Bach 6½AL (large shank) vs Kelly 12C
The Bach 6½AL (large shank) has a wider cup diameter, the Bach 6½AL (large shank) features a deeper cup.
Base metal or construction (e.g. brass, stainless steel, plastic). Influences weight, response, and tone color.
Mouthpiece A
Bach 6½AL (large shank)
• Trombone
Material—
Best suited for
Orchestral playing — large cup for full, dark tone
High-volume projection — open throat for power
vs
Mouthpiece B
Kelly 12C
• Trombone
LeadMaterialLexan polycarbonate
Best suited for
Lead trombone; smallest cup
Material
The Bach 6½AL (large shank) is described as unspecified, and the Kelly 12C as Lexan polycarbonate. Material affects mass, warmth, and how quickly the piece responds.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.