Bach Mega Tone 1D vs Yamaha TR-14B4
The Bach Mega Tone 1D has a wider cup diameter, the Bach Mega Tone 1D has a larger throat opening.
Cup Diameter
The Bach Mega Tone 1D has a cup diameter of 17.00 mm / 0.6693 in compared to 16.85 mm / 0.6634 in on the Yamaha TR-14B4 — a difference of 0.15 mm / 0.0059 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 Bach Mega Tone 1D has a wider throat (3.73 mm / 0.1469 in vs 3.65 mm / 0.1437 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.