Monette Cornet C4LVS vs Yamaha CR-9C4L
The Yamaha CR-9C4L has a wider cup diameter, the Monette Cornet C4LVS has a larger throat opening.
Cup Diameter
The Yamaha CR-9C4L has a cup diameter of 16.28 mm / 0.6409 in compared to 16.20 mm / 0.6378 in on the Monette Cornet C4LVS — a difference of 0.08 mm / 0.0031 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a medium cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Monette Cornet C4LVS has a wider throat (3.66 mm / 0.1441 in vs 3.65 mm / 0.1437 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.