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Bach 12E vs Yamaha SL-51BS

The Yamaha SL-51BS has a wider cup diameter, the Yamaha SL-51BS has a larger throat opening.

Overall Comparison Cup Diameter Cup Depth Rim Width Throat Diameter Backbore Finish Material
Mouthpiece A
    Bach 12E
    • Trombone
    Cup diameter24.50 mm / 0.9646 in
    Cup depthShallow
    Rim width—
    Throat diameter5.85 mm / 0.2303 in
    Backbore—
    Finish—
    Material—
    Best suited for
    📣High-volume projection — open throat for power
    vs
    Mouthpiece B
      Yamaha SL-51BS
      • Trombone
      Cup diameter25.23 mm / 0.9933 in
      Cup depthShallow
      Rim width—
      Throat diameter6.92 mm / 0.2724 in
      BackboreSemi-wide
      Finish—
      Material—
      Best suited for
      📣High-volume projection — open throat for power

      Cup Diameter

      The Yamaha SL-51BS has a cup diameter of 25.23 mm / 0.9933 in compared to 24.50 mm / 0.9646 in on the Bach 12E — a difference of 0.73 mm / 0.0287 in. A wider cup generally produces a fuller, darker tone but requires more air support.

      Cup Depth

      Both mouthpieces share a shallow cup depth, so the sound character from depth alone will be very similar.

      Throat Diameter

      The Yamaha SL-51BS has a wider throat (6.92 mm / 0.2724 in vs 5.85 mm / 0.2303 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.

      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.

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