Banjo A♭7 chord (Double C)A♭ seventh on the 5-string banjo: 0 1 3 4, and 6 more shapes

Frets, string 4 to string 1: 0 1 3 4 (open position)

1. String 4 (C): open, C
2. String 3 (G): 1st fret, index finger, A♭
3. String 2 (C): 3rd fret, ring finger, E♭
4. String 1 (D): 4th fret, little finger, G♭
5. String 5, the short g: open, G, not in the chord

Sounds: C A♭ E♭ G♭  ·  A♭7 is A♭, C, E♭, G♭ (1 · 3 · 5 · ♭7)

The 5th string: the short g rubs against the A♭ and G♭ in this shape, a semitone away: some players let it ring, some skip it.

Double C tuning: gCGCD, the short 5th string first, then strings 4 to 1.