C# Dominant 13th (C#13)
Also written as Db Dominant 13th (Db and C# are the same key).
Notes in C# Dominant 13th
Inversions
Same notes as C# Dominant 13th, with a different chord tone as the lowest note. Useful for smoother movement between chords instead of jumping around the keyboard.
Root position
C# in the bass
1st inversion
E# in the bass
2nd inversion
G# in the bass
3rd inversion
B in the bass
4th inversion
D# in the bass
5th inversion
F# in the bass
6th inversion
A# in the bass
Open voicings
A close-position chord like C# Dominant 13th can sound cluttered in the middle of the keyboard. Jazz players open it up by dropping one note down an octave, spreading the same notes wider without changing the chord.
Drop 2
C# on the bottom
Drop 3
C# on the bottom
Play C#, E#, G#, B, D#, F# and A# together and you get C# Dominant 13th.
The fullest dominant chord on the page, stacking every odd-numbered extension on top of a plain dominant seventh. Playing all seven notes at once gets muddy fast, so most pianists quietly drop the ninth and eleventh and voice just the root, third, seventh and thirteenth.