Which has a bigger cup — Bach 8½A or Kelly 4B-UK?

The Kelly 4B-UK has a cup diameter of 16.51 mm / 0.6500 in compared to 16.10 mm / 0.6339 in on the Bach 8½A — a difference of 0.41 mm / 0.0161 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Bach 8½A and Kelly 4B-UK?

The Kelly 4B-UK has a — cup while the Bach 8½A has a very deep cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.

Bach 8½A vs Kelly 4B-UK

Name: Kelly 4B-UK
Brand: Kelly

The Kelly 4B-UK has a wider cup diameter, the Kelly 4B-UK features a deeper cup, the Kelly 4B-UK has a larger throat opening.

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 8½A

• Cornet

Material—

Mouthpiece B

Kelly 4B-UK

• Cornet

Orchestral

MaterialLexan polycarbonate

Best suited for

📣High-volume projection — open throat for power

📋Professional cornet; British brass band

Material

The Bach 8½A is described as unspecified, and the Kelly 4B-UK as Lexan polycarbonate. 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 8½A details Kelly 4B-UK details Bach 8½A equivalents Kelly 4B-UK equivalents

Bach 8½A vs Kelly 4B-UK

Material

Playing Characteristics

What Do These Model Names Mean?

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