Slow Bass

From our late May 2021 feedback section. "Srajan, surely you must be aware that with two 15-inch drivers, pretty much any other sub would go a lot lower and far louder than that esoteric Swiss box you're covering. Why would anyone settle for a design that throws away so much output? That's nuts if you ask me." Rainer

I hadn't asked but okay. "Hmm. As always I will trust the intelligence and reading comprehension of my audience. Precisely because of this very effective dispersion pattern and its lateral cancellation, such designs avoid reflecting off the side walls by creating directional bass. Even front-wall reflections are smaller than they'd be with box bass. Less room involvement does mean far lower room gain, correct. But it also means fewer room problems and bass that doesn't ricochet all over the place before it arrives at your ears. If you don't get that, I'm afraid I can't explain it better. It's really a very simple equation. You get faster bass because late-arriving reflective bass is slow bass. Faster bass means superior timing so better articulation. The price to pay is throwing away more than 50% of the generated output. No cancellation, no directional benefits. You might not consider that a fair trade. Fair enough. Having heard it for myself, I very much do. Different stripes and all that." Srajan

Bass oh bass, when will you let go and show up?

"Directional bass is BS. Bass travels in all directions. Anyone except you knows that. Slow bass is BS too. All frequencies travel at the same speed. You really swallowed that Cool Aid, didn't you?" Rainer

"Actually, sound travels at ~3ms/m. Say your box woofer sat 3 meters from you. Its direct sound will hit you in 9ms. But sound that reflects off the ceiling will easily add another 3 meters so arrive in 18ms or 9ms later. Depending on your room dimensions, diagonal reflections could take even longer. So your time window of bass arrivals is quite broad. Those portions which travel the farthest will arrive the most late. Last time I checked, late equaled slow and when mixed up with earlier, imprecise. What should be one sharply defined event gets smudged and dragged out over time. If you think directional bass so much holy cow dung, talk to Bruno Putzeys about his Kii 3 and its cardioid dispersion. It does the same. And it works. Anyone who heard one (including me) can attest to that. So yes, this Cool Aid is filled with enzymes and vitamins. Try it. None of it refutes your arguments that bass travels in all directions; or that all wavelengths travel at the same speed. You're just confused about how those basic statements happily coexist with counter-phase cancellation and reflective time delays. That's all." Srajan

"Whatever. If that subwoofer concept was so superior, why don't we see it all over the place? There's clearly something wrong with it." Rainer

"The concept used to be patented so was protected. Now the patent expired and others can revisit the basic idea and perhaps even improve upon it. If majority rules defined excellence, we'd never have things like the Raal SR1a ribbon headphone. It's the only one of its kind. It's not alone because there's something wrong with it. It's so alone because nobody else could figure out how to do it properly. Things are just a little bit more complex than you make them out. And now let's do something more fun than argue about hifi. Enjoy your box sub and never mind those who do it differently. It's clearly not for you." Srajan

The asymmetrical front/rear output of the sound|kaos RiPol sub.

This exchange contained basic but worthwhile information. So I syndicate it here with its own feature. Slow bass is no myth. Bass drag comes from contrasting frequencies which, as they rise, narrow in dispersion to generate fewer reflections. Fewer reflections mean more direct arrivals and fewer late ones. With typical box speakers, we're used to this discrepancy of time arrivals, between low and mid/high frequencies. Slower bass signal (far more reflected than direct) delivers together with faster mid/high signal (more direct than reflected). Though an imbalance, that's our status quo. It's our familiar normal. Our full-fat bass preferences depend on it. An initially lean-sounding alternative is a full-range panel speaker like a Magnepan or Soundlab. Their type too cancels ± phase at the panel edges. That too puts proportionally less bass into the room. That too avoids the reflective side-wall delays which the omni dispersion of box bass causes.

So lovers of dipole bass celebrate its quickness and precision. They have a need for speed. Lovers of box bass criticize it for being lean and lacking oomph and slam. Box bass lovers prioritize slam and mass.

Who is right? Whoever gets more enjoyment from their system.

The 'folded open baffle' enclosure of a RiPol sub, in this case the stacked Ply construction of the sound|kaos.

Slow bass isn't about lazy heavy woofers being out of sync with aspirated light tweeters. Slow bass is about late arrivals which dominate the direct sound to blur it. The bigger the room, the longer its reflective pathways. Those longer sonic travels delay the late bits more. It's why many speaker designers sweat time alignment. They want to insure that at least the direct sound lines up in time across multiple drivers. It's why pre/pros and DSP xovers in subwoofers can include user-selectable delays for their high-pass signal. This compensates for time-misaligned setups, say when a corner subwoofer sits farther from the seat than the speakers to create late bass. Delay the speakers by the necessary amount and all syncs up again. This compensates for DSP latency in the sub as well. It's all done to insure that at least all of the direct sound components arrive at the ear at the same time regardless of frequencies. About reflections, speaker and subwoofer designers can't really do anything. Dealing with room acoustics is down to us; except for very clever designs like the Kii 3 which apply heavy DSP and deliberate phase cancellations for directional bass; and RiPol subs which do it purely acoustically.

Either way, less confusion in the time domain means a clearer listening experience that's easier for our ear/brain to understand. That's the meaning of slow bass and how to temporally de-blur it without DSP or MQA. This de-blurring applies an analog high-pass filter to remove low/mid bass from the main speakers. Then it routes that signal to a RiPol sub whose deliberate acoustic short circuit at its sides eliminates usual room reflections which are always late. Less late is more on time. It's not about perfection of zero time delays. It's about fewer time delays so relative gains in clarity. Those come from shifting the direct/reflected bass balance more deeply into its direct part. That's it.

A few speakers by Bastanis, Ecobox and Voxativ include RiPol woofers. Everyone else looks to separate RiPol subs. I reviewed and awarded Germany's ModalAkustik MusicBass. The sound|kaos is the only pending alternative I know of. Unlike Rainer, I'm just not convinced that this rarity signals anything amiss with the concept. Au contraire. But in the end, you'll be the judge. If it's really rare, must it be wrong by design because everyone else does it different?