Schilke 51 vs Schilke 51D
The Schilke 51 has a wider cup diameter.
Mouthpiece A
Schilke 51
• Trombone
Cup diameter25.63 mm / 1.0091 in
Cup depthMedium
Rim width—
Throat diameter7.04 mm / 0.2772 in
BackboreJ .277"
Finish—
Material—
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Schilke 51D
• Trombone
Cup diameter25.55 mm / 1.0059 in
Cup depthMedium
Rim width—
Throat diameter7.04 mm / 0.2772 in
BackboreJ .277"
Finish—
Material—
Best suited for
High-volume projection — open throat for power
Cup Diameter
The Schilke 51 has a cup diameter of 25.63 mm / 1.0091 in compared to 25.55 mm / 1.0059 in on the Schilke 51D — a difference of 0.08 mm / 0.0031 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 7.04 mm / 0.2772 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.