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

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

Mouthpiece A

Kelly 12C

• Trombone

Lead

Throat diameter—

Best suited for

📋Lead trombone; smallest cup

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 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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