DROPPED GUITAR TUNINGS
Dropped Guitar Tunings lower the sixth string, dropping the lowest E string of the standard tuning. Some drop tunings also lower the fifth string (A note in standard tuning). A drop one tuning lowers the pitch by one full step. Some of these may require a baritone guitar due to the string tension required for extremely low notes. Others can be achieved using a capo and/or a partial capo.
What matters for the purposes of fingering is the relative relationship among the strings. For example, a dropped B tuning has all strings tuned to different notes than a standard tuning, but the strings have the same relationship to each other as a drop D tuning (where only the 6th string differs from standard tuning), and as a result the fingerings are nearly the same as for standard tuning.
Many of the terms below are ambiguous in whether only the 6th string is tuned down (a “drop N” tuning in the standard key of E), or all strings are tuned down, with the 6th tuned down more than the others (usually a “drop 1” tuning in some other key).
For example, a “drop C tuning” usually refers to a “drop 1” tuning in the key of D, i.e. the 6th string is tuned down two whole steps and all others down one whole step. This is equivalent to a standard drop D tuning with all strings turned down a whole step. However, another “drop C tuning” is a “drop 2” tuning in the key of E, i.e. the 6th string is tuned down two whole steps and the others left alone. The former uses standard drop D fingerings, like all “drop 1” tunings, while the latter requires its own fingerings because of the different relative relationship of the 6th string to the others.
Other variant drop tunings tune two different strings differently. Tuning both the 1st and 6th strings down the same amount is common enough to warrant its own name (see “double-dropped tunings” below). However, there are other possibilities.
For example, the Foo Fighters song “Stacked Actors” uses a tuning AADGBE with the 6th string retuned to form an octave on A. This involves dropping the 6th string down a perfect fifth. This is sometimes called a “dropped A” tuning because the lowest string is tuned down to A; but it is different from either the “dropped A” variant of drop D (drop 1 in the key of B) or the less common “dropped A” used by Black Label Society, Mastodon and Periphery (drop a 4th in the key of D).