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Bach 1½GM vs Bach 12C

The Bach 1½GM has a wider cup diameter, the Bach 1½GM features a deeper cup, the Bach 1½GM has a larger throat opening.

Overall Comparison Cup Diameter Cup Depth Rim Width Throat Diameter Backbore Finish Material
Mouthpiece A
    Bach 1½GM
    • Trombone
    Cup diameter27.00 mm / 1.0630 in
    Cup depthVery deep
    Rim width—
    Throat diameter8.10 mm / 0.3189 in
    Backbore—
    Finish—
    Material—
    Best suited for
    🎻Orchestral playing — large cup for full, dark tone
    📣High-volume projection — open throat for power
    vs
    Mouthpiece B
      Bach 12C
      • 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

      Cup Diameter

      The Bach 1½GM has a cup diameter of 27.00 mm / 1.0630 in compared to 24.50 mm / 0.9646 in on the Bach 12C — a difference of 2.50 mm / 0.0984 in. A wider cup generally produces a fuller, darker tone but requires more air support.

      Cup Depth

      The Bach 1½GM has a very deep cup while the Bach 12C has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.

      Throat Diameter

      The Bach 1½GM has a wider throat (8.10 mm / 0.3189 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.

      Open in interactive tool + Add third mouthpiece Bach 1½GM details Bach 12C details Bach 1½GM equivalents Bach 12C equivalents

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