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Bach 18 vs Yamaha SL-48L-GP

The Yamaha SL-48L-GP has a wider cup diameter, the Yamaha SL-48L-GP has a larger throat opening.

Overall Comparison Cup Diameter Cup Depth Rim Width Throat Diameter Backbore Finish Material
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
    Bach 18
    • Trombone
    Cup diameter24.20 mm / 0.9528 in
    Best suited for
    📣High-volume projection — open throat for power
    vs
    Mouthpiece B
      Yamaha SL-48L-GP
      • Trombone
      Cup diameter25.25 mm / 0.9941 in
      Best suited for
      📣High-volume projection — open throat for power

      Cup Diameter

      The Yamaha SL-48L-GP has a cup diameter of 25.25 mm / 0.9941 in compared to 24.20 mm / 0.9528 in on the Bach 18 — a difference of 1.05 mm / 0.0413 in. A wider cup generally produces a fuller, darker tone but requires more air support.

      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 Bach 18 details Yamaha SL-48L-GP details Bach 18 equivalents Yamaha SL-48L-GP equivalents

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