Extended-range classical guitar

A classical guitar with additional strings is a nylon-string or gut-string classical guitar with more than six strings, in which the additional strings pass over a fingerboard so that they may be "stopped" or fretted with the fingers. These are also known as extended-range guitars, and should not be confused with harp guitars (in which the added strings do not pass over a fingerboard; see below).

While the invention of the seven-string guitar has sometimes been attributed to Russian guitarist and composer Andrei Sychra, guitar historian Matanya Ophee has found evidence that seven-string classical guitars may have already existed in Europe in the late 18th century, when Sychra was just beginning his career.

There is no question, however, that Sychra was a great proponent of the seven-string instrument, having written a method, and more than one thousand compositions for the instrument. Seventy-five of these pieces were republished in the 1840s by Stellovsky, then again in the 1880s by Gutheil. Some of these were published again in the Soviet Union in 1926.

Sychra's guitar was a nylon-string "classical" variation of the traditional Russian Gypsy Guitar (now usually steel-strung), and tuned in a similar manner, to an open 'G' chord:

The modern seven-string classical guitar is usually tuned the same as the modern standard six-string instrument, with the addition of a low 'B' strring:

As with any guitar, many tuning variations are possible, and not uncommon.

Eight-string classical guitars are generally tuned with two extra basses ([BD]EADGBE) that vary in pitch depending on the piece being played. Another common variation is to add an extra bass and treble string. The extra treble is almost always tuned to A, while the added bass string usually falls on A,B, or C.

Paul Galbraith and Alexander Vynograd are two of the most notable 8 string players who use the extra high and low string tuning. Galbraith generally tunes (B)EADGBEA which puts standard 6 string guitar chord voicings and scale shapes within the neck and allows him to read lute tablature directly (a whole step higher). Vynograd chooses to tune AEADGCEA (notice the b string is tuned up a half step) which allows him to play the top 6 strings like a guitar a 4th higher. Vynograd writes his music on a grand staff in a different key and plays as if the guitar was tuned EBEADGBE.

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Wikipedia