Bach 2C vs Kelly 7C
The Kelly 7C has a wider cup diameter.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 2C
• Cornet
Cup diameter16.50 mm / 0.6496 in
Best suited for
All-round versatile — balanced cup for general playing
vs
Mouthpiece B
Kelly 7C
• Cornet
GeneralCup diameter16.51 mm / 0.6500 in
Best suited for
All-round versatile — balanced cup for general playing
Beginner / intermediate
Cup Diameter
The Kelly 7C has a cup diameter of 16.51 mm / 0.6500 in compared to 16.50 mm / 0.6496 in on the Bach 2C — a difference of 0.01 mm / 0.0004 in. A wider cup generally produces a fuller, darker tone but requires more air support.
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.