Bach 5C vs Conn Precision 4
The Conn Precision 4 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
Conn Precision 4
• Trumpet
GeneralCup diameter16.41 mm / 0.6461 in
Cup depthMedium
Rim width—
Throat diameter—
Backbore—
Finish—
MaterialSilver-plated brass
Best suited for
All-round versatile — balanced cup for general playing
Players with large lips; close to Bach 2C/Schilke 16C4
Bright tone; same as Model 3 with wide rim
Cup Diameter
The Conn Precision 4 has a cup diameter of 16.41 mm / 0.6461 in compared to 16.25 mm / 0.6398 in on the Bach 5C — a difference of 0.16 mm / 0.0063 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.
Material
The Bach 5C is described as unspecified, and the Conn Precision 4 as Silver-plated brass. Material affects mass, warmth, and how quickly the piece responds.
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.