No. 23, commonly known as Appassionata. It is considered one of the masterpieces of Beethoven’s middle-period piano sonatas. By this time, the range of the piano had expanded significantly (Érard, 68 keys), and Beethoven made excellent use of this in his composition.
However, regarding the octaves in measures 310 and 312 (C) and measures 318 and 320 (E), looking at the surrounding notes, one could speculate that Beethoven actually intended them to be played an octave lower (C and E, respectively). (This is something I learned from my musical advisor.)
Although the piano’s range had expanded considerably by then, it still wasn’t wide enough to reach those lower notes (the lowest note on an Érard at the time was F1). So, as an experiment, I tried playing them an octave lower.
By the way, from Sonata No. 29, the Hammerklavier, the lower register expanded even further, which seems to have been one of the factors that led to the creation of masterpieces. The history of Beethoven's piano sonatas was thus closely intertwined with the evolution of the piano at the time.
Another interesting point is that in the first movement of this piece, the "Fate motif" (that famous Dun-dun-dun-duuun) appears in the left hand in measures 10, 12, and 13. Here, however, it is played softly in pp, almost hidden. (The section enclosed in a box.)
Upon looking into it, I found that this motif is subtly (?) used in various pieces.
Now, Sonata No. 23 is known for its fast tempo and high level of technical difficulty, especially in the third movement. However, in this MIDI sequencing project, I received quite a bit of criticism regarding the delicate sound shaping within the intense passages, which took a considerable amount of time.
I also received a comment from my musical advisor saying, "Let’s take a break and revisit it later. That might lead to better ideas..."
So, for now, let’s start by giving it a listen.
Title: Piano Sonata No.23 in F minor, Op.57
Sound Source: Vienna Synchron Concert D-274
Audio file format: mp3