effect is more apparent when listening to sounds that sustain for longer periods of time, such as a long guitar chord.

Design
The strings are placed in courses of two strings each that are usually played together. The two strings in each bass course are normally tuned an octave apart, while each pair of strings in the treble courses are tuned in unison. The tuning of the second string in the third course (G) varies: some players use a unison string while others prefer the distinctive high-pitched, bell-like quality an octave string makes in this position. Some players, either in search of distinctive tone or for ease of playing, will remove some of the doubled strings. For example, removing the higher octave from the three bass courses simplifies playing running bass lines, but keeps the extra treble strings for the full strums.
The tension placed on the instrument by the strings is great, and because of this, 12 string guitars have a reputation for warping after a few years of use. Some twelve-string guitars have non-traditional structural supports to prevent or postpone such a fate, at the expense of appearance and tone. Until recently, twelve-string guitars were nearly universally tuned lower than the traditional EADGBE, to reduce the stresses on the instrument.

The greater number of strings complicates playing, particularly for the plucking (or picking) hand. The gap between the dual-string courses is usually narrower than that between the single-string courses of a conventional six-string guitar, so more precision is required with pick or fingertip when not simply strumming chords. The pairing of thin, easily broken octave strings with larger, stiffer bass strings presents difficulties to the player also, and only a very skilled player can reliably pluck single strings from within a course at any speed (notably the very high octave G string, which is the highest-pitched string on the instrument). Nevertheless, with practice, the twelve-string guitar is not unduly difficult to play. It is, however, generally used in a fairly restricted role which emphasizes its strengths: rich ringing, full-bodied chords, and fast, rippling single plucked notes on the twinned strings. Twelve-string guitars are made in both acoustic and electric form. However, it is the acoustic type that is most common.