Bach 1 vs Yamaha TR-17D4
The Bach 1 has a wider cup diameter, the Bach 1 features a deeper cup, the Bach 1 has a larger throat opening.
Cup Diameter
The Bach 1 has a cup diameter of 17.50 mm / 0.6890 in compared to 17.30 mm / 0.6811 in on the Yamaha TR-17D4 — a difference of 0.20 mm / 0.0079 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bach 1 has a very deep cup while the Yamaha TR-17D4 has a deep cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Bach 1 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.