How do Active Wave Focusing filters work?
Active Wave Focusing filters mark a complete departure from the classical crossover filter. Instead of just splitting the spectrum into bands, it forces the specially positioned drive units to create a completely coherent wave front that is only emitted forward and behaves as though all of it came from the midrange driver.
With classical crossover filters, loudspeakers can only have a time aligned impulse response on the main axis. The animations on the right show the wave front as it’s built up by a typical modern three-way speaker with side-firing woofers. This example is crossed over at 250Hz, time aligned and phase equalised. Indeed the wave travelling towards the listener is coherent. Towards the sides and the rear the picture breaks down and the impulse is completely smeared. Also, low frequencies get emitted in all directions. In a real room (bottom animation) the sound that escapes toward the back will strike the wall behind the speaker and reflect towards the listener, who actually hears the speaker twice: once from the front and a bit later from the rear. Moving the speaker out into the room doesn't help. The overall bass balance looks better but the impulse response gets worse as the reflection now comes even later.
The animations on the right side of the GIFs show how the Active Wave Focusing method retains full time alignment all around the speaker and how the presence of the rear wall has no impact. Sonically, the effect is a very even, unusually detailed bass. Even in problematic rooms, a drum kick has that visceral thud that previously only very big or in-wall speakers could achieve.