Bach 18 vs Marcinkiewicz 3
The Marcinkiewicz 3 has a wider cup diameter, the Bach 18 features a deeper cup, the Marcinkiewicz 3 has a larger throat opening.
Cup Diameter
The Marcinkiewicz 3 has a cup diameter of 17.91 mm / 0.7051 in compared to 16.15 mm / 0.6358 in on the Bach 18 — a difference of 1.76 mm / 0.0693 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bach 18 has a medium cup while the Marcinkiewicz 3 has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Marcinkiewicz 3 has a wider throat (5.41 mm / 0.2130 in vs 4.50 mm / 0.1772 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.