Bob Reeves 43N/B/s vs Kelly 7C
The Bob Reeves 43N/B/s has a wider cup diameter, the Bob Reeves 43N/B/s features a deeper cup.
Cup Diameter
The Bob Reeves 43N/B/s has a cup diameter of 17.07 mm / 0.6720 in compared to 16.51 mm / 0.6500 in on the Kelly 7C — a difference of 0.56 mm / 0.0220 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bob Reeves 43N/B/s has a very deep cup while the Kelly 7C has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Material
The Bob Reeves 43N/B/s is described as unspecified, and the Kelly 7C as Lexan polycarbonate. 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.