Reentrant tuning

Reentrant tuning is a tuning of a stringed instrument in which the strings (or the courses) are not arranged in a continuous order from lowest pitch to highest pitch or from highest to lowest. Instead, at least one string is tuned to a pitch that breaks the otherwise ascending or descending sequence; this discontinuity is known as a re-entry.

Most re-entrant tunings contain only one re-entry. For example, in the ukulele the re-entry occurs between the third and fourth strings, whereas in the Venezuelan cuatro it occurs between the first and second strings.

Instruments

Instruments usually tuned in this way include:

Baroque (5-course) guitar

Five-string banjo

Charango

Cittern

Venezuelan Cuatro

Laouto

Lirone

Mexican Guitarrón

Mexican vihuela

Rajão

Sitar

Theorbo

Tonkori

Soprano and concert ukuleles

Tres Cubano/Cuban Tres

Instruments often (but not always) re-entrantly tuned include:

Tenor guitar

Ten string classical guitar

Tenor and Baritone (occasionally) ukuleles

10-bass Gibson Style U Harp guitar

Instruments not usually considered re-entrant, but which have common re-entrant alternate tunings:

Guitar (Nashville tuning and Joe Beck's alto guitar tuning)

Pedal steel guitar (C6 tuning and E9 tuning)

The standard tunings for instruments with multi-string courses, such as the twelve-string guitar, eight-string bass, or Colombian tiple are not considered re-entrant, as the principal strings of each course are ordered from lowest to highest.

Ukulele

Ukuleles other than the tenor and baritone are most commonly tuned in re-entrant fashion; the tenor often is as well, and occasionally the baritone. These conventional re-entrant tunings G4–C4–E4–A4 are sometimes known as high 4th tunings or high G tuning.

Non-re-entrant tunings, also known as low 4th tunings, exist for these instruments.

Charango

The Andean charango, a small 5-course, 10-string guitar frequently made from an armadillo shell, is most usually tuned in re-entrant fashion, with re-entry before and after the octave strung third course.

Other members of the charango family, such as the hualaycho and charangon are usually similarly tuned; the ronroco is often, but not always tuned re-entrantly.