@mijostyn --
"... sorry lad, it would appear your experience is lacking. I have heard and built Horn subwoofers. Mahlmans’s sense of vibration is not good. I hope he is not diabetic. The other answer would be that his horns do not go very low which is in keeping with his other posts. Yes, horns are very efficient but, bass is bass and it is very powerful and hard to contain. Any subwoofer, horn or otherwise putting out 20 Hz at 85 dB is going to shake and it is going to shake the entire house. Making one that does not vibrate with just the distortion produced by the driver is virtually impossible. There are examples that come close, Magico’s Q subs come to mind. I might be able to do better. We shall see. I have been designing and building subwoofers for almost 40 years."
Forest for the trees, as they say. Not to impugn your decades of experience, I hope they’ve done you some good, but it seems to me you’re chasing an aspect in subwoofer design that’s really the lesser evil compared to, in my mind, more primary goals. You’re a line source guy on the main speaker front, one terminated at both the floor and ceiling no less, so why haven’t you gone to length ensuring two bass columns, loosening a wee bit on the vibration control, placed in each corner behind the mains to meet the challenges faced here with both headroom and acoustic coupling? No, because you’re hellbent on killing vibrations as that which has precedence, thus limiting yourself to a smaller sub design. It’s all a matter of degree and measuring its importance relative to other aspects, and to you vibration/resonance control comes first with all that entails - fair enough. I’d have gone differently, as you imagine, letting physics more readily have their say - vibrations to some degree be damned.
@mahlman’s horn subs (yes, in my understanding of the correct use of the word ’sub’ they qualify, being they’re able to reach honest 30Hz without any issues) as a classic single-fold front loaded horn, very high efficiency at that, will most likely deliver some of the most effortless, smooth and nuanced bass out there. I’m sure there’re some cabinet vibrations at elevated levels, but do they really matter in the bigger scheme of things, not least outweighed by the qualities of a horn sub design that has the woofer cone moving close to zilch at anything but earsplitting levels sans mechanical driver noise, where a direct radiating sub design like yours, almost 20dB’s less sensitive, will necessitate up to 100x the amount of power and prodigious excursion for the same SPL?
Shelling out $40k for a single(!) sealed, 15" loaded Magico sub is just dumb, sorry. That’s $80k for a pair of them, and it’s not like they cured polio or other.
"As for horns being the best type of driver, they have their advantages. I am waiting to hear a horn system that is not colored. They also require crossovers. IMHO the best type of system is a one way driver crossed to a subwoofer below 125 Hz where digital bass management is easy to apply. The only one way driver that is truly one way is an ESL. With horns you are also stuck with a point source system. It does not matter how big they get. Line sources project power better particularly in the bass and are more capable of generating the visceral sensations of a live concert."
I have no issues with ESL’s, really, other than they need to be big to really be worthwhile (and usually lack macro dynamics), certainly compared to big horn setups. And yes, an advantage of theirs is not needing a cross-over in most of the audio band, except crossing over to a pair of subs and the challenges this presents. Point source(s) as a design characteristics is not necessarily a flawed approach. A single point per channel is desirable and to my ears is most favorably realized through the Tom Danley invented Synergy horns, but they also need to be fairly big to do their best and maintain directivity control down low to the subs. The dispersion characteristics of my horn hybrid main speakers is quite uniform through their audio band, not least at their single cross-over point, and this is achieved via the big midrange/tweeter horn and how it couples to the twin vertically mounted 15" woofers. In that regard they’re sonically not wholly unlike big panel speakers.
