Over the years of reading subwoofer tests by Tom Nousaine and others, it appears that a sub capable of hitting 105 dBs that Nousaine would have raved about 10 years ago would now be described by him as having only average or even "limited" output.
That is because subwoofers have significantly improved over the past decade. An "average" decent subwoofer today is better than an "average" decent subwoofer of 10 years ago. So to stand out, it must be better than before.
The same situation, by the way, has occurred with other things. For example, cars are more reliable by far than they were 30 years ago. A car that was of average reliability 30 years ago would be dreadful by today's standards, and one from today of average reliability would be fantastic compared with the reliability of cars 30 years ago. So the standard for a "reliable car" has changed over the years.
I don't usually watch movies at superloud levels and I must confess to wondering this: If a sub was hitting 105 or 110 dB peaks, what would the sound pressure level be across the rest of the spectrum handled by the other speakers?
There is no telling what level the rest of the sound will be when the bass is at 105 or 110 dB. Assuming that you have set your system to give a flat response, it will depend upon what else is in the mix, and how loud the other sound was mixed relative to the bass.
Surely no one could stand to watch a movie for long at those levels.
Since you previously said "105 or 110 dB
peaks" [emphasis added], that is probably not for long, unless the sound has little dynamic range and is constantly at or near the peaks.
Isn't 90 dB bass at 30 or 40 Hertz at the listening position plenty LOUD enough for the average person who cares about preserving his or her hearing? Just curious...
No, it isn't tremendously loud, as your hearing isn't nearly as sensitive near the low frequency limit of hearing as your hearing is to midrange (nor is it as sensitive at the high frequency limits of hearing). And loud very deep bass does not damage hearing at the same level as loud midrange and treble. And 90 dB, though loud for a constant level of midrange, is not terribly loud for the occasional peak.
Also, the measured output in a review will not necessarily tell you what level it would be in your room. Generally speaking, if you have a large room, to reproduce deep bass accurately, you need a subwoofer that would, in a small or medium sized room, be able to output prodigious amounts of bass.
And, if you are interested in all of the bass possible, as loud as it will be in normal situations, you will need a really good subwoofer to reproduce the lowest notes of a pipe organ. If you have ever heard such notes played loudly in a church or auditorium, you have felt your whole body vibrate. It is a bit like the way some earthquakes feel, and it takes a really good subwoofer to do that decently. This, by the way, is also relevant to the issue of proper balance. If your subwoofer is not flat down to 16 Hz, you cannot have a proper balance for the lowest note on a pipe organ. It should be able to reproduce 16 Hz, without audible distortion, as loud as you ever wish to play music with the lowest note on a pipe organ. Few subwoofers are up to playing such a note properly.
In the past, when playing music with an organ playing deep bass, I wanted to turn up the bass in order to have that vibration that should be felt on such occasions. That, however, meant an overemphasis on upper bass, not a flat response down to the lowest notes. But since I now have a pair of SVS CS-Ultra subwoofers set to give me a basically flat frequency response, I get that feeling without adjusting the bass control, thus having everything in its proper proportion and balance.
