There's a lot more bass in a 6.5" driver than most of you think

@erik_squires

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To appreciate what constitutes a good bass, one needs to experience a distributed subs system like the Swarm

Not at all universally agreed to.
https://www.soundandvision.com/content/are-you-putting-subwoofers-behind-viewer "

The author has no idea how distributed bass works. Both Geddes (PhD thesis on bass) and Welti (Floyd Toole’s Harman lab) found in their research that key to distributed bass is asymmetric placement. Geddes believes three sources is enough: one in the corner, two others haphazardly against other walls. Duke LeJeune, Geddes’s coworker and constructor of the Swarm, adds the fourth source. There is no point adding more sources. Phase switching is not really part of the concept. Digital corrections of the whole system can be applied, but already the haphazard placement does most of the job. Digital corrections using counterwaves, such as those used in Kii3 or D&D, don’t really work below 50-60 Hertz. To battle complex phenomena like room modes, randomness is the most optimal way. Here, one can see easily, what problem room modes can be computationally:
hunecke.de | Room Eigenmodes Calculator

One more interesting concept is dipole bass, proposed by Siegfried Linkwitz in his  LX521. The subs are v-frame dipoles and the side wall modes are minimized by cancellations. The bass is incredibly clear and tight.
Finally, one can put the single sub next to his listening position to get at least one good spot with it.

In your post regarding Linkwitz you prove my point. The idea that only swarms can produce great bass is what I object to.

Hello pirad,

    I was so impressed with your knowledge and posts on this thread, that I looked at your profile and read many of your previous posts on a wide variety of other threads and subjects. They were equally impressive, demonstrating an equally substantial knowledge of the science of the subjects combined with an obvious good measure of practical experience on the wide variety of subjects.  
    I'm fairly certain my very high opinion of your posts as very high quality are influenced by the fact that I agree with the vast majority of your well worded opinions. I was just curious whether you're associated with an audio industry company or just an interested consumer hobbyist?

Thanks,
  Tim

I have built both dipole and distributed bass systems. Dipoles are great for any kind of music down to the bass guitar low E (40Hz). Under 30Hz the experience is not impressive. The Swarm, when sealed, goes down to 18Hz. With the ports open even lower, but it gets kind of boomy. The sound is powerful but not so clear and natural as from dipole bass. I would say if classics, pop and jazz are your thing, go for dipoles. If you are a basshead or need to shake your home theater, distrubuted sealed boxes will deliver.
PS. I should add that if you can hear sounds under 20Hz, you are likely to be an elephant. The human experience under 20Hz is rather vibration permeating various body parts. If you play test sounds under 20Hz and insist you hear them, then something is wrong with your subs. They play harmonics where they shouldn’t be. This test actually shows faults in the construction. Try these tests:
The Ultimate Bass Test | Ultra Low Frequency Range Test