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 commonly added in two different ways. The first and most common method is to increase the width of the fingerboard such that the additional string may be fretted by the left hand. The second method is to leave the fingerboard unchanged such that the extra bass string lies next to the existing bass strings, but free of the fingerboard in the same fashion in which the archlute and theorbo are constructed. Such unfrettable bass strings were historically known as diapasons or bourdons.
Some types of seven-string guitars are specific to certain cultures (i.e. Russian and Brazilian guitars).
In the Renaissance period, the guitar was generally strung with four pairs of strings, termed courses. Each string in a course was tuned to the same pitch. By the baroque period it had five courses and used a variety of tunings, some of the tunings re-entrant. During the eighteenth century six courses became common and the modern practice of using six single strings became the standard practice after 1800. These developments illustrate an ongoing desire on behalf of players to increase the range of the instrument. Seven-string guitars arose from such a desire and have been in use for over 150 years. French guitarist Napoleon Coste (1805–1883) composed works with a seven-string guitar specifically in mind. The Italian guitarist Mario Maccaferri (b 1899) was a celebrated advocate of bass strings (diapasons or bourdons). In Mexico a guitarra séptima or guitarra sétima with fourteen strings, strung in seven double courses has been used for an even longer time and descriptions of it date back to 1776 (Antonio Vargas). This makes the history of the seven-string guitar more than 230 years old.
The Russian guitar, a seven-string acoustic guitar tuned to the Open G tuning, (DGBDGbd), arrived in the beginning of the 19th century in Russia, most probably as a development of the cittern, the kobza and the torban. It is known in Russia as the semistrunnaya gitara (семиструнная гитара) or affectionately as the semistrunka (семиструнка).
Its invention is attributed to Andrei Sychra, who also wrote a method for the guitar, as well as over one thousand compositions, seventy-five of which were republished in the 1840s by Stellovsky, and then again in the 1880s by Gutheil. Some of these were published again in the Soviet Union in 1926.
This type of guitar has been called a 'Russian guitar,' as it has been primarily played in Russia and later the Soviet Union.
The Russian version of the seven-string guitar has been used by professionals, because of its great flexibility and its sound, but has also been popular with amateurs for accompaniment (especially Russian bards) due to the relative simplicity of some basic chords and the ease of playing alternating bass lines.
The Russian guitar is traditionally played without a pick, using fingers for either strumming or picking.
The Brazilian seven-string guitar (Portuguese: violão de sete cordas) is an acoustic guitar used primarily in choro and samba. It was introduced to Brazil in the early 20th century as a steel string guitar. The style of "baixaria" counterpoint and accompaniment technique was developed throughout the 20th century, especially by Dino 7 Cordas and Raphael Rabello. In the early 1980s, guitarist Luiz Otavio Braga had a nylon string version made, and this has become the norm for most contemporary choro musicians such as Yamandu Costa.
The Brazilian seven-string guitar is typically tuned like a classical guitar, but with an additional C below the low E as follows: C-E-A-D-G-b-e; although some musicians tune the C down to a B resulting in B-E-A-D-G-b-e.
In addition to playing choro, seven-string guitarists are utilizing the instrument's extended range to play classical repertoire, often leading to new arrangements of known pieces.
Seven-string electric guitar Ibanez RG7321BK
Semi-Hollow and Hollow Body Electric Guitars
In the United States, the jazz guitarist George Van Eps had a seven-string guitar built for him by Epiphone Guitars in the late 1930s and a signature Gretsch seven-string in the late 60s and early 70s. The Van Eps signature guitar may be the first regular-production seven-string electric guitar. Van Eps tuned his 7th string to A.
Seven-string semi-acousticarchtop guitars were used by jazz-guitarist Ralph Patt after he introduced major-thirds tuning in 1964. Patt's tuning is a regular tuning, in the sense that all of the intervals between its successive open strings are major thirds; in contrast, the standard guitar-tuning has one major-third amid four fourths. Major-thirds tuning has a smaller scope than standard guitar-tuning, and so Patt started using seven-string guitars, which enabled major-thirds tuning to have the E-e' range of the standard tuning. He first experimented with a wide-neck Mango guitar from the 1920s, which he modified to have seven strings in 1963. In 1967 he purchased a seven-string by José Rubio.
The first seven-string guitars were built in the "hollowbody" or "semi-hollow" archtop styles, where the guitar has a central resonating chamber, or a central block with resonant chambers on the sides. This gave the guitar the dark woodiness, breath, and richness that is associated with traditional "jazz" tone, but made it too prone to feedback to be practical for rock guitar playing.
Solid Body Electric Guitars
A solid body seven-string electric guitar was conceived by guitarist Lenny Breau and built by luthier Kirk Sand, debuting at the 1983 NAMM convention featuring a high A-string (rather than the low A-string of Eps). In 1987, Fender signed an agreement with Alex Gregory to produce a Stratocaster-style guitar that featured a high A-string. A small number of prototypes were made. However the unit was never put into production.
The first mass-produced seven-string was the Ibanez UV7 played by Steve Vai and Reb Beach. Vai was drawn to the idea for much of the same reasons seven-string classical and jazz players were—the extended range the additional string offered. After initial experimentation with a high A, a low B was added as the high A proved to be too prone to breaking. (Kirk Sand & Lenny Breau solved the breaking high A string problem by shortening the scale-length to 22.75", Vai's Ibanez is 25.5".) Vai began touring with Whitesnake with a seven-string prototype, and then used the guitars for his 1990 release Passion and Warfare.
