Bach 12E vs Kelly BASS-BONE-LS
The Kelly BASS-BONE-LS has a wider cup diameter, the Kelly BASS-BONE-LS features a deeper cup.
Cup Diameter
The Kelly BASS-BONE-LS has a cup diameter of 27.69 mm / 1.0902 in compared to 24.50 mm / 0.9646 in on the Bach 12E — a difference of 3.19 mm / 0.1256 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Kelly BASS-BONE-LS has a — cup while the Bach 12E has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Material
The Bach 12E is described as unspecified, and the Kelly BASS-BONE-LS 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.