Which has a bigger cup — Bob Reeves 40/B/X or Kelly 3C?

The Kelly 3C has a cup diameter of 17.02 mm / 0.6701 in compared to 15.88 mm / 0.6252 in on the Bob Reeves 40/B/X — a difference of 1.14 mm / 0.0449 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Bob Reeves 40/B/X and Kelly 3C?

Both mouthpieces share a very deep cup depth, so the sound character from depth alone will be very similar.

Bob Reeves 40/B/X vs Kelly 3C

Name: Kelly 3C
Brand: Kelly

The Kelly 3C has a wider cup diameter.

Overall Comparison Cup Diameter Cup Depth Rim Width Throat Diameter Backbore Finish Material

The taper behind the throat leading to the shank. Affects projection and tone character.

Mouthpiece A

Bob Reeves 40/B/X

• Cornet

BackboreX

Mouthpiece B

Kelly 3C

• Cornet

General

BackboreL

Best suited for

🎻Orchestral playing — large cup for full, dark tone

📣High-volume projection — open throat for power

📋All-purpose mid-range

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.