Bach 8¾C vs Bach 9D
The Bach 8¾C has a wider cup diameter.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 8¾C
• Cornet
Cup diameter16.10 mm / 0.6339 in
Best suited for
Lead / commercial — shallow cup for brightness and range
vs
Mouthpiece B
Bach 9D
• Cornet
Cup diameter16.05 mm / 0.6319 in
Best suited for
Lead / commercial — shallow cup for brightness and range
Cup Diameter
The Bach 8¾C has a cup diameter of 16.10 mm / 0.6339 in compared to 16.05 mm / 0.6319 in on the Bach 9D — a difference of 0.05 mm / 0.0020 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.