i just figured it out. A revelation. I was not playing with enough air pressure and was blowing from the lips. I started tightening my abdominals from way down low and keeping the throat open, ( sighing the air through the throat and lips) the upper register immediately opened up. Where before I had trouble getting to the D in the upper staff I now get to the C above the staff. I let the mouthpiece hold the lips in place, and stopped focusing on embouchure and shape but on releasing air with the abdominal muscles keeping the jaw and throat out of the picture. I blow less hard now and get higher notes. I could never get the higher notes by shape change as I was so focused on embouchure that the aperture closed as I was trying to go higher by changing shape. I could probably get there eventually but the high air pressure and keeping throat open by sighing seems to work for me. Lets see if it still works tomorrow…
Hey there Hans, I am so pleased you have had this revelation. The really interesting thing is it all comes down to perception. What you are feeling to get the results is great but if I was to say to a student “use your abdominal muscles and increase air pressure to play higher” all kinds of negative issues will arise. This is where it is cool that you have been through the SHAPE recognition period and are now ready to let it go and move on (for the time being).
Once you hit another ceiling, learning to recognise SHAPE and using PASSIVE Reduction will again become important.