Bach 1½C vs Bob Reeves RP5
The Bach 1½C has a wider cup diameter, the Bach 1½C features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 1½C
• Trumpet
Cup diameter17.00 mm / 0.6693 in
vs
Mouthpiece B
Bob Reeves RP5
• Trumpet
Cup diameter16.47 mm / 0.6484 in
Cup Diameter
The Bach 1½C has a cup diameter of 17.00 mm / 0.6693 in compared to 16.47 mm / 0.6484 in on the Bob Reeves RP5 — a difference of 0.53 mm / 0.0209 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.