The seven-string guitar became prominent when the band Korn featured Ibanez Universe guitars on their 1994 debut album. Like Esp's 7-string, Korn's 7-strings were tuned low, typically a low A. During the 1990s, manufacturers of 7-strings included Fender's subsidiary Squier and Gibson's subsidiary Epiphone.
The trend eventually passed, but many guitarists were introduced to the extended range offered by a seven-string guitar. This was somewhat offset by a growing stigma that a seven-string guitar was a "nu metal" instrument, fit only for heavy riffing. This was ironic as Korn guitarists Munky and Head remember being told in their early days that the seven-string guitar could not be used for riffing, as it was a guitar for technical guitar players.
In the 1990s, several other heavy metal guitarists began using seven-string instruments (notably John Petrucci, Trey Azagthoth, and Erik Rutan), seeing the possibility for detuned riffing while preserving the full upper range of the guitar for solos. However, the seven-string guitar failed to really catch on at this phase in its development, and the Universe model was discontinued briefly in 1995. Historically, Matt Bellamy from Muse used a custom red Manson seven-string to play just one song, "Citizen Erased", with a AADDGBE tuning (the song was originally recorded on a detuned six-string), however has recently started using new Manson custom seven-strings to play new songs "Supremacy", "Survival" and "Liquid State" on his 2012 The 2nd Law album tour. Dino Cazares uses custom seven-string Ibanez guitars; Christian Olde Wolbers has his own signature Jackson seven-string guitar, Jeff Loomis has a signature model made by Schecter and Stephen Carpenter has several of his own models released by ESP. In 2013 Chapman Guitars developed a Strat-type and a Tele-type seven string guitar with the contribution of Keith Merrow. What's new is that the guitar has been designed by Chapman Guitars fans through the "Collaborative Design" method. They ended up being very affordable and high quality when they hit the market in 2014.
The Mexican Guitarra Séptima
There is a guitar of seven courses with double string guitar, totaling 14 strings, known as Guitarra séptima.
Other Seven-String Guitars
In the early 2000s, Roger McGuinn (renowned for his skills on the twelve-string guitar and for his long association with The Byrds) worked with C. F. Martin & Company to develop a seven-string folk guitar. McGuinn's guitar (currently being marketed by Martin) is tuned the same as a standard folk guitar with steel strings, but the third (G) string is augmented with a high octave string. Many of McGuinn's notable guitar solos utilize the G string of the twelve-string guitar to perform the main melody, and therefore the Martin seven-string guitar was designed to achieve this extended range playing without the need for doubling all six of the guitar's strings.
In 2010, Inox Guitars has created a mix of the Brazilian Viola caipira and the Russian semistrunka (семиструнка). This instrument has 2 bass strings (as the 6th and 7th strings of the semistrunka) and five treble courses (as the Viola caipira) and it is used in open tuning (GDGDGBD) as a slide guitar.
The 7-string guitar of today is commonly tuned with a lower B as follows: B1–E2–A2–D3–G3–B3–E4 but other tunings exist. Many jazz musicians tune in dropped A tuning: A1–E2–A2–D3–G3–B3–E4 for improved bass lines. Some players choose a higher tuning and add a high A as follows: E2–A2–D3–G3–B3–E4-A4. Other tunings have also been used for example the Russian guitar is tuned to an Open G chord as follows: D2-G2-B2-D3-G3-B3-D4.
Seven-string electric guitars are used in a variety of musical styles including Classical, Jazz, Rock, Progressive Rock, and Heavy Metal. The Seven-string works well in a band setting, as its lowest note, B1 lines up well with the B0 commonly used for the lowest note of a 5+ string bass. Both the guitar and bass could drop tune as well using a lowest note of A1 and A0 respectively.
Casey, Fred (2003). "From Russia, with strings attached". American Lutherie: The Quarterly Journal of the Guild of American Luthiers (8222 South Park Avenue, Tacoma WA 98408: USA.: The Guild of American Luthiers). Number 75 (Fall). ISSN 1041-7176. Plan number 48, Russian 7-string Guitar. Drawn by Fred Casey and Guild staff. One sheet 24 x 42 inches. Retrieved 9 October 2012.
Griewank, Andreas (1 January 2010), Tuning guitars and reading music in major thirds, Matheon preprints 695, Rosestr. 3a, 12524 Berlin, Germany: DFG research center "MATHEON, Mathematics for key technologies" Berlin, Postscript file and Pdf file
Peterson, Jonathon (2002). "Tuning in thirds: A new approach to playing leads to a new kind of guitar". American Lutherie: The Quarterly Journal of the Guild of American Luthiers (8222 South Park Avenue, Tacoma WA 98408: USA.: The Guild of American Luthiers). Number 72 (Winter): 36–43. ISSN 1041-7176.
Sethares, Bill (2001). "Regular tunings" (pdf). Alternate tuning guide. Madison, Wisconsin: University of Wisconsin; Department of Electrical Engineering. pp. 52–67. Retrieved 19 May 2012.
Sethares, William A. (2011). "Alternate tuning guide". Madison, Wisconsin: University of Wisconsin; Department of Electrical Engineering. Retrieved 19 May 2012.