These notes are usually not very flat on a Buescher Big B. Even with the stack keys very open, these notes are usually fairly in tune. I wonder if the problem is not something else, maybe mouthpiece.jaumes said:It´s possible raise the intonation in low D and C without using crescents. I´ve
raised low C, B and Bb, but this does not solve the problem.
Buescher Big B alto.