The Arai horn is a hyperbolic CD (constant directivity) horn designed by Yuichi Arai for “serious room listening.” Compared to other horns we’re used to listening to this one tended to sound better to us on axis and had an incredible smooth and delicate detailed sound. I guess thats where the “serious room listening" comment comes from.

Unlike exponential horns, the hyperbolic contour gives it a smoother, more controlled expansion from throat to mouth. The internal fins are the real trick: without them, high frequencies collapse to the center of the horn above 8kHz, so the fins divide the mouth into identical cells sharing a common origin, keeping dispersion consistent all the way up. The throat adapter piece was an addition we added. The entry for the throat of this horn is square which tends to affect on-axis response a bit, so we added an adpater based on W.E eye form expansion to go from the circular throat of the compression driver to the square. The result (to us) seemed to give the horn a smoother response.