by Lavender_Harmony » 28 Mar 2012 21:54
It's all in the composition. Just about every piano sound out there can be made sad, emotional. It's not in the sound, it's what goes on behind the piano, the chords and melodies you choose, the pacing, the dynamics and the tension you create, and knowing when to release it, lingering chords, clashing harmonies, all those things.
A sad piano melody will undoubtedly be composed in a minor key. Major chords do factor in, but knowing where those are is both down to theory knowledge and experimentation. Even playing a major note over a minor chord, not nessecarily the third, but those kinds of things.