Kelly 5G-LS vs Yamaha SL-48S-GP

The Kelly 5G-LS has a wider cup diameter, the Kelly 5G-LS features a deeper cup.

Overall Comparison Cup Diameter Cup Depth Rim Width Throat Diameter Backbore Finish Material
Mouthpiece A
    Kelly 5G-LS
    • Trombone
    Orchestral
    Cup diameter25.40 mm
    Cup depth
    Rim width
    Throat diameter
    BackboreL
    Finish
    MaterialLexan polycarbonate
    Best suited for
    🎻Orchestral playing — large cup for full, dark tone
    📋Symphonic trombone / euphonium
    vs
    Mouthpiece B
      Yamaha SL-48S-GP
      • Trombone
      Cup diameter25.25 mm
      Cup depthMedium
      Rim width
      Throat diameter6.62 mm
      BackboreSemi-wide
      Finish
      Material
      Best suited for
      📣High-volume projection — open throat for power

      Cup Diameter

      The Kelly 5G-LS has a cup diameter of 25.40 mm compared to 25.25 mm on the Yamaha SL-48S-GP — a difference of +0.15 mm. A wider cup generally produces a fuller, darker tone but requires more air support.

      Cup Depth

      The Kelly 5G-LS has a — cup while the Yamaha SL-48S-GP has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.

      Material

      The Kelly 5G-LS is described as Lexan polycarbonate, and the Yamaha SL-48S-GP 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.

      Open in interactive tool + Add third mouthpiece Kelly 5G-LS details Yamaha SL-48S-GP details Kelly 5G-LS equivalents Yamaha SL-48S-GP equivalents