rowuk

Slotting technically is simply the ability of an instrument to "resonate". The stronger the resonance, the more pronounced the slot. In physics we call this variable "Q".

The efficiency of the player/mouthpiece/horn is in fact something that develops with practice. The most efficient horn and mouthpiece does not help if we for instance are not playing on the center of each note. This can easily happen when you switch mouthpieces. Depending on the volume of the mouthpiece and backbore, the pitch could be slightly different than another combination (blow across the tops of different shaped beer bottles, the volume inside determines the pitch for irregular shaped objects, not the physical length). If you compensate for pitch with embouchure, you are not playing "centered" and it seems like you are "driving on wet ice". I'll bet that your tuning pitch changed (or the position of the tuning slide) during that practice session - allowing you to play closer to the resonant center.

This is why we MUST teach our students to be sensitive to pitch and ALWAYS tune carefully in ensembles. We can increase endurance, quality of sound and volume of sound by letting the instrument do more of the work!

__________________
Whenever I feel blue, I start breathing again.