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b. 24

composition: Op. 28 No. 12, Prelude in G♯ minor

c1 in sources

c1, our alternative suggestion

..

The suggested version based on an A major chord can be considered an acceptable variant. The version was probably the initial one in A; Chopin then changed it to a version that does not sonically diverge from the next two bars. According to us, that change, however, could have been a result of a confusion: b. 24-25 could have been taken for b. 25-26.

category imprint: Interpretations within context; Editorial revisions; Source & stylistic information

issues: Corrections in A , Errors resulting from corrections

b. 24

composition: Op. 28 No. 12, Prelude in G♯ minor

..

In A (→FC,FE) there is not a single  before the a notes (in various octaves). Such oversights of accidentals defining the current key are among the most frequent mistakes of Chopin. The accidentals were added in GE and EE. The same applies to the next three bars. 

category imprint: Interpretations within context; Differences between sources

issues: EE revisions , GE revisions , Omission of current key accidentals , Errors of A , Last key signature sign , Errors repeated in FE

b. 25-27

composition: Op. 28 No. 12, Prelude in G♯ minor

..

As was the case with b. 24, in A (→FC,FE) there is not a single  before the a notes (in various octaves). The accidentals were added in EE (all) and in GE (except a1 in b. 26 and a in b. 27).
See also bars 27-32.

category imprint: Interpretations within context; Differences between sources

issues: EE revisions , GE revisions , Omission of current key accidentals , Errors of A , Last key signature sign , Errors repeated in GE , Errors repeated in FE

b. 26

composition: Op. 28 No. 12, Prelude in G♯ minor

..

In GE the grace note is a g1, which is a patent mistake.

category imprint: Interpretations within context; Differences between sources

issues: Errors in GE

b. 27

composition: Op. 28 No. 12, Prelude in G♯ minor

..

In the main text we add a cautionary  before f1. It was also added in EE.

category imprint: Differences between sources; Editorial revisions

issues: EE revisions