Bach 15 vs Bruno Tilz 304- A 1
The Bach 15 has a wider cup diameter, the Bach 15 features a deeper cup, the Bach 15 has a larger throat opening.
Cup Diameter
The Bach 15 has a cup diameter of 24.40 mm / 0.9606 in compared to 22.00 mm / 0.8661 in on the Bruno Tilz 304- A 1 — a difference of 2.40 mm / 0.0945 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bach 15 has a deep cup while the Bruno Tilz 304- A 1 has a very shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Bach 15 has a wider throat (5.85 mm / 0.2303 in vs 4.40 mm / 0.1732 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.