Bach 6½AL (large shank) vs Bob Reeves 5GS
The Bob Reeves 5GS has a wider cup diameter, the Bach 6½AL (large shank) features a deeper cup.
Mouthpiece A
Bach 6½AL (large shank)
• Trombone
Cup diameter25.40 mm / 1.0000 in
Cup depthDeep
Rim width—
Throat diameter6.63 mm / 0.2610 in
Backbore—
Finish—
Material—
Best suited for
Orchestral playing — large cup for full, dark tone
High-volume projection — open throat for power
vs
Mouthpiece B
Bob Reeves 5GS
• Trombone
Cup diameter25.55 mm / 1.0059 in
Cup depthShallow
Rim width—
Throat diameter—
Backbore—
Finish—
Material—
Cup Diameter
The Bob Reeves 5GS has a cup diameter of 25.55 mm / 1.0059 in compared to 25.40 mm / 1.0000 in on the Bach 6½AL (large shank) — a difference of 0.15 mm / 0.0059 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bach 6½AL (large shank) has a deep cup while the Bob Reeves 5GS has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
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.