Bach 5C vs Monette B4LD FL
The Bach 5C has a wider cup diameter, the Monette B4LD FL features a deeper cup.
Cup Diameter
The Bach 5C has a cup diameter of 16.25 mm / 0.6398 in compared to 16.20 mm / 0.6378 in on the Monette B4LD FL — a difference of 0.05 mm / 0.0020 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Monette B4LD FL has a 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
Throat diameters are essentially identical at 3.66 mm / 0.1441 in, so resistance feel will be comparable.
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.