This is my third year playing sax and I have only recently used the bis key. My bottom side key Bb spring died so I used the bis as a more in tune replacement. However now that the spring is fixed I have no clue what it's for. I only use it now when there's passages that don't utilize the right hand keys so I have a free hand to smack the other tenors for playing too loud. 😉
Anyways what is the Bis key actually for?
Anyways what is the Bis key actually for?