Better than webpage or whitepaper, I can explain the important basics right here. There is more to reproducing low frequencies than just a large driver in a large box. A woofer/driver has certain electrical and mechanical characteristics derived from its moving mass, magnet flux strength, coil impedance, suspension linearity and native compliance, diaphragmn displacement, inductance and several other characteristics. Years ago, two researchers set out and mapped how these interact with each other to form the basis we use today to model and make modern bass enclosures. The driver has a natural mechanical resonance frequency, a note at which it moves the easiest and requires the least input power to produce movement. This frequency also tends to be near the lowest frequency that the driver will realistically produce, although there are a few exceptions. The Qts is the relationship between mechanical and electrical characteristics and total compliance of the driver. A low Qts driver can, with the correct combination of other factors, produce prodigious bass in a small or sealed enclosure compared to a high Qts woofer, which will be more linear in a horn or transmissionline cabinet. A specialized 6.5" woofer can extend deeper than an 18" woofer if the T&S parameters are idealized for the application. There are other factors but that is the readers digest version.
EQ can attenuate very low frequencies to reduce driver diaphragmn movement while accenuating bass just above this region to allow for good extention without out of control distortion.
