A Differential Dispersion horn has a 3D trapezoid dispersion pattern which covers a room more evenly than a system with a conventional, fixed-dispersion X° x Y° type horn.
With a conventional X° x Y° horn, the speaker is usually placed bove head height and aimed towards the centre of the audience. This produces an imperfect coverage pattern which misses out some areas — particularly side areas close to the loudspeaker.
In contrast, a CDD Coaxial Differential Dispersion system produces a rectangular coverage pattern to reach all corners of the audience, and wide horizontal coverage is achieved very close to the loudspeaker. Walking the room, the consistency in frequency response and SPL — both close to the loudspeaker and further back — is exceptional.
The improved coverage close-up also means that CDD speakers can be spaced further apart in some instances, reducing overall speaker count.