Bach 17C vs Bach 18C
Both mouthpieces share similar core dimensions — the differences are in the details.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 17C
• Cornet
Cup diameter15.10 mm / 0.5945 in
vs
Mouthpiece B
Bach 18C
• Cornet
Cup diameter15.10 mm / 0.5945 in
Cup Diameter
Both mouthpieces have virtually identical cup diameters at 15.10 mm / 0.5945 in.
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.