Bach 12E vs Bach 30CB
The Bach 30CB has a wider cup diameter, the Bach 30CB features a deeper cup.
Mouthpiece A
Bach 12E
• Trombone
Cup diameter24.50 mm / 0.9646 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
vs
Mouthpiece B
Bach 30CB
• Trombone
Cup diameter30.00 mm / 1.1811 in
Cup depthVery deep
Rim width—
Throat diameter—
Backbore—
Finish—
Material—
Best suited for
Orchestral playing — large cup for full, dark tone
Cup Diameter
The Bach 30CB has a cup diameter of 30.00 mm / 1.1811 in compared to 24.50 mm / 0.9646 in on the Bach 12E — a difference of 5.50 mm / 0.2165 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bach 30CB has a very deep cup while the Bach 12E 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.