Bach 7 vs Yamaha AH-38D4
The Bach 7 has a wider cup diameter, the Yamaha AH-38D4 features a deeper cup, the Bach 7 has a larger throat opening.
Cup Diameter
The Bach 7 has a cup diameter of 24.75 mm / 0.9744 in compared to 18.90 mm / 0.7441 in on the Yamaha AH-38D4 — a difference of 5.85 mm / 0.2303 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Yamaha AH-38D4 has a deep cup while the Bach 7 has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Bach 7 has a wider throat (5.85 mm / 0.2303 in vs 5.25 mm / 0.2067 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.