Bach 5C vs GR Technologies 66M
The GR Technologies 66M has a wider cup diameter.
Mouthpiece A
Bach 5C
• Trumpet
Cup diameter16.25 mm / 0.6398 in
Cup depthMedium
Rim width—
Throat diameter3.66 mm / 0.1441 in
Backbore—
Finish—
Material—
Best suited for
All-round versatile — balanced cup for general playing
vs
Mouthpiece B
GR Technologies 66M
• Trumpet
Cup diameter16.76 mm / 0.6598 in
Cup depthMedium
Rim width—
Throat diameter—
Backbore—
Finish—
Material—
Cup Diameter
The GR Technologies 66M 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.
Cup Depth
Both mouthpieces share a medium cup depth, so the sound character from depth alone will be very similar.
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.