Bach 30CB vs Yamaha SL-48S-GP
The Bach 30CB has a wider cup diameter, the Bach 30CB features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 30CB
• Trombone
Cup diameter30.00 mm / 1.1811 in
Best suited for
Orchestral playing — large cup for full, dark tone
vs
Mouthpiece B
Yamaha SL-48S-GP
• Trombone
Cup diameter25.25 mm / 0.9941 in
Best suited for
High-volume projection — open throat for power
Cup Diameter
The Bach 30CB has a cup diameter of 30.00 mm / 1.1811 in compared to 25.25 mm / 0.9941 in on the Yamaha SL-48S-GP — a difference of 4.75 mm / 0.1870 in. A wider cup generally produces a fuller, darker tone but requires more air support.
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.