IsoFlare: coaxial geometry and listening

What “point source” means

Coaxial means the drive units share an axis. Coincident describes the intention to bring their acoustic centres close together. A point source is an idealised model: a real loudspeaker has dimensions and its behaviour changes with frequency.

Reducing the spacing between the ways addresses one geometric cause of path-length differences as the listener moves in height or angle, particularly where the drivers overlap. This is a potential integration benefit, not a guarantee of perfect time alignment.

Dispersion: the aim and the evidence

The cone and high-frequency waveguide help shape radiation. Fyne associates IsoFlare with a wide listening area and stable imaging. To establish how well a particular model preserves tonal balance off axis, look for horizontal and vertical response curves, especially around the crossover.

An upper-frequency limit or driver diameter does not reveal those curves. Nor does it certify identical response at every seat: stereo geometry and reflections still change with position.

Engineering trade-offs remain

The crossover determines how the two ways combine; waveguide geometry, acoustic phase offsets and diffraction also matter. Coaxial designs must also manage the interaction between cone movement and high-frequency radiation.

These are general design considerations, not measured faults in a particular Fyne loudspeaker. Their magnitude, audibility or advantage over another design cannot be assigned without comparable model-specific measurements at relevant levels.

One principle, different implementations

F500E uses titanium high-frequency diaphragms; F500S and F500 SP use magnesium. The F500S and F500SP standmounts both specify a 150 mm IsoFlare assembly with a 25 mm high-frequency unit, but belong to different families.

IsoFlare also appears in F700/F700SP, F1 and Vintage. Sharing the technology name does not make the drivers, crossover or bass loading identical across those ranges. Check the exact model’s specification.

What to check at a listening session

Start with the height and orientation in the model manual. Compare a centred voice from the main seat and a second position without changing level. That tells you what you hear in that installation; it does not replace a directivity measurement.

• Look for measurement conditions alongside response and sensitivity figures.
• For published dispersion data, check frequency, reference axis and measurement angles.
• Assess the result with placement you can actually use at home.