Bach 11¾C vs Bach 12B
The Bach 11¾C has a wider cup diameter, the Bach 12B features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 11¾C
• Cornet
Cup diameter15.60 mm / 0.6142 in
vs
Mouthpiece B
Bach 12B
• Cornet
Cup diameter15.20 mm / 0.5984 in
Cup Diameter
The Bach 11¾C has a cup diameter of 15.60 mm / 0.6142 in compared to 15.20 mm / 0.5984 in on the Bach 12B — a difference of 0.40 mm / 0.0157 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.