Bach 12E 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 24.50 mm / 0.9646 in on the Bach 12E — a difference of 4.22 mm / 0.1661 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 Bach 12E has a shallow 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 5.85 mm / 0.2303 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.