Bach 6½AL (large shank) vs Yamaha BL-60L
The Yamaha BL-60L has a wider cup diameter, the Bach 6½AL (large shank) features a deeper cup, the Yamaha BL-60L has a larger throat opening.
Cup Diameter
The Yamaha BL-60L has a cup diameter of 28.25 mm / 1.1122 in compared to 25.40 mm / 1.0000 in on the Bach 6½AL (large shank) — a difference of 2.85 mm / 0.1122 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bach 6½AL (large shank) has a deep cup while the Yamaha BL-60L has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Yamaha BL-60L has a wider throat (8.10 mm / 0.3189 in vs 6.63 mm / 0.2610 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.