Ultimate Guitar Lesson

X. Key Centers and Harmonic Analysis

Memorize the qualities of the chords of a harmonized major scale.
Imaj7 iim7 iiim7 IVmaj7 V7 vim7 viim7b5
major minor minor major dominant minor minor 7 flat 5
Memorize the qualities of the chords of the harmonized natural minor scale:
im7 iim7b5 bIIImaj7 ivm7 vm7 bVImaj7 bVII7
minor minor 7 flat 5 major minor minor major dominant

The Roman numerals with the qualities added are called functions.

When analyzing a chord progression you try to fit the chords into the above formulae. Since the dominant seventh and minor seventh flat-five chord occur only once in each key, find chords of these types first and try to fit the rest of the chords into that one key. If it works, then you can play over the entire progression using only one scale.

Label the key centers in chord progressions. Write the numerical functions beneath.

D major              
Em7 A7 F#m7 Gmaj7 Em7 Bm7 A7 Dmaj7
iim7 V7 iiim7 IVmaj7 iim7 vim7 V7 Imaj7

The presence of a m7b5 chord nearly always indicates a minor key center.

Eb minor              
Fm7b5 Bb7 Ebm7
iim7b5 V7 im7

The dominant-quality V7 chord above is not strictly diatonic (the diatonic v chord is minor), but is actually more-frequently used than the “real” one. Play Eb harmonic minor (Bb Phrygian Dominant) over the Bb7 chord.

If one or more chords does not fit the scale-harmony formula, then you have non-diatonic chords or a key change, covered in sections XII and XIII.