Bach 12E vs Schilke 42B
The Bach 12E has a wider cup diameter, the Schilke 42B features a deeper cup, the Schilke 42B has a larger throat opening.
Cup Diameter
The Bach 12E has a cup diameter of 24.50 mm / 0.9646 in compared to 22.99 mm / 0.9051 in on the Schilke 42B — a difference of 1.51 mm / 0.0594 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Schilke 42B has a medium 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 Schilke 42B has a wider throat (5.95 mm / 0.2343 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.