Seven-string guitar 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
Eight-string guitar and six-string variants. The standard tuning (from low to high) is F#, B, E, A, D, G, B, E. Many prefer to tune the F# to a low E (E1), the same note as the lowest string on a four-string electric bass in standard tuning, and providing the guitar with a fuller sound by having three different E strings. Like the seven-string, the first mass-produced eight-string guitar was made by Ibanez guitars in Japan; the RG2228. The main design issue faced with an eight-string guitar is tuning stability with the lower strings. This is due to the neck being constructed