Denis Wick 9BL vs Yamaha SL-48L
The Yamaha SL-48L has a wider cup diameter, the Denis Wick 9BL has a larger throat opening.
Cup Diameter
The Yamaha SL-48L has a cup diameter of 25.25 mm / 0.9941 in compared to 25.00 mm / 0.9843 in on the Denis Wick 9BL — 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 medium cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Denis Wick 9BL has a wider throat (6.66 mm / 0.2622 in vs 6.62 mm / 0.2606 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.