Watch the Amaj7 - Bmin7 online guitar lesson by Robbie Calvo from Modal Expose
Our first example chord progression starts with two chords, A major 7 and B mimor 7. I can quickly determine which key these two chords come from by knowing what chord occupies which scale degree in any major scale. The only key in which these two chords can exist like this is A major. A major 7th is the I chord and B minor 7 is the II chord. If you don't believe me check the other charts we gave you.
Okay. So we know we are in the key of A major so we can improvise over this progression using that scale. The next thing to determine is to which chord the progression resolves. The best way of doing that is by playing it.
In this example we start the progression with the A major 7 chord for one measure and then the B minor 7 for one measure. When the track ends you'll hear that the progression naturally resolves to the A major 7 chord. That means we have a progression in the key of A major with a tonal center of A as well. This means we can play the A major scale over this progression resolving to tones of the A major 7th chord. A - C# - E - G#.
This is an Ionian progression and has a tonal center of the I chord.