Its relative minor is F minor. Its parallel minor, A-flat minor, is usually written instead as the enharmonic key of G-sharp minor, since A-flat minor, which contains seven flats, is not normally used. Its enharmonic, G-sharp major, with eight sharps, including the F, has a similar problem, and so A-flat major is often used as the parallel major for G-sharp minor. (The same enharmonic situation also occurs with the keys of D-flat major and C-sharp minor.)
Since A-flat major was rarely chosen as the main key for orchestral works of the 18th century, passages or movements in the key often retained the timpani settings of the preceding movement. For example, Beethoven's Symphony No. 5 has the timpani set to C and G for the first movement. With hand-tuned timpani, there is no time to re-tune the timpani to A-flat and E-flat for the slow second movement in A-flat major; accordingly, the timpani in this movement are reserved for the passages in C major. In Bruckner's Symphony No. 1 in C minor, however, the timpani are re-tuned between the first movement in C minor and the following in A-flat major.
Charles-Marie Widor considered A-flat major to be the second best key for flute music.[1]
A-flat major was the flattest major key to be used as the home key for the keyboard and piano sonatas of Domenico Scarlatti, Joseph Haydn and Ludwig van Beethoven, with each of them using the key for two sonatas: Scarlatti's K. 127 and K. 130, Haydn's Hob XVI 43 and 46, and Beethoven's Op. 26 and Op. 110, while Franz Schubert used it for one piano sonata. It was also the flattest major key to be used for the preludes and fugues in Johann Sebastian Bach's Well-Tempered Clavier, as flatter major keys were notated as their enharmonic equivalents.
^Charles-Marie Widor, Manual of Practical Instrumentation translated by Edward Suddard, revised edition. London: Joseph Williams (1946) Reprinted Mineola, New York: Dover (2005): 11. "No key suits it [the flute] better than D-flat [major]. ... A-flat [major] is likewise an excellent key."
External links
Media related to A-flat major at Wikimedia Commons