Hello music bass versus home-theater bass. Except for the biggest of church organs, acoustic instruments don't breach infrasonics. A piano's lowest note is A0 at 27.5Hz. A 5-string upright can hit B0 at 31Hz. The open low E on a bass guitar is 41Hz. A kick drum can make 50Hz. Synth bass can go lower but few producers of music intended for home playback deliberately record data which nobody can hear. They'll assume a practical/theoretical limit of 20Hz. Movie soundtracks mastered for commercial cinemas anticipate different hardware. That poses far greater challenges when relocated to the home and the type speaker one typically finds there. It's why home-theater fans call subwoofers mandatory. It's not just about raw extension but coupling it to full power. With music where nothing explodes, drills into permafrost or launches rockets into outer space, that's no requirement. The primary benefits of a properly filtered sub/sat system for music are expanded dynamic range in general; more bass extension particularly with smaller mains; audibility of the occasional synthesized very low bass; and audibility of spatial effects which may occur at very low SPL but also very low frequencies.

An active music sub has more advantages. It dedicates a sufficiently powerful amplifier of extreme damping to just bass reproduction, then drives its woofer actively so amp output couples to woofer voice coil without interceding parts. That means superior control. The same bass amplifier might behave overdamped, dry and harmonically lean if it had to drive the main speakers for their full bandwidth. As a dedicated bass amp, it can and probably should be picked for pure beast mode. That needn't cost much. Enter OEM class D. Particularly when subs are designed to be filtered below 80Hz or lower still, their woofer/s can turn into a very different type driver than is appropriate for a 2-way where a woofer doubles as midrange to meet a tweeter. Even a three-way's dedicated woofer may need to cover more bandwidth than is ideal to become optimized for true low bass excellence. And it'll be passively driven by an amplifier selected for full-bandwidth sonics, not isolated bass muscle and braking power.

Then there's a sub's ability to adjust bass volume separate from mains volume to adapt to room and taste; and being placed separately from the mains. Unlike dipole/Ripol subs, standard box woofers develop their highest output in a room corner which reduces their excursion which reduces distortion. Corners are hardly ever where main speakers end up. So active low bass by way of an enclosure dedicated to just the first or first and second octave becomes a specialized solution that's optimized for one particular task. By comparison, passive speakers with low-bass pretensions are multi-taskers. Having to be good at everything, they'll rarely be as good at just bass like a superior active sub. That's simple logic. Integrating a sub has always been the real challenge. Enter the Gradient Box. Re: specialized weaponry, Ascendo's note shows how below our specialized music sub, there exists yet another category of infrabass generator. It mandates yet another type of hyper-specialized driver and still far more power to drive it. That's simply beyond my interest and software.

In the off-chance that you imagined a typo—about Ascendo's 24" woofer being their smallest infra-bass generator—clap eyes on their SMSG50 next to their SMSG15. Those numbers mean inches. Hello 50-inch woofer with 34.5cm voice coil and 3.5cm linear excursion, then 6'000W of power to do 5Hz at max output of 105dB and 20Hz at 125dB. That's actual weaponry. And yes, it's as tall as a man and weighs 400kg.


Like I said, not my bailiwick. Yet one must give madness props where due. We just saw a current analog crossover from Wilson. Alex Ridtahler's discontinued in early 2021 due to sudden unavailability of key components. Aesthetix have a 1st-order variable high pass between 40-200Hz built into their Atlas amplifier, anticipating a 6dB/oct. sub like a Vandersteen. Linn's various Exact Boxes and TotalDAC's D2Core use digital filters instead. Regardless, especially owners of passive subwoofers without any electronics inside their boxes—consider this fantastic ModalAkustik MusikBass—will need a quality filter. They should welcome newcomers to this very sparsely populated product category with great anticipation.