# The first Making of a William Neile ALO SE Horn

Some time ago I presented the first article about my development of the ALO William Neile horn type and the underlying construction method. Although, most of my previous worksheets use a super ellipse for each 3D layer / spline along the horn axis. To have an alternative option for William Neile horns I have implemented the the necessary math together with evenly distributed Neile parabolas used in this context to build up the horizontal construction wave front. All William Neile (WN) horns based on the super ellipse algorithm will get the extension “SE” in their name.

By varying the Lamé exponent of the super ellipse formula many different shapes from elliptical to almost rectangular are possible. At throat everything always starts with a Lamé exponent of 2 which indicates an ideal ellipse. Of course, if major and minor axis of the ellipse are equal there will results a perfect circle at throat. If major and minor axis differ an ellipse will result. Generally, the major axis is the horizontal plane because it is intended to radiate more broad compared to the vertical plane (minor axis). For higher Lamé exponents of the super ellipse formula the  resulting shape will be an almost rectangular spline but a transition function is needed to provide a smooth transition from exponent 2 to higher values along the horn axis. A very similar procedure was already used for my spherical wave horn (SWH) and JMLC worksheets.

This article is about the first making of such a horn by DonVK who much preferred the native elliptical shape and asked for my assistance to optimize a horn for his setup. Finally, we ended by with two horn of different cut-off. This article describes the making of the first smaller version.

It is quite a long time ago since I wrote my last article about William Neile Horns. There was definitely considerable progress exploring and refining this new type of horns, but unfortunately the lack of spare time did not allow it to be documented. The attentive reader will certainly not have missed the fact that one of my fundamental goals is to achieve a good acoustic horn loading almost down to the desired cut-off, but the William Neil horns presented so far behave more or less like classic waveguides with regard to horn loading as there is no visible cut-off, instead of this a very slight roll off of the radiation impedance towards low frequencies happened. Although, some people might in fact prefer the loading properties of my first William Neile horns.