Watch the 4 Notes-Per-String Forms online guitar lesson by Brad Carlton from Guitar Lab: The Golden Arp

Our final inversion of the Add 9 arpeggio is third inversion. Viewing it as a four notes-per-string form as shown in ex. 5 you will see that the open string will always be the 5, the 5th fret will always be the root, the 7th fret will always be the 9(2) and the 9th fret will always be the 3rd.

This form is very useful as the open string is the 5. The 5 is a great pickup note in a melodic line. Also from a technical standpoint, this form is less demanding on your fretting hand than the other three inversions.

I will demonstrate utilizing open drone strings to create textures when playing these 4 notes-per-string Add 9 arpeggios in 3rd inv. For example, if you are playing the arpeggio on the 3rd string, the chord is CAdd 9. You could use the 1st string open as a drone which would be functioning as the 3 of the chord. Be sure to explore this concept on your own.