Bach 1½C vs Bach 5V
The Bach 1½C has a wider cup diameter, the Bach 5V features a deeper cup, the Bach 5V has a larger throat opening.
Cup Diameter
The Bach 1½C has a cup diameter of 17.00 mm / 0.6693 in compared to 16.25 mm / 0.6398 in on the Bach 5V — a difference of 0.75 mm / 0.0295 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bach 5V has a very deep cup while the Bach 1½C has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Bach 5V has a wider throat (4.09 mm / 0.1610 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.