Hey ! Got a ultra sonic super old and son trumpet for like a year and i got this thing appearing. I don't know if it's corrosion or oxidation. Btw i just wanted to know if it's something that i should be worried or not.
Got the f10 standard version. Rly great playing. sound wise i got the m7 in the past so i know the preamp is the same (i guess) and its sounding great. was not setup well but not terrible. Finishing wise its good but not perfect, was expecting a bit more for a 1700e instrument but its not affecting the playing. fret are great ! im gonna have fun with this new beast in my collection !