Watch the i iv: Area 4 online guitar lesson by Brad Carlton from Guitar Lab: CAGED Comping
This lesson covers area four of the A minor to D minor progression. Area four will be in the 12th position on the fingerboard. For the A minor chord you will use the A minor form from the EDCAG system. This chord form is always voiced from low to high as follows: 1 5 1 b3 5. To build the arpeggio for this chord in 12th position you simply need to add the 5 in the 12th fret of the sixth string and the b3 in the 15th fret of the fifth string. All arpeggios are indicated in red in the diagrams. For the D minor chord you will use the D minor form from the EDCAG system. This chord form is voiced from low to high as follows: 1 5 1 b3. To build the arpeggio for this chord simply add the b3 in the 13th fret of the sixth string and the 15th fret of the fourth string then add the 5 in the 12th fret of the fifth string.
Notice that the root of the A minor becomes the 5 of the D minor. Learn this common tone and use it in your rhythm work and soloing. Likewise the 5 of the A minor chord will always move up one half step to the b3 of the D minor chord and the b3 of the A minor chord will always move up one whole step to the root of the D minor chord. Learn these intervallic moves as they will always remain the same no matter what key you are in.
There are two ways to label this progression. The street key would be A minor therefore A minor to D minor would be labeled as a i iv progression in the key of A minor. The theoretical key for this progression is C major: the A minor chord is the vi chord and the D minor is the ii chord. Therefore the respective modes are Aeolian and Dorian. The black numbers on the diagrams add the four notes to the three note minor arpeggios thus creating the appropriate modes.