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Black Butterfly in A#
Key of A#
A# (Bb) major requires barre chords rooted at fret 1 on the A string or fret 6 on the E string. Despite the barre demands, it is a common key in funk, New Orleans R&B, and brass band music. The open D string can ring as the major third for added color. A# is a intermediate-level key on guitar because the open D string is the major 3rd of Bb, adding a bright color if allowed to ring. Expect to rely on barre chords throughout, which builds hand strength and unlocks the entire fretboard.
Voice Leading
The bass line moves through C to F (ascending perfect fourth), F to A# (ascending perfect fourth), A# to A# (ascending unison), A# to A (descending half step), A to G# (descending half step), G# to G (descending half step), G to C (ascending perfect fourth), C to B (descending half step), B to A# (descending half step), A# to D# (ascending perfect fourth), D# to F# (ascending minor third), F# to B (ascending perfect fourth), B to D (ascending minor third), D to F# (ascending major third), F# to A# (ascending major third), A# to D# (ascending perfect fourth), D# to A# (descending perfect fourth), A# to D (ascending major third), D to G (ascending perfect fourth), G to G (ascending unison), G to D# (descending major third), D# to G (ascending major third), G to E (descending minor third), E to D (descending whole step). A half-step bass movement creates a strong leading-tone pull that demands resolution. The root motion by larger intervals (fourths and fifths) gives each chord change a strong, decisive character. When the progression loops, the bass returns from D to C by whole step.
Scales for Improvisation
A# major pentatonic works because every note is either a chord tone or a safe passing tone — there are no avoid notes. For soloing, this means you can play freely without clashing. Over dominant seventh chords, A# Mixolydian adds the flat seventh for an authentic blues-rock edge.