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Message: <blockquote data-quote="Peter Morris" data-source="post: 140922" data-attributes="member: 652">Re: 60 Degree  DIY Mid HiHere is my attempt at a simple explanation - When the size of the horn is large compared to the wave lengths involved the angle of the horn walls controls the pattern.When the wave lengths become larger the dimensions of the horn mouth become important. The smallest dimension will lose pattern control first. In the case of the XT1464 it’s wider than it is high and the vertical pattern starts to becomes wider than the horizontal pattern at about 1.7KHz. - see the plots in my above post.If you don’t want this to happen then the horn has to higher than it is wide; but that’s tricky. To do that you need to make the horn more like the RCF950 where you have a long throat that exits in a narrow tall slot into the main part of the flare.  The problem with that approach is that the long throat with this type of shape is not as nice acoustically as the nice smooth expansion of the XT1464.With the DIY it’s the same width as the HF horn, so the transition between HF and LF horn works almost perfectly in the horizontal plan.  Vertically the two LF exits form a dipole controlling the vertical pattern.  By selecting the appropriate crossover frequency and the physical dimensions of the HF and MID sections, the two sections blend to achieve reasonably good vertical pattern control, much better that your normal 15” + separate horn for example. FWIW I did my best to model this before I built the prototype. The end result is that the DIY, compared to most speakers of a similar size has an excellent pattern control, both horizontal and vertical.</blockquote>

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