The IB Array
My first attempt at a True Infinite Baffle Subwoofer proved to be slightly flawed. It performed incredibly well compared with my large commercial SVS cylindrical subwoofer. It was just that the array seemed to lack the giant-killing power that I had read about in posts from other delighted IB subwoofer owners on The Cult of the Infinitely Baffled. (A specialist Internet forum dedicated to True Infinite Baffle Subwoofers)
The major problem was the flexibility of my baffle wall. This old planked-over-vertical-studs wall forms part of an even older timber-framed house with later additions. When the four big 15" driver cones moved ... the wall moved the opposite way! Newton's Law of action = reaction was biting back with a vengeance.
The original array had a remarkable performance but had shaken the wall and adjacent double doors far too much for comfort. In fact the whole house seemed to shake from the mechanical vibration of the drivers. The bass sometimes made me feel nauseous in the bathroom below the IB enclosure! Yet despite the available power and four large drivers the output on programme material was just a little disappointing. It failed to vibrate the floor on films no matter how much I played with BFD filters. Despite an easy 120+dB capability and 8Hz extension on test tones the IB just did not deliver quite as expected. I also had absolutely no headroom to play the subwoofer louder ("hotter") than the speakers on programme material. Something had to be done!