Bach 18 vs Bach 18C
the Bach 18 features a deeper cup.
Mouthpiece A
Bach 18
• Trombone
Cup diameter24.20 mm / 0.9528 in
Cup depthMedium
Rim width—
Throat diameter5.85 mm / 0.2303 in
Backbore—
Finish—
Material—
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Bach 18C
• Trombone
Cup diameter24.20 mm / 0.9528 in
Cup depthShallow
Rim width—
Throat diameter5.85 mm / 0.2303 in
Backbore—
Finish—
Material—
Best suited for
High-volume projection — open throat for power
Cup Diameter
Both mouthpieces have virtually identical cup diameters at 24.20 mm / 0.9528 in.
Cup Depth
The Bach 18 has a medium cup while the Bach 18C has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
Throat diameters are essentially identical at 5.85 mm / 0.2303 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.