Bach 7 vs Yamaha SL-47S
The Yamaha SL-47S has a wider cup diameter.
Mouthpiece A
Bach 7
• Trombone
Cup diameter24.75 mm / 0.9744 in
Cup depthMedium
Rim width—
Throat diameter5.85 mm / 0.2303 in
Backbore—
Finish—
Material—
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Yamaha SL-47S
• Trombone
Cup diameter24.98 mm / 0.9835 in
Cup depthMedium
Rim width—
Throat diameter5.85 mm / 0.2303 in
BackboreSemi-narrow
Finish—
Material—
Best suited for
High-volume projection — open throat for power
Cup Diameter
The Yamaha SL-47S has a cup diameter of 24.98 mm / 0.9835 in compared to 24.75 mm / 0.9744 in on the Bach 7 — a difference of 0.23 mm / 0.0091 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a medium cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
Throat diameters are essentially identical at 5.85 mm / 0.2303 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.