Capo plays a B note for any capo position at or below the seventh fret), and thus a performer does not need to adjust for or relearn the entire fretboard as they might with retuning. The scale length of the strings of an instrument affects the timbre of the strings, and thus the use of a capo may alter the tone of the instrument. Musicians also use capos to bring a guitar tuned below standard up to standard tuning. Manufacturers sometimes recommend tuning a twelve-string guitar a whole-step or more below standard to offset the additional stress of the additional strings.
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