This is a classic must know lick that sounds great when played with dominant 7 type chords. Guaranteed to confer an instant Gypsy sound to your solo. It employs a technique known as sweep picking, where the pick moves in one direction across the strings. The picking is up, down, down, down. The three downstrokes are played as one movement across the strings in a “sweeping” motion. Sweep picking is often used when playing arpeggios to allow smooth picking with less tension and more speed than alternate picking.
The optional theory bit
So, why does it work? The diminished 7 chord is symmetrical in nature, comprising of four notes, each of which is a minor third (three frets) apart. Because we use 12 notes in Western music (the chromatic scale), this divides equally into four chords. The diagram below illustrates the fact that these four chords contain exactly the same notes.
The first chord in the example below is an E7 (E G# B D). The second and third chords are an an E7b9 and an Fdim7, which share the same notes. In this voicing for the E7b9, the root note on the bottom string has been replaced by the b9, which is the note F. Because they share the same notes, we can also think of Fdim7 as being an E7b9 chord with no root. And because the other three diminished chords all share the same notes, they can all be considered an E7b9 with no root. This is why all four of our diminished arpeggios work so well over the E7. The two chords on the second line are E7b9 and Fdim7 voiced on the first four strings.
Because the dim7 chords are symmetrical, each of them could also be G7b9, Bb7b9, C#7b9, which means that our lick will work equally well over any of these chords.