Kelly 18 vs Kelly 24AW
The Kelly 18 has a wider cup diameter, the Kelly 18 features a deeper cup.
Mouthpiece A
Kelly 18
• Tuba
GeneralCup diameter32.77 mm / 1.2902 in
Cup depth
Rim width—
Throat diameter—
BackboreM
Finish—
MaterialLexan polycarbonate
Best suited for
Orchestral playing — large cup for full, dark tone
Industry-standard tuba
vs
Mouthpiece B
Kelly 24AW
• Tuba
GeneralCup diameter31.24 mm / 1.2299 in
Cup depthVery deep
Rim width—
Throat diameter—
BackboreXL
Finish—
MaterialLexan polycarbonate
Best suited for
Orchestral playing — large cup for full, dark tone
Tuba / sousaphone
Cup Diameter
The Kelly 18 has a cup diameter of 32.77 mm / 1.2902 in compared to 31.24 mm / 1.2299 in on the Kelly 24AW — a difference of 1.53 mm / 0.0602 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Kelly 18 has a — cup while the Kelly 24AW has a very deep cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Material
Both mouthpieces share the same listed material (Lexan polycarbonate).
Which is better?
Both mouthpieces are categorized as "General" — the physical dimensions above will determine which suits your embouchure and playing style better.