Bach 12 vs Bach 5GS (small shank)
The Bach 5GS (small shank) has a wider cup diameter, the Bach 5GS (small shank) has a larger throat opening.
Mouthpiece A
Bach 12
• Baritone / Euphonium
Cup diameter24.50 mm
Cup depthDeep
Rim width—
Throat diameter5.85 mm
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 5GS (small shank)
• Baritone / Euphonium
Cup diameter25.50 mm
Cup depthDeep
Rim width—
Throat diameter6.63 mm
Backbore—
Finish—
Material—
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 compared to 24.50 mm on the Bach 12 — a difference of +1.00 mm. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a deep cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Bach 5GS (small shank) has a wider throat (6.63 mm vs 5.85 mm). 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.