Bach 1 vs GR Technologies 66CX
The Bach 1 has a wider cup diameter.
Mouthpiece A
Bach 1
• Trumpet
Cup diameter17.50 mm / 0.6890 in
Cup depthVery deep
Rim width—
Throat diameter3.66 mm / 0.1441 in
Backbore—
Finish—
Material—
Best suited for
Orchestral playing — large cup for full, dark tone
vs
Mouthpiece B
GR Technologies 66CX
• Trumpet
Cup diameter16.76 mm / 0.6598 in
Cup depthVery deep
Rim width—
Throat diameter—
Backbore—
Finish—
Material—
Cup Diameter
The Bach 1 has a cup diameter of 17.50 mm / 0.6890 in compared to 16.76 mm / 0.6598 in on the GR Technologies 66CX — a difference of 0.74 mm / 0.0291 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a very deep 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.