Bach 7 vs Bach 9
The Bach 7 has a wider cup diameter.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 7
• Cornet
Cup diameter16.20 mm / 0.6378 in
vs
Mouthpiece B
Bach 9
• Cornet
Cup diameter16.05 mm / 0.6319 in
Cup Diameter
The Bach 7 has a cup diameter of 16.20 mm / 0.6378 in compared to 16.05 mm / 0.6319 in on the Bach 9 — a difference of 0.15 mm / 0.0059 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.