C♯ 6/9 = C♯ · D♯ · F · G♯ · A♯ (root, 9th, 3rd, 5th, 6th/13th). 1320 playable voicings on the standard E9 copedent — the best 12 by neck position below.
Low neck (frets 0–7)
Fret 7 · RKRRKR lowers string 4 a half step (E→D♯); lowers string 5 a half step (B→A♯)Fret 4 · B + RKLB raises strings 3 & 6 a half step (G♯→A)RKL lowers string 2 a half step (D♯→D); lowers string 9 a half step (D→C♯)Fret 7 · LKR + RKRLKR lowers strings 4 & 8 a half step (E→D♯)RKR lowers string 4 a half step (E→D♯); lowers string 5 a half step (B→A♯)Fret 2 · LKR + RKLLKR lowers strings 4 & 8 a half step (E→D♯)RKL lowers string 2 a half step (D♯→D); lowers string 9 a half step (D→C♯)
Mid neck (frets 5–12)
Fret 11 · openFret 9 · RKLRKL lowers string 2 a half step (D♯→D); lowers string 9 a half step (D→C♯)Fret 9 · AA raises strings 5 & 10 a whole step (B→C♯)Fret 9 · CC raises string 4 a whole step (E→F♯); raises string 5 a whole step (B→C♯)
High neck (frets 10–17)
Fret 11 · BB raises strings 3 & 6 a half step (G♯→A)Fret 11 · B + RKLB raises strings 3 & 6 a half step (G♯→A)RKL lowers string 2 a half step (D♯→D); lowers string 9 a half step (D→C♯)Fret 14 · LKR + RKLLKR lowers strings 4 & 8 a half step (E→D♯)RKL lowers string 2 a half step (D♯→D); lowers string 9 a half step (D→C♯)Fret 16 · B + RKLB raises strings 3 & 6 a half step (G♯→A)RKL lowers string 2 a half step (D♯→D); lowers string 9 a half step (D→C♯)