Frequency Response?


If a speaker is rated down to a given frequency response (say 40 hz), wouldn't that suggest that 40 hz is about as low as the given driver is capable of reproducing, not accounting for roll off? When taking roll off into concideration, will the driver continue to attempt to reproduce frequencies infinately below the given 40 hz, or is there a point that it is just incapible so it doesn't? What I am asking is, Will a driver designed and constructed to play down to 40 hz even attempt to reproduce a 20 hz signal? I want answers!
62bakes
Thanks for all the great answers. I have another question. Since the driver continues to try to reproduce these lower frequences, does it do any harm to the driver sonically or physically?
Frequency respone specifications are often so generalized that they have very limited value.

Some mags like stereophile will do more comprehensive actual measurements of fr and others. Those are more useful in terms of measuring actual performance.

For the average joe, a reference test cd or record to generate test tones at various frequencies and your ears as the measuring device can be insightful. Or a spl level meter device can be used.

Of course music is a much more complex signal to reproduce than any test tone, but a suite of variable test tones can gjve at least some degree of quantifiable measurement of how you system and your ears perform.
Yes there is harm done. It uses a lot of the amps power to reproduce
what it can at the lower frequency which can negatively affect the rest of
the music and leads to clipping distortions at lower volume than
otherwise.
Does anybody produce a QUALITY high pass filter that can be inserted between the pre and the amp without compromising signal quality? Don't trust the networks installed in subwoffers. To many external influences on original signal.
62bakes - One way they increase extension of the speaker is to put second woofer for the lowest bass only (higher frequencies filtered out by xover). For two way speakers it is called 2 1/2 way speaker (pretty much like adding subwoofer). I suspect that small drivers, being point source, will have more interaction with the room than large woofers where bigger percentage of the sound goes direct.

Distortion might be caused by by nonlinearity of the motor especially at max extension of the membrane. Most of drivers are designed as overhanged type where magnetic gap is narrow but coil is long extending outside of the gap. Some drivers (like in Acoustic Zen Adagio) have underhung motor meaning that gap is very wide and the whole (narrow) coil is inside of the gap. This scheme is more linear but requires drivers with very large magnets - more expensive. Some tweeters are made that way as well (to lower distortion at max power) including Morel Supreme.