Schilke 51D vs Yamaha SL-YEO-S
The Yamaha SL-YEO-S has a wider cup diameter, the Yamaha SL-YEO-S features a deeper cup, the Yamaha SL-YEO-S has a larger throat opening.
Cup Diameter
The Yamaha SL-YEO-S has a cup diameter of 28.72 mm / 1.1307 in compared to 25.55 mm / 1.0059 in on the Schilke 51D — a difference of 3.17 mm / 0.1248 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Yamaha SL-YEO-S has a deep cup while the Schilke 51D has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Yamaha SL-YEO-S has a wider throat (8.00 mm / 0.3150 in vs 7.04 mm / 0.2772 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.