Which has a bigger cup — Kelly 51D or Yamaha SL-YEO-S?

The Yamaha SL-YEO-S has a cup diameter of 28.72 mm / 1.1307 in compared to 25.40 mm / 1.0000 in on the Kelly 51D — a difference of 3.32 mm / 0.1307 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Kelly 51D and Yamaha SL-YEO-S?

The Kelly 51D has a — cup while the Yamaha SL-YEO-S has a deep cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.

Kelly 51D vs Yamaha SL-YEO-S

Name: Yamaha SL-YEO-S
Brand: Yamaha

The Yamaha SL-YEO-S 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

The narrowest point at the bottom of the cup. Affects resistance, volume, and tone color.

Mouthpiece A

Kelly 51D

• Trombone

Professional

Throat diameter—

Best suited for

🎻Orchestral playing — large cup for full, dark tone

📋Professional euphonium and trombone players

Mouthpiece B

Yamaha SL-YEO-S

• Trombone

Throat diameter8.00 mm / 0.3150 in

Best suited for

🎻Orchestral playing — large cup for full, dark tone

📣High-volume projection — open throat for power

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.

Open in interactive tool + Add third mouthpiece Kelly 51D details Yamaha SL-YEO-S details Kelly 51D equivalents Yamaha SL-YEO-S equivalents

Kelly 51D vs Yamaha SL-YEO-S

Playing Characteristics

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