Kelly 7C vs Yamaha CR-14ES
The Yamaha CR-14ES has a wider cup diameter, the Yamaha CR-14ES features a deeper cup, the Yamaha CR-14ES has a larger throat opening.
Cup Diameter
The Yamaha CR-14ES has a cup diameter of 16.86 mm / 0.6638 in compared to 16.51 mm / 0.6500 in on the Kelly 7C — a difference of 0.35 mm / 0.0138 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Yamaha CR-14ES has a very deep cup while the Kelly 7C has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Yamaha CR-14ES has a wider throat (3.98 mm / 0.1567 in vs 3.66 mm / 0.1441 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
Material
The Kelly 7C is described as Lexan polycarbonate, and the Yamaha CR-14ES as unspecified. Material affects mass, warmth, and how quickly the piece responds.
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.