Bach 5GS (large shank) vs Yamaha SL-48DL
The Bach 5GS (large shank) has a wider cup diameter.
Mouthpiece A
Bach 5GS (large shank)
• Trombone
Cup diameter25.50 mm / 1.0039 in
Cup depthDeep
Rim width—
Throat diameter6.63 mm / 0.2610 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
Yamaha SL-48DL
• Trombone
Cup diameter25.25 mm / 0.9941 in
Cup depthDeep
Rim width—
Throat diameter6.62 mm / 0.2606 in
BackboreSemi-narrow
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 (large shank) has a cup diameter of 25.50 mm / 1.0039 in compared to 25.25 mm / 0.9941 in on the Yamaha SL-48DL — a difference of 0.25 mm / 0.0098 in. 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
Throat diameters are essentially identical at 6.63 mm / 0.2610 in, so resistance feel will be comparable.
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.