From Mojobari:
http://www.mojomouthpiecework.com/FAQ/tabid/55/Default.aspx
Q. What are the differences between a Selmer C*, C**, D and E? (
tip opening FAQ)
A. This basic question should be visited more often. In the case of Selmers, these letters and asterisks designate tip opening sizes. That is, the distance between the tip of the reed and the tip of the mouthpiece when the reed is at rest. When you stay with a basic mouthpiece design and go gradually larger with the tip opening, it takes more air to get the reed to vibrate. Some call this "more resistant" since it is harder to get the sound going. I prefer that it is "less responsive" in generating sound and "less resistant" to air flow since you now use more air when playing.
But the key to playing larger tip openings is to match them to softer reeds. This recovers the responsiveness and can actually be more responsive than a hard reed with a close tip opening.
I think a larger tip with a softer reed is easier to play at both ends of the sax range. On a close tip, your embouchure eventually gets strong enough that the reed closes off when you play loud on high notes. This causes you to use a harder reed. This often makes the low notes difficult to play softly and with control. There are usually leaks in the sax that contribute to this problem. We've all heard players who honk on the low notes. Going to a larger tip and a softer reed often recovers the low note response and the set-up will not close off on the loud high notes.
Now the problem with going too large is pitch control. Larger tips are "more expressive" in that a good player can bend the pitch and shade the tone easier. But the intonation now changes more with subtle embouchure moves. Even highly experienced players will get to a point where going larger in tip opening is not a good thing.
Lastly, let's talk tone. To me this is a secondary consideration when going to larger tips. But once you get into a comfortable zone of tip openings and reeds, you can try neighboring sizes for fine tuning tone and response. You can also try different mouthpiece designs to assist in getting the sound you want. Anyhow, the general change in tone, as one goes larger in tip opening and softer in reed strength, is to get a darker and louder sound. To compensate for this effect, most open tip mouthpieces in use have a baffle added to the design to add brightness to the sound.
So how much change in tip opening should you try? On tenor and bari, a .010" larger tip opening will feel like a "step." You will most likely need to drop down 1/2 reed strength. A .005" change will feel like a 1/2 step and might help in zeroing in on a good size. Some players can adjust to a leap of 2 steps, but 3 is not recommended.
On alto and soprano, a step is more like .005" in tip opening. You can argue that maybe soprano should be .004" and alto .006" or so, but you get the idea. If you study a mouthpiece chart of tip openings you will see that most makers increment their sizes in the steps I listed and many offer 1/2 steps.
