Bach 18D vs Bach 7
The Bach 7 has a wider cup diameter, the Bach 7 features a deeper cup.
Mouthpiece A
Bach 18D
• Baritone / Euphonium
Cup diameter24.20 mm
Cup depthShallow
Rim width—
Throat diameter5.85 mm
Backbore—
Finish—
Material—
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Bach 7
• Baritone / Euphonium
Cup diameter24.75 mm
Cup depthMedium
Rim width—
Throat diameter5.85 mm
Backbore—
Finish—
Material—
Best suited for
High-volume projection — open throat for power
Cup Diameter
The Bach 7 has a cup diameter of 24.75 mm compared to 24.20 mm on the Bach 18D — a difference of +0.55 mm. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bach 7 has a medium cup while the Bach 18D 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, 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.