Bach 30E vs Yamaha BB-66
The Yamaha BB-66 has a wider cup diameter, the Yamaha BB-66 features a deeper cup, the Yamaha BB-66 has a larger throat opening.
Cup Diameter
The Yamaha BB-66 has a cup diameter of 31.37 mm / 1.2350 in compared to 30.00 mm / 1.1811 in on the Bach 30E — a difference of 1.37 mm / 0.0539 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Yamaha BB-66 has a medium cup while the Bach 30E has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Yamaha BB-66 has a wider throat (8.35 mm / 0.3287 in vs 8.33 mm / 0.3280 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
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.