Schilke 42B vs Schilke 45B
The Schilke 45B has a wider cup diameter.
Mouthpiece A
Schilke 42B
• Trombone
Cup diameter22.99 mm / 0.9051 in
Cup depthMedium
Rim width—
Throat diameter5.95 mm / 0.2343 in
Backbore15/64 .2344"
Finish—
Material—
Best suited for
High-volume projection — open throat for power
vs
Mouthpiece B
Schilke 45B
• Trombone
Cup diameter24.30 mm / 0.9567 in
Cup depthMedium
Rim width—
Throat diameter5.95 mm / 0.2343 in
Backbore15/64 .2344"
Finish—
Material—
Best suited for
High-volume projection — open throat for power
Cup Diameter
The Schilke 45B has a cup diameter of 24.30 mm / 0.9567 in compared to 22.99 mm / 0.9051 in on the Schilke 42B — a difference of 1.31 mm / 0.0516 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 5.95 mm / 0.2343 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.