The low E on a four string bass guitar (the lowest note it can play) is about 41 Hz, but this is not the frequency you actually hear. You hear the harmonic (82Hz). Your brain fills in the gap. Psychoacoustics.
On a five-string bass, the low B is 31 Hz but you hear 62. Or, more likely, 124.
This phenomenon is so thoroughly understood that if you just google something like "low E frequency" or "low B frequency," You'll get plenty of hits that barely discuss the frequencies of 41 and 31, or not at all.
Chocaholic correctly reports that when we go through the gyrations of actually producing these frequencies, it is not to hear them so much as to feel them. Pressurize the room, he correctly reports. In a live band performance, where serious wattage and speaker/cabinet equipment is used to emphasize these 'subsonic' frequencies, then there is another problem you will encounter. Often, and especially where these frequencies are most emphasized, you get this boomy, wolly, sound-pressurey thing that distorts the rest of the music, and you also get hot and dead spots throughout the room. In my bands, if a sub will be used, it will only slightly enhance those subsonic frequencies. But then...those are not disco bands. Even in the country bands, with all those low frequencies in modern country music, subwoofers are not important. In my view.
Chest-thumping sound is an interesting experience, but it's not how music actually sounds. Unless, as others have mentioned, you are trying to reproduce the sound of a live pipe organ. Good luck with that.
And, as at least one other has mentioned, if these subsonic frequencies are the goal, then you will need to feed a lot of current into low-efficiency 3, 4 and five-way speakers. Some folks like this and are willing to try to balance and smooth out those different frequency band systems (tweeter, at least one mid, woofer and sub). My preference is for the (to my ear) more smooth and delicate high-efficiency speakers.