Which has a bigger cup — Kelly 51D or Schilke 45B?

The Kelly 51D has a cup diameter of 25.40 mm / 1.0000 in compared to 24.30 mm / 0.9567 in on the Schilke 45B — a difference of 1.10 mm / 0.0433 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Kelly 51D and Schilke 45B?

The Kelly 51D has a — cup while the Schilke 45B has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.

Kelly 51D vs Schilke 45B

Name: Schilke 45B
Brand: Schilke

The Kelly 51D has a wider cup diameter, the Kelly 51D features a deeper cup.

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

Base metal or construction (e.g. brass, stainless steel, plastic). Influences weight, response, and tone color.

Mouthpiece A

Kelly 51D

• Trombone

Professional

MaterialLexan polycarbonate

Best suited for

🎻Orchestral playing — large cup for full, dark tone

📋Professional euphonium and trombone players

Mouthpiece B

Schilke 45B

• Trombone

Material—

Best suited for

📣High-volume projection — open throat for power

Material

The Kelly 51D is described as Lexan polycarbonate, and the Schilke 45B as unspecified. 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.

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Kelly 51D vs Schilke 45B

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