Coherent wavefront summation in line-source high-frequency sections

Two sources, one wavefront

Two sources radiating the same signal sum coherently where their path lengths match, and interfere destructively where the difference approaches half a wavelength. At 10 kHz the wavelength is 34 millimetres, so two high-frequency drivers a metre apart in free space produce a comb of lobes and nulls rather than coverage. This is why a line of separate horns does not make a line source.

The classical requirement, formalised in wavefront sculpture work in the 1990s, is that adjacent sources either sit within a fraction of a wavelength of each other or radiate a flat, contiguous wavefront over most of the array face. At high frequencies only the second condition is achievable, and it is a geometry problem: the waveguide must transform the output of a compression driver's small exit into a tall, flat, in-phase ribbon.

What the mouth controls

A waveguide holds its rated coverage only while its mouth is large compared with the wavelength. Below that regime the pattern widens toward omnidirectional regardless of the flare's shape; above it, the wall geometry sets the angle. The larger the continuous mouth an array element presents, the lower the frequency to which the array keeps directional control, which is why full-face waveguides are a defining feature of large-format elements.

The IsoPhase geometry

IsoPhase is the SSOUNDS waveguide geometry that sums multiple compression drivers into one isophasic mouth: a surface over which the wavefront leaves with matched phase. Adjacent cabinets then present their mouths edge to edge, so a hang approximates one continuous ribbon rather than a stack of discrete radiators. Coverage stays even across the audience plane, and summation remains predictable as elements are added, which is the property array prediction depends on.