Bach 15D vs Bach 18
The Bach 15D has a wider cup diameter, the Bach 18 features a deeper cup.
How deep the cup is, from shallow (brighter, easier high register) to deep (darker, fuller sound).
Mouthpiece A
Bach 15D
• Baritone / Euphonium
Cup depthShallow
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Bach 18
• Baritone / Euphonium
Cup depthMedium
Best suited for
High-volume projection — open throat for power
Cup Depth
The Bach 18 has a medium cup while the Bach 15D has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
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.