The D7 arpeggio is built from the notes D (R), F# (3), A (5), C (♭7). On Haute Gitanerie you can see it across the whole guitar neck: contained position boxes, long diagonal forms, and its parent scale (D Phrygian dominant), with note names in English (C D E) or solfège (Do Ré Mi).
The D7 chord
The D7 chord voicing uses those same notes (D (R), F# (3), A (5), C (♭7)). Switch the fretboard to Chords to see gypsy-jazz voicings for D7, or keep Arpeggio to practise the tones one at a time. Same shape, two ways to hear it.
How to practise the D7 arpeggio
Start with a contained position box near the low strings, then move it up the neck fret by fret, or follow a diagonal form for a two-octave sweep in the manouche style. Every note is labelled with its interval (R, 3, 5, ♭7), so you always know where the root, third, fifth sit.
On a dominant, the ♭9, or the diminished on its 3rd (= a semitone above the root, the 7♭9 without its root), adds the manouche tension and leads up a half-step to the tonic.
