As a recent convert to horn-speakers I have greatly enjoyed trawling through your website and I have learnt plenty not only about horns but also about questioning my own motives and the desired end result of a possible "from scratch" speaker build.
The Macondo looks inspiring but I do have a question about the mid-range horn.
For the lower frequencies you have put in a lot of effort so that the horns operate comfortably within their ranges (i.e. not to their very base or upper loaded frequencies of the horn geometry). I also assume that when you designed/specified these horns that they were built to the full mouth area for the base frequency and were not truncated/shortened. When I look at the 400Hz MF Horn you seem to use it between about 1kHz and 12.5kHz which is a 5 octave spread from its base frequency...my understanding is that the horn will be direct radiating from 3.2kHz upward (after 3 octaves).
So my question here is whether this 5 octave spread has been a specific design element to suit the Vitavox S2 driver or is it to do with real-estate and limits of raising the height of the Macondo or is there some other reason? I have not been able to find an answer in other threads here so I apologise if this topic has been covered elsewhere.