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
Guitar tunings tuning and typically lowers the pitch ("drops") of only a single string, more common is the whole instrument and least common is two dropped strings (ie. DADGAD). This is almost always the lowest pitched (E) string on the guitar, although occasionally the A string may be lowered. The Drop D tuning, for example, is common in classical guitar and heavy metal music. For it, the low E string is tuned down one whole step, to a low D, and the rest of the guitar remains in standard tuning. This creates an 'open power chord' (three-note fifth) with the low three