I started to learn trumpet 3 years ago but I was unable to do clean A, B and High C. Just before I gave up I took the lessons of Greg. The singing C series helped me to rebuild the way I play. I think I am almost there. Initially my lips were tie and the sound was dirty when I tried shape change. But after practicing for a few months I am able to focus on natural exhale and the lips vibration as instructed. I could play from C to High C softly now. It takes time. The result is wonderful.