I used the ligature pressure plates from two old theowanne mouth pieces that i don’t use any more.
It sounds crazy but, 3 of those pressure plates placed inside the alto bell and it cleans up the tone.It must somehow trap all the extra faint partials present in a pitch from coming out the bell.
I put three pressure plates in the bell of my tenor and the sax sounded more in tune as my yamaha tuner indicated. Overall sound was richer. Thanks for the tip SXPOET
William