I've been playing a Schilke 13a4a for more than 20 years now and really like it. It's takes some work but I can get a decent "orchestral" sound out of it even though it's not as fat a sound as I would like. What I really like about it is the way it lets me "sizzle" in the upper register. Probably 80% of my playing now is in the upper register so having that sound is very important to me. Lately though I've been working on some more mainstream stuff and the Schilke just isn't cutting the mustard there. I pulled an old Purviance 10 out of a drawer, one that was given to me by a dear friend more than 20 years ago. I really like the way it opens up in the lower register and gives me that big fat sound I'm starting to like now. Unfortunately, when I go back up with it, while the upper register is there, it doesn't have the same sizzle that I can get with the Schilke no matter how hard I try. I'm sure the "sizzle" sound has something to do how focused the air stream is though I don't know for certain. I wonder if the smaller throat and tighter backbore of the Schilke is what gives me that "sizzle" sound. So here's my question, what makes a mpc "sizzle"?