Why the obsession?
I'd guess that a big part of it is people not really appreciating just how little musical info there is in the bottom octave, because they think that what they're hearing is lower in pitch than it actually is. From posts I've seen over the years, I'd bet that many folks here would guess way low if asked to ID the frequency of a bass sound played for them. But that misimpression may - in one sense - be useful.
The upper half of the next octave (60hz-80hz)is critical to lots of music and speaker specs are misleading. As Bob astutely points out, those anechoic FR graphs manufacturers provide do not usually include distortion numbers - presumably because they'd suck. Also, room effects are wreaking havoc with the signal throughout the bass region.
Bottom line, it's very tough to predict in-room bass performance from manufacturer's specs. It might not be a bad rule of thumb to focus on 20hz to 40hz with the hope that a speaker designed for critical performance in this sub bass region will be better than average in the octave above. No guarantees, but probably not a bad rule of thumb. Personally, I use room corrected subwoofers, but that's a different thread.
As to the gut impact and spacial cues provided by the actual deep bass, I agree that there is something to this, too. Some recordings have significant energy in the 35-40hz range and you will "feel" this in the gut.
The spacial thing is interesting in that info in this range is impossible to localize, so you'd think it wouldn't help with staging, imaging, etc. However, it's easy to see why even very low level info in the 20+hz range MIGHT provide spacial clues. Think of a predator's footfalls - very low level, very low frequency. Very useful to prey if they can use that info to better understand the environment they're in. Obviously speculative on my part, but - at least - not as counterintuitive as it might seem at first.
Just my guess, my experience, and MHO.
I'd guess that a big part of it is people not really appreciating just how little musical info there is in the bottom octave, because they think that what they're hearing is lower in pitch than it actually is. From posts I've seen over the years, I'd bet that many folks here would guess way low if asked to ID the frequency of a bass sound played for them. But that misimpression may - in one sense - be useful.
The upper half of the next octave (60hz-80hz)is critical to lots of music and speaker specs are misleading. As Bob astutely points out, those anechoic FR graphs manufacturers provide do not usually include distortion numbers - presumably because they'd suck. Also, room effects are wreaking havoc with the signal throughout the bass region.
Bottom line, it's very tough to predict in-room bass performance from manufacturer's specs. It might not be a bad rule of thumb to focus on 20hz to 40hz with the hope that a speaker designed for critical performance in this sub bass region will be better than average in the octave above. No guarantees, but probably not a bad rule of thumb. Personally, I use room corrected subwoofers, but that's a different thread.
As to the gut impact and spacial cues provided by the actual deep bass, I agree that there is something to this, too. Some recordings have significant energy in the 35-40hz range and you will "feel" this in the gut.
The spacial thing is interesting in that info in this range is impossible to localize, so you'd think it wouldn't help with staging, imaging, etc. However, it's easy to see why even very low level info in the 20+hz range MIGHT provide spacial clues. Think of a predator's footfalls - very low level, very low frequency. Very useful to prey if they can use that info to better understand the environment they're in. Obviously speculative on my part, but - at least - not as counterintuitive as it might seem at first.
Just my guess, my experience, and MHO.
