Bach 5C vs GR Technologies G66**
The GR Technologies G66** has a wider cup diameter.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 5C
• Trumpet
Cup diameter16.25 mm / 0.6398 in
Best suited for
All-round versatile — balanced cup for general playing
vs
Mouthpiece B
GR Technologies G66**
• Trumpet
Cup diameter16.76 mm / 0.6598 in
Cup Diameter
The GR Technologies G66** has a cup diameter of 16.76 mm / 0.6598 in compared to 16.25 mm / 0.6398 in on the Bach 5C — a difference of 0.51 mm / 0.0201 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.