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Thelonious 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 A# to G# (descending whole step), G# to F# (descending whole step), F# to F (descending half step), F to E (descending half step), E to D# (descending half step), D# to D (descending half step), D to C# (descending half step), C# to C (descending half step), C to F# (ascending tritone), F# to Cb (ascending tritone), Cb to A# (descending whole step), A# to F (descending perfect fourth), F to C (descending perfect fourth), C to A# (descending whole step), A# to D (ascending major third), D to D# (ascending half step), D# to C# (descending whole step), C# to G (ascending tritone), G to C (ascending perfect fourth). A half-step bass movement creates a strong leading-tone pull that demands resolution. The predominantly stepwise bass motion creates smooth, connected voice leading. When the progression loops, the bass returns from C to A# 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.