Bach 3C vs GR Technologies 64.7S
The GR Technologies 64.7S has a wider cup diameter, the Bach 3C features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Bach 3C
• Trumpet
Cup diameter16.30 mm / 0.6417 in
Best suited for
All-round versatile — balanced cup for general playing
vs
Mouthpiece B
GR Technologies 64.7S
• Trumpet
Cup diameter16.43 mm / 0.6469 in
Cup Diameter
The GR Technologies 64.7S has a cup diameter of 16.43 mm / 0.6469 in compared to 16.30 mm / 0.6417 in on the Bach 3C — a difference of 0.13 mm / 0.0051 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.