The Mixolydian mode on guitar
The dominant-7 scale: the major scale with a ♭7, and how to switch it chord by chord over a blues.
- Notes
- A · B · C♯ · D · E · F♯ · G
- Formula
- 1 · 2 · 3 · 4 · 5 · 6 · ♭7
- Notes in the scale
- 7
Mixolydian is the major scale with a flattened 7th, and it is the scale that matches a dominant 7 chord exactly — the same 1, 3, 5, ♭7 the chord is built from, plus the notes in between. If you have ever wondered why the major scale sounds slightly wrong over a blues, it is because the natural 7th is fighting the ♭7 in the chord.
The technique worth learning is switching it per chord rather than per key. Over a blues in A, play A Mixolydian on the A7, D Mixolydian on the D7, and E Mixolydian on the E7. Each one lands the chord's own major 3rd, which is the note that makes the change audible to a listener.
That is harder than staying in one minor pentatonic shape all the way through, and it is also the single biggest step from playing over a blues to playing the changes.
Where it sits on the neck
The most useful way to see A Mixolydian is as box 1 with three dots moved and one added.
Every C in the pentatonic shape goes, because Mixolydian has a major 3rd and no ♭3. On the low E and the high e the C at the 8th fret becomes a B at the 7th. On the G string the C at the 5th becomes the C♯ at the 6th, which is the note that makes the whole thing major. Then one dot appears that was not there: the F♯ at the 7th fret of the B string. Three moves and an addition, and the shape you have played since week one is A Mixolydian.
- Root on the A string — the open strings to the 3rd fret.
- Root on the G string — the 2nd fret to the 5th.
- Root on the low E string — the 5th fret to the 8th.
- Root on the D string — the 7th fret to the 10th.
- Root on the B string — the 10th fret to the 13th.
What to play it over
An A7, exactly. After that, the other two chords of the blues, if you are willing to move with them.
The arithmetic is far friendlier than it sounds, because the three Mixolydian scales of a blues in A differ from one another by a single note. A Mixolydian has a C♯; D Mixolydian has a C in its place and every other note is identical. A Mixolydian has a G; E Mixolydian has a G♯ instead and every other note is identical. That is the entire difference.
On the neck it is one finger. Going to the IV, the C♯ at the 6th fret of the G string drops back to the 5th. Going to the V, the G at the 5th fret of the D string moves up to the 6th. One fret, at the moment the chord lands. That is what playing the changes actually is, and it is a great deal less work than the theory makes it sound.
The common mistake
Learning three shapes instead of one. A player hears that each chord wants its own scale and goes away to memorise two more fingerings, then cannot use any of them, because the hand has to relocate at the bar line and there is no time. Stay where you are. Every note you need for all three chords is inside the same four frets, and the change is a finger moving one fret rather than a position moving five. If switching scales is costing you your phrasing, you are moving your arm when you should be moving one finger.