Which has a bigger cup — Bach 15D or Bach 18D?

The Bach 15D has a cup diameter of 24.40 mm / 0.9606 in compared to 24.20 mm / 0.9528 in on the Bach 18D — a difference of 0.20 mm / 0.0079 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Bach 15D and Bach 18D?

Both mouthpieces share a shallow cup depth, so the sound character from depth alone will be very similar.

Bach 15D vs Bach 18D

Name: Bach 18D
Brand: Bach

The Bach 15D has a wider cup diameter.

Overall Comparison Cup Diameter Cup Depth Rim Width Throat Diameter Backbore Finish Material

The narrowest point at the bottom of the cup. Affects resistance, volume, and tone color.

Mouthpiece A

Bach 15D

• Trombone

Throat diameter5.85 mm / 0.2303 in

Best suited for

📣High-volume projection — open throat for power

Mouthpiece B

Bach 18D

• Trombone

Throat diameter5.85 mm / 0.2303 in

Best suited for

📣High-volume projection — open throat for power

Throat Diameter

Throat diameters are essentially identical at 5.85 mm / 0.2303 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.

Open in interactive tool + Add third mouthpiece Bach 15D details Bach 18D details Bach 15D equivalents Bach 18D equivalents

Bach 15D vs Bach 18D

Throat Diameter

Playing Characteristics

What Do These Model Names Mean?

What Changes If You Switch?

Which is better?

Compare Bach 15D with others

Compare Bach 18D with others

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