"Hoffman's Iron Law". First formulated back in the early 1960's by Anthony Hoffman (the H in KLH), Hoffman's Iron Law is a mathematical formula that was later refined by Thiele and Small, whose work now forms the basis of all modern loudspeaker design.
Hoffman's Iron Law states that the efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency (the lowest frequency it can usefully reproduce). The obvious implication is that to reduce the cutoff frequency by a factor of two, e.g. from 40 Hz to 20 Hz, while still retaining the same system efficiency, you need to increase the enclosure volume by 23=8 times! In other words, to reproduce ever lower frequencies at the same output level you need an extremely large box! This is why we see so many subwoofers or low eff multidriver towers. Using 5-7 in drivers. Larger woofers are better woofers, larger cabinets are more efficient and produce deeper bass with less thermo compression and Superior transient response. If one compromises size efficiency or range one can make a smaller design.
Hoffman's Iron Law states that the efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency (the lowest frequency it can usefully reproduce). The obvious implication is that to reduce the cutoff frequency by a factor of two, e.g. from 40 Hz to 20 Hz, while still retaining the same system efficiency, you need to increase the enclosure volume by 23=8 times! In other words, to reproduce ever lower frequencies at the same output level you need an extremely large box! This is why we see so many subwoofers or low eff multidriver towers. Using 5-7 in drivers. Larger woofers are better woofers, larger cabinets are more efficient and produce deeper bass with less thermo compression and Superior transient response. If one compromises size efficiency or range one can make a smaller design.