When I was a student I changed to larger and larger equipment to overcome problems. I confess I had bad sound as well as bad range
To change gear was what I was recomended by my early teachers and in the end I felt I couldn't go larger.
They adviced me to change mouthpiece and also to get a large bore trombone. It did change things, however the real problems I had didn't go away.
For me the larger mouthpieces and larger bore just masked the problems I had. After a honeymoon with a new mouthpiece I just played as bad as before. Not even the change to the Conn 88H helped. It is a real good horn that I still have but as I think now it wasn't right for me at the time.
Things were bad until I finally got a real good teacher and did a complete change of my emboushure. I changed over night from an upstream "smile-embuschure" to a downstream and "pucker-emboushure". I worked hard but it took at least five years to relearn all bad habits and it didn't help I started to study at the Royal Academy of Music, because at such a school you do not work on technique, you work on repertoire.
After I quit the accademy I was fed up on how things were and stopped to play that Conn 88H and also that Denis Wick 6BL I had. I settled on the 6BL because my teacher at the accademy sold it to me and it was considered at least large (not today
). The others who studied there went for Bach 4G's. Instead of he 88h I began to play my old King 3B and returned to the Benge 12C mouthpiece I had when I first started to play. I went back to the tools I had before I started the route of larger and larger equipment.It got easier now to work on technics since I didn't need to play the repertoire anymore. I knew I once and for all had to fix that smile embouschure, because what remained of it wouldn't go away by itself. The old habits were deeply rooted and I got tendencies to return to it as soon as I touched the lower register. When I did I got some terribly disturbing movements in the mouth corners. It worried me a lot and it had to go.
The Benge 12C was educational. It didn't mask my errors. I sounded just as bad as I was, and had to deal with it without help of a larger mouthpiece that only gave me a "woofy" sound. A diffuse sound without any edge that I mistakenly thought would become a solid and sonourous sound just by more practice. In time I did overcome the terrible "smile-emboushure" and today I can not play like that at all. I consider myself repaired.
I've kept the habit to practice my smallest mouthpieces and return to them daily. It''s only if I need a bigger sound or if I need trigger notes that I switch to larger mouthpieces and larger trombones, but next morning I always return to the small equipment, because that's were I feel most comfortable.
/Tom