Bach 1 vs Bach 10½A
The Bach 1 has a wider cup diameter.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 1
• Cornet
Cup diameter17.50 mm / 0.6890 in
Best suited for
Orchestral playing — large cup for full, dark tone
vs
Mouthpiece B
Bach 10½A
• Cornet
Cup diameter15.90 mm / 0.6260 in
Cup Diameter
The Bach 1 has a cup diameter of 17.50 mm / 0.6890 in compared to 15.90 mm / 0.6260 in on the Bach 10½A — a difference of 1.60 mm / 0.0630 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.