Schubert and the diminished chord.

With the romantic period, the music becomes more and more chromatic with the use of ambiguous chords.

The diminished chord is one of them.Here Schubert uses the A°7 chord to go from the key of Bb(VI) to the original Dm key.

It can function as

• VII°7 of Bb
• VII°7 of Db
• VII°7 of E
• VII°7 of G
•  

It can transform into F7,Ab7,B7,D7.

Schubert uses the enharmonic spelling of the german augmented 6th and the dominant chord to go through a quasi-chromatic progression:Bb- Cm-Db (C#m)-Dm

In measure, the Ab7 sounds like the dominant of the chromatic mediant bIIIM, but it resolves deceptively into Cm (Im6/4).The presence of the Db in the melody may be a hint that the Ab7 sounds more like V7/bIIIM than the Ger+6 of Cm when it is first heard...

Schubert Death and the Maiden Quartett for Strings

Uploaded by Afik Blitz on 2014-12-20.

https://www.youtube.com/watch?v=9i5D4ZW8O9o&feature=youtu.be&t=50s