The second part of this article series deals with 1in4 (1.4 inch) William Neile ALO horn. This is the next logical step on my agenda. Also because the new 1in4 William Neile ALO horn is supposed to replace my current TH4001 which is a good sounding horn so the expectations are set quite high. The category of the so-called fin horns seems to me to be quite popular and their good sound properties are usually reported. However, I am of the opinion that the known underlying assumption for the construction of fin horns, especially the fin shape and arrangement, does not lead to a coherent wavefront over all frequencies at the exit of the individual channels. I have developed an improved version of different curved fin arrangement which implements equal path lengths of each channel together with the right and exact opening angle for proper exponential acoustic loading, but this is another story. So to speak the TH4001 is a good performer but has some serious design issues. The William Neile ALO horns use what I call natural dispersion instead but with it’s own limits one has to accept. What I want to say is that it is not possible to achieve such wide radiation for a very low-loading horn similar to a fin horn. In my opinion, this is not necessary at all for use in normal listening rooms. But many are somehow still of the opinion that some kind of cinema horns with extremely wide dispersion should be set up at home but these were intended to reach hundreds of people in a large cinema hall with evenly distributed sound impressions at every single seat. A slightly narrower dispersion can definitely be an advantage, especially in smaller listening rooms and when only a few listening positions in the room have to be considered. The intrinsic problems of fin horns, which are related to the the individual channels (shape, length, arrangement), such as cavity resonances or excitations or the suboptimal addition to a coherent wave front, cannot occur with a natural dispersion horn. For example, anyone who doubts that e.g. 30 degrees of even radiation can be sufficient should mark this angle with two strings on the floor from each loudspeaker to the listening position and preferably with the loudspeakers angled slightly inwards and then look at the area of even radiation delimited by the strings on the floor. My 1in4 William Neile ALO horn will achieve about twice as wide dispersion in the horizontal plane.
Encouraged by the excellent simulation results of my William Neile ALO horns the next logical step was to have a prototype made. But is not so easy to find someone who is willing to spend the time and invest some money / material to produce a prototype. Luckily, I got a hint to contact member pelanj at diyaudio.com forum. Believe me that I remember very well one of his first words: “I am excited and honored to be a part of it.” This indeed was the kick-off of our collaboration. It was a pleasure to work with him so far so that I am now able to proudly present the first prototype based on my own horn design made by Jaroslav. If any desire should arise to purchase one of my William Neile horns, then Jaroslav is the only person so far who is allowed to make them in Europe. At this point I would like to emphasize again that I do not charge any license fees or receive any other profit sharing. Any cost calculation is not at my discretion.
A very special thanks goes to Roland (Ro808), who was indeed the first to recognize the potential of my work and contacted me through a forum some years ago and played a not inconsiderable part that I am running this blog.