String Quartet No. 6

The String Quartet No. 6 in B-flat major, Op. 18, No. 6, was written between 1798 and 1800 by Ludwig van Beethoven and published in 1801, and dedicated to Joseph Franz von Lobkowitz.

The quartet is in four movements:

The first movement is in sonata form. The first theme starts in B♭ with a conversation between the first violin and the cello. After a while the second violin takes over the conversation from the cello. It then modulates to the dominant of F major and then F minor for the second theme at around m. 45. After a repeat of the first and second themes, the development section starts in F major. It starts by focusing on the "turn" figure of the first theme. It then shifts to D major and on to G minor and eventually returns to F major before shifting to B♭ for the recapitulation. This time around the second theme stays in B♭. The movement ends without a coda.

The second movement is in E♭ major and starts with the first violin playing a lyrical melody in 4 time. The mood shifts with the move to a minor key and unexpected accents and silences. The viola and cello interject with an odd motif marked "queste note ben marcate".

The Scherzo returns to B♭ major and is a "tour de force of syncopation" and "an explosion of rhythmic eccentricity". "It depends on rhythmic effects of 3 x 2 as against 2 x 3 within the 6 eight-notes to the bar in a moderate 3/4 meter."

The fourth movement is the crux of the piece and possibly the highlight of Op. 18. It is marked "Questo pezzo si deve trattare colla più gran delicatezza" ("This piece is to be played with the greatest delicacy".). The first section, in 4 time is marked Adagio and on one reading matches the "Melancholy" of the title. The second section marked "Allegretto quasi allegro" is in 8 time and is more sanguine. It is a fast and simple evocation of a Viennese ballroom or German country dance. This proceeds in contrast to the first section but eventually grinds to a halt on a fortissimo diminished chord. There follows a brief return of section 1 (10 bars) followed by a briefer return of section 2 (5 bars) (in a minor) followed by an ever briefer return of section 1 (only 2 bars). This is followed by section 3, which is really a lengthier return of section 2, which starts in G and moves back to B♭.