Bach 5B vs Marcinkiewicz E14B. Shew #1
The Marcinkiewicz E14B. Shew #1 has a wider cup diameter, the Bach 5B has a larger throat opening.
Cup Diameter
The Marcinkiewicz E14B. Shew #1 has a cup diameter of 16.81 mm / 0.6618 in compared to 16.25 mm / 0.6398 in on the Bach 5B — a difference of 0.56 mm / 0.0220 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a deep cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Bach 5B has a wider throat (3.66 mm / 0.1441 in vs 3.56 mm / 0.1402 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.