Kelly 7C-UK vs Marcinkiewicz 10
The Marcinkiewicz 10 has a wider cup diameter, the Marcinkiewicz 10 features a deeper cup, the Marcinkiewicz 10 has a larger throat opening.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Kelly 7C-UK
• Cornet
GeneralCup diameter16.51 mm / 0.6500 in
Best suited for
All-round versatile — balanced cup for general playing
Comfortable music-industry standard
vs
Mouthpiece B
Marcinkiewicz 10
• Cornet
Cup diameter16.84 mm / 0.6630 in
Best suited for
Orchestral playing — large cup for full, dark tone
Cup Diameter
The Marcinkiewicz 10 has a cup diameter of 16.84 mm / 0.6630 in compared to 16.51 mm / 0.6500 in on the Kelly 7C-UK — a difference of 0.33 mm / 0.0130 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.