The scale tone seventh chords are created by stacking the major scale on top of itself in thirds (like a layer cake); for those of you who are familiar with modes another way of explaining this process would be …
Scale tone seventh chords created via modes:
Bottom notes = Ionian;
2nd note from bottom = Phrygian;
3rd note from bottom = Mixo-Lydian;
Top note = Locrian
Here's the process in C major:
Bottom note (Ionian Mode)
C – D – E – F – G – A – B – C
2nd note from bottom (Phrygian Mode)
E – F – G – A – B – C – D – E
3rd note from bottom (Mixo-Lydian Mode)
G – A – B – C – D – E – F – G
Top note (Locrian Mode)
B – C – D – E – F – G – A – B
Overlay these four modal scales and you have the diatonic scale tone seventh chords derived from the C major scale.
The chords created can be thought of as vertical structures named as follows:
1st structure: C Major 7th (C Maj7)
2nd structure: D minor 7th (Dm7)
3rd structure: E minor 7th (Em7)
4th structure: F Major 7th (FMaj7)
5th structure: G Dominant 7th (G7)
6th structure: A minor 7th (Am7)
7th structure: B minor 7th flat 5 also known as B half diminished (Bm7b5)
The eight harmonic structure is the same as the 1st.
The notes contained in each chord are:
C Major 7th (C Maj7) = C – E – G – B
D minor 7th (Dm7) = D – F – A – C
E minor 7th (Em7) = E – G – B – D
F Major 7th (FMaj7) = F – A – C – E
G Dominant 7th (G7) = G – B – D – F
A minor 7th (Am7) = A – C – E – G
B minor 7th flat 5 (Bm7b5) = B – D – F – A
The note sequence of each chord as shown above is called the root position of the chord and whilst this type of voicing is easy to play on the keyboard in most instances a significant finger stretch is required on the guitar.
To enable these scale chords to be more playable on the guitar it is necessary to invert them; in other words we want to alter the vertical sequence of the notes.
One of the ways we could do this is to take the second note from the bottom and place it on top of the chord ie, move the second note from the bottom up one octave.
Root position CMaj7
B (top note)
E (top note)
Inverting the chord does not change it's name: CMaj7 is still CMaj7.