Bach 12E vs Yamaha BL-60BL
The Yamaha BL-60BL has a wider cup diameter, the Yamaha BL-60BL has a larger throat opening.
Cup Diameter
The Yamaha BL-60BL has a cup diameter of 27.83 mm / 1.0957 in compared to 24.50 mm / 0.9646 in on the Bach 12E — a difference of 3.33 mm / 0.1311 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a shallow cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Yamaha BL-60BL has a wider throat (6.92 mm / 0.2724 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.