Hey there, doing the MTM I think I might have been guided to play even more in the red because of the mmmm-aaa-ooohh.
I recently tried a bobby shew lead mouthpiece and my range got cut off at about E-F on the top of the staff. I think my top lip was going into the mouthpiece and touching the bottom of the cup stopping the vibration. I don’t have big lips, just about average. Reading some material online it seems my problem is either too much pressure or that I am pushing my lips too much forwards.
I went to a private teacher, he thought there was not much wrong with my embouchure or how I playing but he suggested that I should try to hide the red of my lips when setting up the embouchure and keeping the embouchure firm. Doing that, my range drastically improved while doing range exercises but it felt strange and I have not been able to combine it with my other playing. And yes another problem, sometimes there is just no sound and no vibration.
Doing this approach for roughly a month, my cheeks feel tired all the time, even if I rest for a day. I have heard that most professionals don’t even use the muscles in the cheeks, see pops tensionless playing.
Maybe I should try to:
a) play with less red, slightly curling the lips inwards
b) try to relax more, especially in the cheeks and try to focus on the embouchure corners and the chin.
c) spend some time with limited range and NO HARD WORK, training my brain that playing should be easy.