Bach 12E 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.
The narrowest point at the bottom of the cup. Affects resistance, volume, and tone color.
Mouthpiece A
Bach 12E
• Trombone
Throat diameter5.85 mm / 0.2303 in
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Bach 4G
• Trombone
Throat diameter7.01 mm / 0.2760 in
Best suited for
Orchestral playing — large cup for full, dark tone
High-volume projection — open throat for power
Throat Diameter
The Bach 4G has a wider throat (7.01 mm / 0.2760 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.