But only if they have the same motor. Long-throw sub-woofer motors have xmax exceeding 20mm one-way; while 6-8" woofers often go only 5mm so it can be more like one 15" sub matches the output of 24 6" woofers.
Absolutely agree...big is better! big is beautiful! Queen were right about fat bottomed speakers making the rockin' world go round! Although extremely long throw (overhung)designs often use small diameter but lengthy voice coils (increase EMF)..... in these designs you quickly get heat and thermal compression issues from voice coil heating up...you may also run into linear Xmax issues (many designers do not clarify what they mean by Xmax - is it VC geometry of is "linear operating range to within 10% field strength") so you may win in one aspect (extreme excursion) but may lose some SPL capability due to thermal compression and added harmonic distortion (due to lack of linearity). The only thing that always makes sense is the absolutely biggest most powerful honking magnets you can lay your hands on (increases EMF with no downsides but expensive).
Sure, although you can equalize that back to flat in the frequency domain.
Yes you can and I agree that this can work very well, however , I tend to think it is best to avoid exciting strong modes in the first place....because we are then talking long reverb issues. So it may be ok to EQ it out in terms of an extended test signal to get flat response but then what about short lived transients that hang around in the room? Just a thought.
Anyway, we have barely begun to penetrate the subject of big box ultra LF subwoofers on this thread...some people have DIY designed tube towers that run all the way to the ceiling and produce tremendous ultra LF.