Which has a bigger cup — Kelly 12C or Yamaha SL-YEO-S?

The Yamaha SL-YEO-S has a cup diameter of 28.72 mm / 1.1307 in compared to 24.13 mm / 0.9500 in on the Kelly 12C — a difference of 4.59 mm / 0.1807 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Kelly 12C and Yamaha SL-YEO-S?

The Yamaha SL-YEO-S has a deep cup while the Kelly 12C has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.

Kelly 12C vs Yamaha SL-YEO-S

Name: Yamaha SL-YEO-S
Brand: Yamaha

The Yamaha SL-YEO-S has a wider cup diameter, the Yamaha SL-YEO-S features a deeper cup.

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

Surface plating or treatment (e.g. silver plate, gold trim). Affects feel, durability, and appearance.

Mouthpiece A

Kelly 12C

• Trombone

Lead

Finish—

Best suited for

📋Lead trombone; smallest cup

Mouthpiece B

Yamaha SL-YEO-S

• Trombone

Finish—

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 12C details Yamaha SL-YEO-S details Kelly 12C equivalents Yamaha SL-YEO-S equivalents

Kelly 12C vs Yamaha SL-YEO-S

Playing Characteristics

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What Changes If You Switch?

Which is better?

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