Giardinelli 25 vs Giardinelli Helleberg
The Giardinelli Helleberg has a wider cup diameter, the Giardinelli Helleberg features a deeper cup.
Cup Diameter
The Giardinelli Helleberg has a cup diameter of 33.30 mm / 1.3110 in compared to 32.60 mm / 1.2835 in on the Giardinelli 25 — a difference of 0.70 mm / 0.0276 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Giardinelli Helleberg has a very deep cup while the Giardinelli 25 has a deep cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
Throat diameters are essentially identical at 8.35 mm / 0.3287 in, so resistance feel will be comparable.
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.