While the six string guitar has been more or less the standard instrument since the mid-19th century, guitarists and luthiers have experimented with additional strings to extend the range of the instrument practically since the emergence of the modern guitar form, sometime in the 15th century. Seven, eight, nine, ten and more strings have been used by guitarists seeking to increase the range of pitches available from the instrument. Some of these guitars are ethnic instruments, specific to different cultures such as Russian and Brazilian guitars. During the 90's the seven-string guitar became popular among metal bands such who used the additional string for extra low end. Extended range classical guitars (especially 8- and 10-string instruments) are being seen more frequently and have foun