Why the obsession with the lowest octave

There is 40hz bass and then there is 40hz ATC active 100's bass. Real 40hz isn't all that bad.

Elizabeth, LOL and then there was the woman on Jeopardy who was shown a picture of a bird and asked "What is a Booby?" Well if she doesn't know, then who would?

adding on to Dan_ed's post, from what i could figure out the fundamental at 40 Hz has a subharmonic at 20 Hz as well as overtones at 80 /160. it is a combination of all of these which give the flesh/timbre to the tone.
Any graphic equalizer using a digital out (eg i used a DEQ2496) shows a surprising amount of music in the 20-25hz region in many peices. the most surprising revelation has been "GrandMas hands" by Livingston Taylor. supposed to be an Acapella but has a consistent 20-25 hz bass content which is not heard in anything but a fullranger OR with subs and once you hear it that way can never ever listen to it without that bass fabric!

Where are people getting this sub-harmonic talk. Yes, string instruments can produce sub-harmonic sounds, but it is not a commonly used technique and it's virtually never written into compositions. Harmonic overtones are always present in acoustic music, sub-harmonics are not.

"Grandma's Hands" was recorded on a suspended wooden floor which is being excited by the foot tapping of the singers. It's a common effect in recorded gospel music. It's debatable if those sounds are part of the performance or are they in the class of falling mic stands, A/C rush, passing subways, page turning and fret scrapping, in other word noise. Although on tunes like the Supremes "Where Did Our Love Go" the floor effect is prominently featured as part of the rhythm track.

Another thought with a full range speaker is that if the speaker is capable of reproducing extrememly low tones (the same goes for the extreme high tones as well) then the vast majority of music doesn't require the speakers to work at the max capacity. I think this is applicable to just about all audio equipment. You wouldn't want an amplifier to be driven maxed out. This would only apply to a subwoofer in the sense that it can reduce the low frequency requirements on the mains. Having a tweeter than goes well above the audible frequency range just allows a better reproduction in the range that you can hear.

"Having a tweeter than goes well above the audible frequency range just allows a better reproduction in the range that you can hear"

Not necessarily - it might distort more at few kHz range.