Seriously. There are 3 ‘plausible’ causes of this perceived effect with horn subs, that I see thrown about (sorry):
1. They cheat the inverse square law.
2. They have a narrower coverage pattern than the same size stack of ported boxes.
3. The lower levels of harmonic distortion mean they’re driven at higher SPL to achieve the same tonal threshold of ‘loud enough’.
The first one was quite deftly tackled in a paper by James Hipperson and pals a few years back.
I keep meaning to write a much shorter version of my dissertation investigating the second one. There is a difference in pattern narrowing for arrays of horn subs versus ported ones! However it’s the ported boxes that become narrower at a realistic upper cutoff (say 125Hz) and it doesn’t happen until you’ve got a pretty obscene stack size for typical frontal areas of touring subs - like 3 high, 12 wide without any gaps.
There are two anomalies:
- Arrays of horn subs that push past a recommended ‘aspect ratio’ of height to width
- A stack of asymmetrical horn mouth flares, such as a 1 wide, 3 high pile of LABhorns
Sadly my to-do list gets bigger every damn day.
This leaves the third, and most sensible option. One day, someone will do a proper blind test to check that, I’m sure.
please see post #13 in thread https://www.diyaudio.com/community/...-folded-horn-bass-bin-pa.384981/#post-6993310