Yamaha HR-31B vs Yamaha HR-32C4
The Yamaha HR-32C4 has a wider cup diameter, the Yamaha HR-32C4 features a deeper cup, the Yamaha HR-32C4 has a larger throat opening.
Cup Diameter
The Yamaha HR-32C4 has a cup diameter of 17.48 mm / 0.6882 in compared to 17.47 mm / 0.6878 in on the Yamaha HR-31B — a difference of 0.01 mm / 0.0004 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Yamaha HR-32C4 has a medium cup while the Yamaha HR-31B has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Yamaha HR-32C4 has a wider throat (3.98 mm / 0.1567 in vs 3.90 mm / 0.1535 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.