How to Play Minor Modal Interchanges on the Guitar
On the guitar modal interchanges also take place in songs that have a minor tonic chord. Here are some of the most common minor chord modulations.
How to mix Aeolian with Dorian
Aeolian and Dorian are the two most commonly mixed minor modes. The main difference between them is that Aeolian has a minor iv chord, while Dorian has a major IV chord. One way to mix these modes is to use both types of IV/iv chords in a song.
Fly Like an Eagle by Steve Miller Band uses an interchange similar to the one shown here. The song is in the key of A minor, but you hear both a D major and a D minor chord. Tangerine by Led Zeppelin starts in A Dorian, switches to G major for the chorus, and later changes again to A natural minor for the guitar solo.
Staring at the Sun by U2 uses chords drawn from A natural minor during the verse and C major with a borrowed D chord during the chorus. Ecstasy by Rusted Root mixes D Dorian, D natural minor, and D major.
How to mix minor with harmonic minor
Minor key songs often mix natural minor and Dorian chords with a V7 from harmonic minor.
A perfect example of a song that mixes A minor modes and harmonic minor like shown here is Wild World by Cat Stevens.
The traditional folk song House of the Rising Sun uses another variation of the same interchange, as shown in House of the Rising Sun.
Other songs that mix A minor modes and harmonic minor include Moondance by Van Morrison, and Stairway to Heaven and Babe I’m Gonna Leave You by Led Zeppelin. Straight On by Heart mixes B natural minor, Dorian, and harmonic minor.
Two songs — Smoke on the Water by Deep Purple and Grease from the musical motion picture Grease — have chord changes that mix all three minor modes (Aeolian, Dorian, and Phrygian). Smoke on the Water has the chords Gm and F from G Aeolian, C from G Dorian, and Af from G Phrygian.
Grease has the chords Bm, E, and Fsm7 from B Dorian; Em7, D, C, and Bm from B Phrygian; Em7, and Fsm7 from B Aeolian; and even E7 from B harmonic minor.
With modal interchange, the parent major scale changes, but the tonic pitch remains the same. For example, Crazy on You uses A Aeolian, A Dorian, and A Ionian, each of which is built from a different parent major scale, but the tonic pitch remains A throughout the song.
How to use a minor iv chord in a major key
Another type of chord change is when a minor iv chord is used in a major key. Normally, IV is major in a major key, as in a I-IV-V chord progression. However, many songs put a iv chord in between IV and I to create some kind of chromatic voice leading, as shown here.
In the progression F-Fm-C in C major, the 3rd of the F chord, A, leads to the 3rd of Fm, Af, which in turn moves to the 5th of the C chord, G. You can see the minor iv chord as borrowed from C minor, the parallel minor key.
The Beatles use this minor iv chord change quite a bit. For example, you hear it in Nowhere Man with a iv chord, Am, leading to the I chord of E, and in Across the Universe where iv-I is Gm leading to D (guitars tuned down one half step to Ef).