Bach 1 vs Marcinkiewicz 10S
The Bach 1 has a wider cup diameter, the Marcinkiewicz 10S has a larger throat opening.
Cup Diameter
The Bach 1 has a cup diameter of 17.50 mm / 0.6890 in compared to 16.84 mm / 0.6630 in on the Marcinkiewicz 10S — a difference of 0.66 mm / 0.0260 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a very deep cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Marcinkiewicz 10S 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.