Find the Right Mouthpiece: After experimenting with several mouthpiece options on the descant horn, I ultimately found the best results on my regular double horn mouthpiece, a Houser Standley GS12 cup with a Model “E” rim. While models such as the Moosewood BD and Osmun Haydn cup did offer lots of ease in the high register, they just never felt quite right on my face. For me I think it had something to do with not being able to comfortably fit my lips into the very shallow cups on these models. The Standley isn’t a huge mouthpiece either, but slightly larger than the Moosewood or Osmun. However, I would recommend trying out these models (or something similar like a Schilke 29) on a descant to see what you think.
High E-flat Fingerings on the High F Horn: Yes, the descant horn responds easier in the high range, but (at least for me) intonation can be a bit goofy above the staff using conventional high F fingerings. In addition to using a slightly more covered right hand position, I’ve also found that using High E-flat horn fingerings on the High F side works quite well for the A-flat, A, and B-flat above the staff. If you don’t have a high E-flat horn fingering chart handy, the new fingerings would be: T1 for A-flat (instead of T23), T2 for A (instead of T12) and T for B-flat (instead of T1). On the horn I’m using (an earlier model Paxman 40M), these alternate fingerings really sound and feel good. Give them a try yourself.
While these and other tips can certainly improve performance on a descant horn, the best “hack” isn’t a hack at all – lots of practice on the instrument. For practice materials I highly recommend two books: Martin Hackleman’s 21 Characteristic Etudes for High Horn Playing, published by Editions Bim, and Dr. John Ericson’s Playing Descant and Triple Horns, published by Horn Notes Edition. In addition to etudes and orchestral excerpts, the latter contains lots of helpful hints for high horn playing, including fingering charts for descant (High F and E-flat) and triple horns.