Watch the I - IV - V Progressions online guitar lesson by Robbie Calvo from Modal Expose
Here's where things get interesting and a little more musical. We now have progressions with three chords in them and they are all major triads. The chords are A - D - E. Those three major triad chords can only exist in one key together and that key would be the key of A major.
I can create a chord progression that resolves to the A chord using all three chords. In that case I would improvise over the progression using the A Ionian mode.
I can also invert those three major triad chords and create a progression that resolves to the D chord. You can hear me play this example and you'll hear that the progression resolves to the D. Does that mean it's in the key of D? No, it's in the key of A with a tonal center of the IV chord, D. So you would play D Lydian over this resolving to tones of the D chord. D-F#-A.
The final step is to invert the progression once more and play E, D, A. Our three chords now resolve and have a tonal center of the V chord, E. You can hear me demonstrate that in the video. Is the new progression now in the key of E? No, it's in the key of A but with a tonal center of the V chord, E. This would then be an E mixolydian progression and you would target tones of E-G# and B.
To recap, a tonal center is where your ear hears the resolution of the progression. We created three different tonal centers using the same three chords from one key.
Let's expand upon that and make each of those progressions a musical jam track and sample solo for you to learn and jam over using each of the three modes.