Which has a bigger cup — Bach 12C or Kelly JAZZ-LS-SS?

The Kelly JAZZ-LS-SS has a cup diameter of 25.65 mm / 1.0098 in compared to 24.50 mm / 0.9646 in on the Bach 12C — a difference of 1.15 mm / 0.0453 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Bach 12C and Kelly JAZZ-LS-SS?

The Kelly JAZZ-LS-SS has a — cup while the Bach 12C has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.

Bach 12C vs Kelly JAZZ-LS-SS

Name: Kelly JAZZ-LS-SS
Brand: Kelly

The Kelly JAZZ-LS-SS has a wider cup diameter, the Kelly JAZZ-LS-SS features a deeper cup.

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

Base metal or construction (e.g. brass, stainless steel, plastic). Influences weight, response, and tone color.

Mouthpiece A

Bach 12C

• Trombone

Material—

Best suited for

📣High-volume projection — open throat for power

Mouthpiece B

Kelly JAZZ-LS-SS

• Trombone

Jazz

Material316 Surgical Stainless Steel

Best suited for

🎻Orchestral playing — large cup for full, dark tone

📋Jazz solo trombone

Material

The Bach 12C is described as unspecified, and the Kelly JAZZ-LS-SS as 316 Surgical Stainless Steel. Material affects mass, warmth, and how quickly the piece responds.

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 12C details Kelly JAZZ-LS-SS details Bach 12C equivalents Kelly JAZZ-LS-SS equivalents

Bach 12C vs Kelly JAZZ-LS-SS

Material

Playing Characteristics

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