Bach 5C vs Marcinkiewicz 11S
The Marcinkiewicz 11S has a wider cup diameter, the Marcinkiewicz 11S features a deeper cup, the Marcinkiewicz 11S has a larger throat opening.
Cup Diameter
The Marcinkiewicz 11S has a cup diameter of 16.31 mm / 0.6421 in compared to 16.25 mm / 0.6398 in on the Bach 5C — a difference of 0.06 mm / 0.0024 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Marcinkiewicz 11S has a very deep cup while the Bach 5C has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Marcinkiewicz 11S has a wider throat (3.73 mm / 0.1469 in vs 3.66 mm / 0.1441 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.