What amazes me most of those EMGs are the obvious design flaws, and how they deliver a terrific sound nonetheless. I suppose the super-long duct and oversized horn defeat all other aspects. Still, one wanders what would happen with a better designed arm and a real tractrix-contoured duct!
Ah, the Tractrix horns were an entirely different approach, designed by Paul Voigt, as I'm sure you're aware Marco. The EMG and Expert horn systems are not inferior, just different 'technology' - the mathematics (impedance matching and in this case, 4-dimensional modelling of a hemispherical wavefront) were worked out by Percy Wilson; EMG and Expert took his designs and developed them. A few years ago Graham Rankin, Ian Maxted and I were visited by Bjørn Kolbrek, an eminent horn scientist (incidentally he is co-author of an enormous horn speaker textbook which has just been published, and includes comprehensive historical as well as technical content) - he made lots of tests and concluded that the EMG and Expert horns (and the Voigt Tractix) are really not a great deal more primitive than the best hi-fi horns today. Strangely, it seems there are many radically different ways, all complex, to 'solve' horn requirements... (I must add, I'm sounding as if I know a great deal about all this technically, which definitely isn't the case!) I have an EMG Mk Xb and a Mk Xb Oversize arranged for stereo listening - at some point in future I will attach high quality drivers to both and run them from the hi fi system!
Here's a 'panoramic' photo sweeping round two sides of our main room (the Expert Senior is on the right; the hi fi is in the big cabinet):
For that last photograph, a reworking a poem By Samuel Taylor Coleridge...
In Xanadu did Kubla Khan Andy of Britain
A stately pleasure-dome decree:
Where Alph Music, the sacred river, ran
Through caverns measureless to man
Down to a sunless sea...
And the lamp at the ceiling gives a bright light alternating with darker shades of light that makes it still more irreal... Seems kind of Nemo's cave in the deepest of the Nautilus...!