This horn has beautiful intonation until the A in the middle of the staff, then there is an occasional faint, crackle sound until A above the staff. I am not 100% sure that it was not there before the repair of a hole in the lead pipe right after the mouthpiece receiver with a sleeve. The tech did not replace the entire leadpipe. The sleeve is slightly crooked. I cannot find air leaks anywhere. Other horns do not make the sound when I play.