String Duo No. 1 (Mozart)

Wolfgang Amadeus Mozart's String Duo No. 1 in G major for violin and viola, K. 423, was written in 1783. It was the first of two duos that Mozart wrote to complete Michael Haydn's set of six for the Archbishop Colloredo.

Background
The String Duo No. 1 in G major for violin and viola, K. 423 was the first of two duos that Wolfgang Amadeus Mozart wrote to complete Michael Haydn's set of six for the Archbishop Colloredo.

Description
It was written in the summer of 1783. It is in three movements:


 * 1) Allegro, common time
 * 2) Adagio, C major, 3/4
 * 3) Rondeau: Allegro, cut time

Whilst the duos by both Mozart and Haydn give the viola many double stops, Mozart's duos differ in that the viola also gets many passages in semiquavers (sixteenth notes), almost in equal proportion to the violin. The American musicologist H. C. Robbins Landon noted of the duo that Mozart used the knowledge he gained in writing his String Quartet in G major, K. 387, the finale of which was in turn influenced by Haydn's Symphony No. 23.

The set of six duos was presented as having all been composed by Haydn, and Colloredo was unable to "detect in them Mozart's obvious workmanship".

By transposing the viola part down an octave, and replacing the viola part's alto clef to the bass clef, the piece is readily playable by a cellist. In 2012, the Austrian composer Gerhard Präsent made an arrangement for string trio (two violins and violoncello), which has been performed several times by the ALEA Ensemble.

The duo is almost always paired with the String Duo No. 2, K. 424. The Hungaroton label has a 2-CD set of the Mozart and Haydn duos with Barnabas Kelemen and Katalin Kokas. The Avie label prefers to put Mozart's duos (played by Phillipe Graffin and Nobuko Imai) on a 2-CD set with other pieces by Mozart, such as the Violin Concerto in G, K. 216, and the Sinfonia Concertante in E-flat major, K. 364. The Odeum Guitar Duo has recorded a transcription of K. 423 for two guitars.