Schilke 59 vs Yamaha SL-YEO-S
The Yamaha SL-YEO-S has a wider cup diameter, 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 28.52 mm / 1.1228 in on the Schilke 59 — a difference of 0.20 mm / 0.0079 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a deep cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Yamaha SL-YEO-S has a wider throat (8.00 mm / 0.3150 in vs 7.54 mm / 0.2969 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.