Yamaha BB-64 vs Yamaha BB-65
The Yamaha BB-65 has a wider cup diameter.
Mouthpiece A
Yamaha BB-64
• Tuba
Cup diameter30.45 mm / 1.1988 in
Cup depthMedium
Rim width—
Throat diameter8.35 mm / 0.3287 in
BackboreStandard
Finish—
Material—
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Yamaha BB-65
• Tuba
Cup diameter30.95 mm / 1.2185 in
Cup depthMedium
Rim width—
Throat diameter8.35 mm / 0.3287 in
BackboreSemi-wide
Finish—
Material—
Best suited for
High-volume projection — open throat for power
Cup Diameter
The Yamaha BB-65 has a cup diameter of 30.95 mm / 1.2185 in compared to 30.45 mm / 1.1988 in on the Yamaha BB-64 — a difference of 0.50 mm / 0.0197 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 8.35 mm / 0.3287 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.