Bach 18C vs Bruno Tilz 305-D 5
The Bruno Tilz 305-D 5 has a wider cup diameter, the Bruno Tilz 305-D 5 features a deeper cup, the Bruno Tilz 305-D 5 has a larger throat opening.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 18C
• Trombone
Cup diameter24.20 mm / 0.9528 in
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Bruno Tilz 305-D 5
• Trombone
CatalogCup diameter26.00 mm / 1.0236 in
Best suited for
High-volume projection — open throat for power
Cup Diameter
The Bruno Tilz 305-D 5 has a cup diameter of 26.00 mm / 1.0236 in compared to 24.20 mm / 0.9528 in on the Bach 18C — a difference of 1.80 mm / 0.0709 in. A wider cup generally produces a fuller, darker tone but requires more air support.
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.