What are “drop” voicings?
A drop voicing is made from dropping one of the tones of a “closed” voicing down an octave (i.e., it’s now the bass note of the chord). A closed voicing is one in which the intervals between the necessary notes are as close as possible. 1-3-5-7 is a good example of a closed voicing. If you drop the second tone from the top an octave, you get a “drop 2” voicing. It’s the same chord, but in a different “inversion” (the root of the chord is not on the bottom) As an example, G C E B is the drop 2 of the closed root position in the key of C. Drop 3 is the same idea but instead drop the third tone from the top of the closed voicing down an octave. Here are some tabs: Cmaj7 chord in root postition: 8x998x. Cmaj7 drop 3: 7x555x.
