Watch the Drop 3, 4 Voicings: online guitar lesson by Brad Carlton from Guitar Lab: The Golden Arp
The drop 3, 4 voicing of the Add 9 chord in 1st inversion is derived from the 1st inversion close voicing. As with the root position forms, be sensitive to potential intonation problems. Apply fingerpicking or hybrid picking because of the unused string between voices 2 and 3. Remember that any of the 1st inversion Add 9 voices have the 9 (2) as the lowest voice (voice 4). Because of this, be sure to play these voicings over a root in the bass to hear the total sonority.