Bach 2½C vs Conn Imp. Precision 3
The Conn Imp. Precision 3 has a wider cup diameter.
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
Conn Imp. Precision 3
• Cornet
GeneralCup diameter16.41 mm / 0.6461 in
Best suited for
All-round versatile — balanced cup for general playing
Most popular model; all-around
Bright quality of tone in all registers
Cup Diameter
The Conn Imp. Precision 3 has a cup diameter of 16.41 mm / 0.6461 in compared to 16.40 mm / 0.6457 in on the Bach 2½C — 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.