@phusis wrote:
"What about, and maybe when is the diffraction part most troublesome here; what’s inherent to - as a distinct sonic imprinting/coloration - the narrow slot section leading up to the horn widening at every volume level (i.e.: at lower levels as well), or more predominantly at higher, and perhaps only very high SPL’s? My understanding is it’s more the latter than the former, which urges the more pragmatic question of relevance in a given, domestic setting when, or rather if the issue seems to arise only at, say, +120dB levels."
Agreed, diffraction introduces a type of distortion to which the ear has a non-linear response; that is, the sonically detrimental effects of diffraction become more audible and objectionable as the SPL increases. If you’ve ever heard a PA system that sounded increasingly harsh as the volume level went up your instinct may have been that the system was distorting, but it was probably diffraction. Especially if the PA system could do this repeatedly without being destroyed, as power levels that drive speakers or amps into audible distortion can and does cause permanent damage to the speakers.
Fortunately in a home audio setting the SPL demands are not as high, and large diffraction horns that have found favor in home audio tend to be relatively "gentle" diffraction horns. Some of the bigger ones are imo quite benign even at loud home audio listening levels.
@phusis also wrote:
"I find horn size to be a factor as well, certainly with a lower crossover point and trying to maintain a fairly uniform dispersion pattern at the crossover with directivity control all the way down to the crossover. My finding here is that, generally, the larger the horn the less it sounds like a horn, and by that I mean a more relaxed, properly (i.e.: realistically) sized, dense and visceral sphere of sound. What are your thoughts on sheer horn size here?"
Yes!! There are definitely advantages to pushing the crossover point down fairly low, and there are advantages to the fairly narrow and exceptionally uniform radiation pattern of good big horns. And big horns tend to use large-format compression drivers, which ime impart a sense of ease to the music and sense of palpability (for lack of a better term) to the sound images that make it hard to go back to lesser compression drivers, let alone cones ’n’ domes.