Bach 2½C vs Marcinkiewicz 306
The Marcinkiewicz 306 has a wider cup diameter, the Bach 2½C features a deeper cup, the Marcinkiewicz 306 has a larger throat opening.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 2½C
• Cornet
Cup diameter16.40 mm / 0.6457 in
Best suited for
All-round versatile — balanced cup for general playing
vs
Mouthpiece B
Marcinkiewicz 306
• Cornet
Cup diameter17.20 mm / 0.6772 in
Cup Diameter
The Marcinkiewicz 306 has a cup diameter of 17.20 mm / 0.6772 in compared to 16.40 mm / 0.6457 in on the Bach 2½C — a difference of 0.80 mm / 0.0315 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.