Bach 12B vs Bach 8½A
The Bach 8½A has a wider cup diameter, the Bach 8½A features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 12B
• Cornet
Cup diameter15.20 mm / 0.5984 in
vs
Mouthpiece B
Bach 8½A
• Cornet
Cup diameter16.10 mm / 0.6339 in
Cup Diameter
The Bach 8½A has a cup diameter of 16.10 mm / 0.6339 in compared to 15.20 mm / 0.5984 in on the Bach 12B — a difference of 0.90 mm / 0.0354 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.