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Bach 12C vs Bach 5GS (small shank)

The Bach 5GS (small shank) has a wider cup diameter, the Bach 5GS (small shank) features a deeper cup, the Bach 5GS (small shank) 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 12C
    • Trombone
    Cup diameter24.50 mm / 0.9646 in
    Best suited for
    📣High-volume projection — open throat for power
    vs
    Mouthpiece B
      Bach 5GS (small shank)
      • Trombone
      Cup diameter25.50 mm / 1.0039 in
      Best suited for
      🎻Orchestral playing — large cup for full, dark tone
      📣High-volume projection — open throat for power

      Cup Diameter

      The Bach 5GS (small shank) has a cup diameter of 25.50 mm / 1.0039 in compared to 24.50 mm / 0.9646 in on the Bach 12C — a difference of 1.00 mm / 0.0394 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 12C details Bach 5GS (small shank) details Bach 12C equivalents Bach 5GS (small shank) equivalents

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