Hi there, Around 9 months ago, I posted a topic concerning a huge decline in areas of my playing ability, and I'm posting this to review my situation, as much to help myself as others to help me, thanks. Firstly, I do have a very good teacher, who's other students have had huge success, but I only recently started with him. My issue: My tone quality massively decreases from 3rd space C to 4th space E. At the C, my tone is much better than what it was a few months ago, at E, it sounds whiny and out of tune. I think the obvious issue here would is breath support, but I cannot workout why I lack this; I have no issues playing pp or ff, up to C, but upwards from that, with blowing at least as much air through the horn, and trying to maintain the steady airstream that I have below, I still have the issue with the tone. The obvious next step from this (in my opinion), would be excessive contact force/ pressure from the mouthpiece onto the lips, but I again can feel no issues with this below C, and when I go above, I resist the temptation to force it, so I don't think this is the case either. This leads me to believe that it is excessive tension inside the body which creates this issue, eg. the embouchure being too closed, the oral cavity being too constricted by the through, abdominals being too tense and restricting lungs, etc. I'll post my routine, though I don't think that there are any issues with that: Lip Buzzing 2 mins Mouthpiece buzzing 3 mins Long tones 10 mins Lip bends 5 mins Diaphragm attacks 5 mins Lip slurs 5 mins REST Scored pieces 15 mins Improv 15 mins REST Single tonguing 5 mins Double tonguing 5 mins Triple tonguing 5 mins Lip slurs 5 mins Lip trills 5 mins Major scales 5 mins Minor scales 5 mins Arpeggios 5 mins I also play in a 2 brass bands (total 3 hours weekly) a big band (1 hour), and a concert band (1 hour). There're no issues with my equipment. Thanks for the help, I hate to have to waste you good people's time, but I feel that the online community can offer a broader spectrum of opinions and advice than the people I know IRL. Thank you all.