7-string guitar

The seven-string guitar adds one additional string, commonly used to extend the bass range (usually a low B) but it can also be used to extend the treble range of the 6 string guitar.

The additional string is added in one of two different ways: by increasing the width of the fingerboard such that the additional string may be fretted by the left hand; or, by leaving the fingerboard unchanged and adding a "floating" bass string. In the latter case, the extra bass string lies next to the existing bass strings, but free of the fingerboard in similar fashion as the archlute and theorbo. Such unfrettable bass strings were historically known as diapasons or bourdons.

Some types of seven-string guitars are specific to certain cultures such as the Russian and Brazilian guitars.

The history of the seven-string guitar stretches back more than 230 years. During the Renaissance period (ca. 1400-1600 CE), the European guitar generally had four courses, each strung with two gut strings, and the pair of strings within each course tuned in unison. By the mid-Baroque period (ca. 1600-1750) it more commonly had five courses (still double-strung) and used a variety of tunings, some of them re-entrant. By the early eighteenth century six double-strung courses had become common.

Up to this point most stringed instruments were strung with gut strings. Around 1800 quality metal-wire strings became widely available. These new strings were more durable, remained in tune better, and—most importantly—produced a louder sound than the traditional gut strings. As use of metal strings became more widely adopted, their greater volume output impelled luthiers to experiment more with single-strung courses on their instruments, and in a relatively short time the modern practice of using six single strings became first common, and then standard.

The changing number of courses in these early guitars may also illustrate an ongoing desire on behalf of players to increase the range of the instrument, a development similar to that gone through by the lute in earlier days. It is likely that all of these factors contributed to the development of the seven-string guitar, which has been around ever since. The seven-string guitar never became as widely accepted in Europe as the six-string instrument, but a number of composers did produce a significant body of work for the seven string. French guitarist Napoleon Coste (1805–1883) composed works with a seven-string guitar specifically in mind. The Italian guitarist Mario Maccaferri (1899-1993) was a celebrated advocate of bass strings (diapasons or bourdons) and also composed for the instrument. By contrast, in Russia the seven-string guitar became widely popular, and entire schools of playing were developed around its use. Despite some brief setbacks in the mid-20th century, during which six-string instruments rose in prominence, the seven-string Russian guitar has remained popular in Russia to this day. In the New World, a guitarra séptima or guitarra sétima—with fourteen strings, strung in seven double courses—has been known in Mexico since at least 1776 (Antonio Vargas). These instruments may still be found in use in Mexico, although the modern six-string instrument has become far more common. Seven-string instruments retain current popularity in parts of South America, notably Brazil, where they became an important instrument in the choro music of the 19th century, which is currently (2015) experiencing a revival.

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Wikipedia