Watch the Drop 4 Voicings online guitar lesson by Brad Carlton from Guitar Lab: The Golden Arp

The drop 4 voicings are quite easy to see on the fingerboard as all you're doing is dropping the fourth voice of the close voiced forms down one octave. This fattens up the chord and sometimes makes the fingering a little more user-friendly compared to the huge stretches involved in the close voiced forms. The video will demonstrate all fingering options for this inversion of the drop 4 add 9 chord.