Home › Trombone › Bach 12C vs Bach 4G

Bach 12C vs Bach 4G

The Bach 4G has a wider cup diameter, the Bach 4G features a deeper cup, the Bach 4G 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 4G
      • Trombone
      Cup diameter26.00 mm / 1.0236 in
      Best suited for
      🎻Orchestral playing — large cup for full, dark tone
      📣High-volume projection — open throat for power

      Cup Diameter

      The Bach 4G has a cup diameter of 26.00 mm / 1.0236 in compared to 24.50 mm / 0.9646 in on the Bach 12C — a difference of 1.50 mm / 0.0591 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 4G details Bach 12C equivalents Bach 4G equivalents

      Compare Bach 12C with others

      Compare Bach 4G with others

      Popular Trombone comparisons

      Browse by specification