Dominant 7 arpeggios on guitar
Root, 3rd, 5th and ♭7 — the four notes of a 7th chord, and why the 3rd is the one to aim at.
- Notes
- A · C♯ · E · G
- Formula
- 1 · 3 · 5 · ♭7
- Notes in the scale
- 4
A dominant 7 arpeggio is the major triad plus a ♭7: four notes that spell the chord exactly. Over a blues, where every chord is usually a 7th, these are the notes that make a line sound like it is following the changes rather than floating above them.
The 3rd is the note that does the work. It is what separates the chord from a minor chord and from the key's minor pentatonic, so landing on it as the chord arrives is the clearest way to signal that you heard the change. Over an A7 that note is C♯; over the D7 it is F♯; over the E7 it is G♯.
A good drill: play the 12-bar form and hit only the 3rd of each chord, right as it lands. Nothing else. It sounds sparse and it teaches your ear where the changes are faster than anything else.
Where it sits on the neck
Almost entirely inside box 1, which is the surprise. In the four frets from the 5th to the 8th, the A7 arpeggio appears in eight places, and seven of them are notes you already play as minor pentatonic: the A at the 5th of the low E, the E at the 7th of the A string, the G at the 5th and the A at the 7th of the D string, the E at the 5th and the G at the 8th of the B string, and the A at the 5th of the high e. The eighth is the C♯ at the 6th fret of the G string. One new dot turns box 1 into an A7 arpeggio.
What you leave out matters as much as what you add. Box 1 holds twelve notes in those four frets, and five of them are not in the chord: the C at the 8th of the low E, the D at the 5th of the A string, the C at the 5th and the D at the 7th of the G string, and the C at the 8th of the high e. Stepping over those five is what makes a line sound like it is spelling a chord rather than running a scale.
- 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, and nothing else. That restriction is the point of an arpeggio rather than a limitation of it.
A blues in A has three of them: A7 is A, C♯, E and G; D7 is D, F♯, A and C; E7 is E, G♯, B and D. Nine distinct notes between them, four of which are outside A minor pentatonic — the three major 3rds and the B in the E7. Those four are the notes a listener can actually hear you choosing.
There is one more thing worth noticing. Each pair of chords shares exactly one note: A7 and D7 share the A, D7 and E7 share the D, A7 and E7 share the E. Those shared notes are where a phrase can cross a bar line without changing, which makes them the easiest places to start playing the changes rather than the hardest.
The common mistake
Learning it as a sweep. Four notes across four strings is a shape that begs to be played fast in one direction, and once that is the only way the hand knows it, the arpeggio can only ever appear as a flourish. A blues does not want a flourish. It wants one right note at the right moment. Take two of the four — the root and the 3rd — and use them inside phrases you already play. An arpeggio you can only perform at speed is a trick; an arpeggio you can enter and leave in the middle of a line is a tool.