Bach 8½A vs Conn Imp. Precision 4
The Conn Imp. Precision 4 has a wider cup diameter, the Bach 8½A features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 8½A
• Cornet
Cup diameter16.10 mm / 0.6339 in
vs
Mouthpiece B
Conn Imp. Precision 4
• Cornet
GeneralCup diameter16.41 mm / 0.6461 in
Best suited for
All-round versatile — balanced cup for general playing
Players with large full lips; most common surviving example
Bright tone; same as Model 3 with wide rim
Cup Diameter
The Conn Imp. Precision 4 has a cup diameter of 16.41 mm / 0.6461 in compared to 16.10 mm / 0.6339 in on the Bach 8½A — a difference of 0.31 mm / 0.0122 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.