Kelly 3C vs Kelly 7C
The Kelly 3C has a wider cup diameter, the Kelly 3C features a deeper cup, the Kelly 3C has a larger throat opening.
The taper behind the throat leading to the shank. Affects projection and tone character.
Mouthpiece A
Kelly 3C
• Cornet
GeneralBackboreL
Best suited for
Orchestral playing — large cup for full, dark tone
High-volume projection — open throat for power
All-purpose mid-range
vs
Mouthpiece B
Kelly 7C
• Cornet
GeneralBackboreS
Best suited for
All-round versatile — balanced cup for general playing
Beginner / intermediate
Which is better?
Both mouthpieces are categorized as "General" — the physical dimensions above will determine which suits your embouchure and playing style better.