Which has a bigger cup — Bach 12E or Bob Reeves 5GS?

The Bob Reeves 5GS has a cup diameter of 25.55 mm / 1.0059 in compared to 24.50 mm / 0.9646 in on the Bach 12E — a difference of 1.05 mm / 0.0413 in. A wider cup generally produces a fuller, darker tone but requires more air support.

How does cup depth compare between Bach 12E and Bob Reeves 5GS?

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

Bach 12E vs Bob Reeves 5GS

Name: Bob Reeves 5GS
Brand: Bob Reeves

The Bob Reeves 5GS 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 12E

• Trombone

Throat diameter5.85 mm / 0.2303 in

Best suited for

📣High-volume projection — open throat for power

Mouthpiece B

Bob Reeves 5GS

• Trombone

Throat diameter—

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.