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 An Infinite Regression") á la funk bassist Larry Graham and the double thumping technique pioneered by Victor Wooten — as well as harp-like arpeggios. Ihsahn of the black metal band Emperor began playing seven-string guitar in 1999 and first played eight-string guitar on his 2010 album "After". Rusty Cooley tunes his eight-string guitar like a standard six-string expanded in both directions. This tuning offers both deeper bass tones than a conventional guitar and extended range in the higher register for lead melodies. Guitarist Justin Broadrick of the English industrial metal band Godflesh introduced his eight-string playing on the 2014 Godflesh