GR Technologies 64SZ vs Yamaha TR-14B4
The Yamaha TR-14B4 has a wider cup diameter.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
GR Technologies 64SZ
• Trumpet
Cup diameter16.26 mm / 0.6402 in
vs
Mouthpiece B
Yamaha TR-14B4
• Trumpet
Cup diameter16.85 mm / 0.6634 in
Cup Diameter
The Yamaha TR-14B4 has a cup diameter of 16.85 mm / 0.6634 in compared to 16.26 mm / 0.6402 in on the GR Technologies 64SZ — a difference of 0.59 mm / 0.0232 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.