Open G tuning d g b d'>2. </score> is used by the Russian guitar, which has seven strings tuned mostly in triads, in contrast to other guitars, which are tuned mostly in fourths. Dobros use a full six-string tuning with a bottom G: G-B-D-G-B-D, low to high. The two lowest strings are, accordingly, tuned three semitones higher for the lowest string (from E up to G) and two semitones higher for the second-lowest string (from A up to B) while the highest string is tuned two semitones lower (from E down to D), relative to standard tuning. The 5-String Banjo's standard tuning is
String instrument ways to change the pitch of a vibrating string. String instruments are tuned by varying the strings' tension because adjusting length or mass per unit length is impractical. Instruments with a fingerboard are then played by adjusting the length of the vibrating portion of the strings. The following observations all apply to a string that is infinitely flexible (a theoretical assumption, because in practical applications, strings are not infinitely flexible) strung between two fixed supports. Real strings have finite curvature at the bridge and nut, and the bridge, because of its motion, are not exactly nodes of vibration. Hence the