Bach 12E vs Bach 5
The Bach 5 has a wider cup diameter, the Bach 5 features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 12E
• Trombone
Cup diameter24.50 mm / 0.9646 in
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Bach 5
• Trombone
Cup diameter25.50 mm / 1.0039 in
Best suited for
High-volume projection — open throat for power
Cup Diameter
The Bach 5 has a cup diameter of 25.50 mm / 1.0039 in compared to 24.50 mm / 0.9646 in on the Bach 12E — a difference of 1.00 mm / 0.0394 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.