Which has a bigger cup — Bach 18C or Bach 20C?

The Bach 18C has a cup diameter of 15.10 mm / 0.5945 in compared to 15.00 mm / 0.5906 in on the Bach 20C — a difference of 0.10 mm / 0.0039 in. A wider cup generally produces a fuller, darker tone but requires more air support.

Bach 18C vs Bach 20C

Name: Bach 20C
Brand: Bach

The Bach 18C has a wider cup diameter.

Overall Comparison Cup Diameter Cup Depth Rim Width Throat Diameter Backbore Finish Material

How deep the cup is, from shallow (brighter, easier high register) to deep (darker, fuller sound).

Mouthpiece A

Bach 18C

• Cornet

Cup depthMedium

Mouthpiece B

Bach 20C

• Cornet

Cup depthMedium

Cup Depth

Both mouthpieces share a medium cup depth, so the sound character from depth alone will be very similar.

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.