Minecraft wiki entry for Note_Block, associated text: The string bass and didgeridoo are two octaves (24 semitones) lower than the standard range, the guitar is one octave (12 semitones) lower than the standard range, the flute is one octave above the standard range, and the bells, chimes, and xylophone are 2 octaves above the standard range. This gives the player six octaves (72 semitones) of effective range to combine instruments for greater pitch coverage.