Schilke 51 vs Yamaha SL-52S
The Yamaha SL-52S has a wider cup diameter, the Yamaha SL-52S has a larger throat opening.
Cup Diameter
The Yamaha SL-52S has a cup diameter of 25.65 mm / 1.0098 in compared to 25.63 mm / 1.0091 in on the Schilke 51 — a difference of 0.02 mm / 0.0008 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a medium cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Yamaha SL-52S has a wider throat (7.11 mm / 0.2799 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.