Schilke 66 vs Schilke GEIB
The Schilke GEIB has a wider cup diameter, the Schilke 66 features a deeper cup, the Schilke 66 has a larger throat opening.
Cup Diameter
The Schilke GEIB has a cup diameter of 32.76 mm / 1.2898 in compared to 31.52 mm / 1.2409 in on the Schilke 66 — a difference of 1.24 mm / 0.0488 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Schilke 66 has a medium cup while the Schilke GEIB has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Schilke 66 has a wider throat (8.33 mm / 0.3280 in vs 7.94 mm / 0.3126 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.