Dropped A tuning is an alternate tuning for a 7 string guitar where the lowest string is tuned down ("dropped") from the standard B by one whole step to A as follows A1-E2-A2-D3-G3-B3-E4. Also, for a 6 string guitar, dropped A tuning is achieved by tuning all strings down a 4th with the lowest string tuned 1 additional step down as follows A1-E2-A2-D3-F#3-B3. This is a "drop 1" tuning in the key of B (i.e. tune the whole guitar down a perfect fourth from standard tuning, then tune the 6th string a whole step down). As a result, it uses the same fingering as drop D tuning and drop C tuning.
An alternate dropped A tuning utilizes a guitar tuned to E Standard with the 6th string dropped to a low A, resulting in AADGBE with the 6th and 5th strings an octave apart.
Another variation of this tuning is AEADGB, which imitates a 7 on a six-string, excluding the high E.
Another dropped A tuning is AGCFAD ("drop perfect fourth in the key of the D", i.e. whole guitar is tuned down one step, then the lowest string is dropped to A).
Gabe Mangold of Enterprise Earth and Delusions of Grandeur (on Delusions of Grandeur's first two albums Omnipotence and Efficacy before adding a low E seventh string for later Delusions of Grandeur releases and Enterprise Earth releases)
