G Viennese trichord/Db
The G Viennese trichord chord consists of the G (Perfect unison), Ab (Minor second) and Db (Diminished fifth) notes, with Db as the bass note.

How to play the G Viennese trichord/Db chord
- Play Db as the lowest bass note in the left hand
- Find G (Root) on the piano keyboard
- Add Ab (Minor second) — 1 semitone above G
- Add Db (Diminished fifth) — 6 semitones above G
- Press all 4 notes simultaneously to sound the G Viennese trichord/Db chord