From Mr. Geddes in the linked thread "In my setup the room is special, its designed to be a listening room and it has extensive LF damping" so the question is will his theory still work in an undamped room as well as his with "extensive LF damping". SO he has spent the equivalent of a good sub on room treatments, how is this cheaper?
He has also chosen 3 subs using different crossover regions with each sub, this sounds like a pretty extensive DIY project or at the very least a lot of research to get the correct subs so they will play nicely together.
I think the majority of us are just looking to plop something down and have it play smooth with very little effort. An hour or so of level adjusting good subs to achieve smooth bass qualifies for plop down smooth bass.
I will and have always ascertained that multiple subs of the same are not necessary but there will most likely be a draw back or two.
I have tried a set up similar to what he is suggesting with out any more expense to my self. I ran my old sub with my PB13 and I couldn't even tell my old sub was turned on, it couldn't compete with the PB13. I did try the PB13 at 40hz and the cross over on my old sub was set to work from 60hz down and my M80s XO set at 60. I could not hear any difference except what I felt was a lack in the mid bass that my old sub was supposed to be producing even though it was level matched, so Mr. Geddes theory isn't as simple or easy or guarranteed to work with 3 subs you pick up cheap, IMO.
I think that the bigger point is that multiple subs DO smooth out your bass response through out the room and that there are multiple ways of adjusting the subs for the smoothest response.
