Guitar chords in the key of C# or Db:
Chord Db-5 (4th fret) notes: Db, Abb, Db and F. (Abb is A double sharp or G).
You must leave out the 6th and 1st strings.
Db(C#) major diminished 5th guitar chord's alternative names: DbMb5, Dbmajb5.
1(C#/Db), 3(F), b5(G/Abb).