Bach 3D vs Bach 7D
The Bach 3D has a wider cup diameter.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 3D
• Cornet
Cup diameter16.30 mm / 0.6417 in
vs
Mouthpiece B
Bach 7D
• Cornet
Cup diameter16.20 mm / 0.6378 in
Best suited for
Lead / commercial — shallow cup for brightness and range
Cup Diameter
The Bach 3D has a cup diameter of 16.30 mm / 0.6417 in compared to 16.20 mm / 0.6378 in on the Bach 7D — a difference of 0.10 mm / 0.0039 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.