Nien wrote:Well, but what can I do to suppress this annoying sound effect? It is a bug or "feature"? It sounds very disturbing if one key is so highlighet.
The L-modes mentioned by lowendtheory are part of the natural sound of a piano, and the louder you play, the more present they are. These modes can vary significantly from one note to another, even between neighbouring notes, this contributes to the charm of the piano. If you listen to some Horowitz recordings, for example:
https://www.youtube.com/watch?v=-JaY0IZEy90, you will hear a bunch of strong L-modes.
If you want to attenuate them you can reduce the velocity curve (for example use the "Moderately fast keyboard" velocity preset - right click in the velocity panel). You can also reduce the high frequencies in the EQ, for example something like Equalizer = [3000, 5000; 0, -6.0] (copy paste [3000, 5000; 0, -6.0] in the EQ panel).