Ein Ais-Septakkord (5. Stufe zu Dis-Dur, 9 Kreuze) ist mir auch schon bei Debussy untergekommen.
"...
Note: Key signatures of
up to one triple-flat + six double-flats = 15 normal flats (!) appear in Dumitrescu (2007), pp. 141-170. However, it's not clear that this qualifies as CMN. (contributed by Hook, who comments: "This is a modern realization of a 16th-century motet. The original manuscript was written in a circle. The author doing the reconstruction argues that the proper way to perform it requires adding flats at each repetition, and this is where that brings us by the third page.")
..."
pitch, 3b
Wüde ich aber eher der Abteilung 'pathologisch' zuordnen wollen.
Grüße
Häretiker