Bach 3D vs Bach 7D
The Bach 3D has a wider cup diameter.
Mouthpiece A
Bach 3D
• Cornet
Cup diameter16.30 mm / 0.6417 in
Cup depthShallow
Rim width—
Throat diameter3.66 mm / 0.1441 in
Backbore—
Finish—
Material—
vs
Mouthpiece B
Bach 7D
• Cornet
Cup diameter16.20 mm / 0.6378 in
Cup depthShallow
Rim width—
Throat diameter3.66 mm / 0.1441 in
Backbore—
Finish—
Material—
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.
Cup Depth
Both mouthpieces share a shallow cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
Throat diameters are essentially identical at 3.66 mm / 0.1441 in, so resistance feel will be comparable.
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.