In defence of The Cult of the Infinitely Baffled and the True Infinite Baffle Subwoofer:
Russell has obviously become confused by all his recent cabinetry glue sniffing.
While I am much older and wiser, and probably borderline senile, I can still remember the first "infinite baffle loudpeakers" from first hand experience.
True Infinite Baffle subwoofers are very large closed boxes. Usually they are so large that they don't even need to be well sealed. Room sized boxes of 600 cubic feet, or 17 cubic metres, are the normal
minimum volume required. Their (enormous) advantage is that you can happily live a completely normal life right
inside the enclosure. No boxes are needed in the AV room and no sound absorption in the enclosure.
The ideal True IB subwoofer uses the entire Earth's atmosphere as its enclosure. Because there is really no need for an IB to have any box at all. It is merely a convenience in a domestic setting to stop the opposite phase, rear (rarefaction) waves from reaching and cancelling the front (positive) pressure waves at the edge of the (theoretically infinite) baffle. Using a room for the enclosure/cabinet contains the bass emanating from the rear of the driver/loudspeaker unit. Both front and rear of the driver cones reproduce sound in equal quantity but of opposite phase.
Unfortunately the term "infinite baffle" was hijacked by the loudspeaker industry in a desperate bid to sell dirt cheap and simple, sealed boxes at very high retail prices to a gullible and completely ignorant general public. A public who were just beginning to discover they were not really affluent enough to afford the new High Fidelity equipment following years of rationing after the Second World War. This was prior to teenagers receiving a living wage. So this potentially vast market had yet to be tapped.
Giving these new, little, sealed boxes a pseudo-scientific name was supposed to overcame their complete lack of bass and desperate shortage of Xmax to go loud and low simultaneously. Should I also mention their horribly coloured sound quality? I know, because I was there.
Ironically, the new little sealed boxes required a completely different type of loudspeaker/driver to the former reflex and open-backed, resistive cabinets commonly used up to this time. Loudspeakers in the home were normally used in open backed radios and radiograms with a perforated hardboard back to protect the public from lethal voltages. Pioneering High Fidelity Enthusiasts built brick reflex cabinets or concrete exponential horns in the corners of their drawing rooms.
Unfortunately the high compression of the air inside the new small sealed box, by inward cone movements, forced up the natural resonant frequency of the cone on its suspension. This robbed the little sealed boxes of the deep bass enjoyed by all those who used the reflex (ported) principle. Something had to be done!
One could overcome this lack of bass with a much heavier cone or much floppier suspension. Or both. Prior to this, loudspeaker units had corrugated rims to their cones to act as suspension for the bare few millimetres of movement they could manage. The new, small, sealed boxes needed much greater cone movement if they were to reproduce useful bass. So the roll surround suspension was born. This half round, foam edge allowed the cone to move much further. Though this also required completely new thinking about voice coil and motor design. The new loudspeaker units/drivers began to evolve away from the conservative designs of the past into the large, floppy units we see today. Now only PA drivers tend to follow the Old Ways of corrugated surrounds, small Xmax and high Fs.
Competitive SPL drag racing and car audio have given driver evolution even greater impetus towards cheap, large, fairly floppy drivers with tremendous displacement thanks to long, linear cone movement. (Xmax = one way useful travel) Without all of these incremental developments, subwoofers, as we know them today, would not exist.
The True Infinite Baffle Subwoofer uses several, large, floppy drivers with very low self resonance (Fs below 20Hz) and completely avoids loading the cones with back pressure to provide a smooth, linear output to below 10Hz. IB's are renowned for their low distortion and lack of compression. They have become the subwoofer of choice for those who have a suitable spare room, attic or cellar off the AV room. Since True IB subwoofers are so affordable, relative to many commercial subwoofers, price does not usually enter into their choice. Very few commercial subwoofers can compete with a True Infinite Baffle. None can compete at anywhere near the installed price of a common four x 15" driver, True Infinite Baffle Subwoofer.