Hello everyone,
I've been playing the french horn for five years now, and I absolutely love it. The problem is I cannot really play in the high register. The thing is I practice a lot (daily), but I still can not play high notes. I can play up to a high F (fifth line on the treble clef) when doing scales or chromatic tones, and it sounds great and the sound is really stable (sometimes I can go even higher). But when playing a piece, air starts to leak out even with a high C. My teacher says it might be my mouthpiece. My lips are really big (27mm/1,06 inches aprox, I'm half black). I used to use a Schilke 32 mouthpiece, and then my teacher gave me another one with the same diameter but with a shallower cup, which really helped me at first. My ressistance is a bit weak too, because of the huge effort it takes to play the high notes. Do you have any tips? I really need to get better, because I was planning to study professionally next year.

So I'm trying to picture this. Is your mouthpiece so small it doesn't even cover your lips? I think that is what you said. I suspect you just aren't getting support from the mouthpiece so when you try to go high, you suffer a blowout.

Standard things to blow higher are shallower cup, smaller throat and even a small bore horn but if you are playing all the time and still stuck on F, I'm not sure any of those are really going to make the difference.

A lot of manufacturers take their widest mouthpieces and really open up the bore and deepen the cup which is the wrong combination for what you want to do.

I think you can get a Laskey 85J which would be 18.5 mm and shallow cup that's the widest one I know that you can get shallow cup. I'd really think that might help you. You might even end up needing a custom mouthpiece.

Thank you so much for replying, I strongly feel that the custom mouthpiece is the best option. Thanks for the advice.