Which has a bigger cup — Bach 12E or Kelly 5G?

The Kelly 5G has a cup diameter of 25.40 mm / 1.0000 in compared to 24.50 mm / 0.9646 in on the Bach 12E — a difference of 0.90 mm / 0.0354 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Bach 12E and Kelly 5G?

The Kelly 5G has a — cup while the Bach 12E has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.

Bach 12E vs Kelly 5G

Name: Kelly 5G
Brand: Kelly

The Kelly 5G has a wider cup diameter, the Kelly 5G features a deeper cup.

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 12E

• Trombone

Throat diameter5.85 mm / 0.2303 in

Best suited for

📣High-volume projection — open throat for power

Mouthpiece B

Kelly 5G

• Trombone

Orchestral

Throat diameter—

Best suited for

🎻Orchestral playing — large cup for full, dark tone

📋Symphonic trombone

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 12E details Kelly 5G details Bach 12E equivalents Kelly 5G equivalents

Bach 12E vs Kelly 5G

Playing Characteristics

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What Changes If You Switch?

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