Kepler's upshot aims high not low. It's clearly built to an unusually high standard then very competitively priced by a small operator who needn't support a big staff in a large building rented in an industrial park. By keeping its inner workings hidden, Kepler's full MO remains mysterious. We do know that applying a quad under a speaker rests it across the micro points of synthetic sapphires whose hardness is second only to diamonds. How the transmission path of input vibrations completes remains protected IP. It's easy to confirm that it works; and without the jittery wobble of moving ball bearings in shallow races. On my desk, prior experiments involved thick steel supports with an added layer of trapped sand; thick hard-rubber footers repurposed from a set of mono amps; assorted pointy cone footers with receiver discs; and more. None of it got the tempered glass plate as quiet as Kepler. Whether anything exists that could equal absolutely zero transmission I don't know. It certainly won't cost what Kepler does. It'll probably be something like an active Minus K platform otherwise used under electron microscopes. Shy of hifi extremism and within its 20kg/ea. weight rating, Divine Acoustics' astronomically named but not priced Kepler footers could well be the thing to beat. I'm glad that I learnt of their existence; and that its maker proved amenable to lend me a few sets to play with.
I've deliberately not touched upon their use under gear since my racks handle that already. But apply common sense. The vibrations of poorly isolated power transformers, discharging capacitors or spinning hard drives/discs are dwarfed by the energies which long-throw woofers release into the air; and under even higher pressures sink into their cabinetry. Whilst today's devices can't address airborne energy transfer, they certainly work most directly on the jackhammer action that sets up between pumping speaker pistons and the floor that supports them. If you can't acknowledge very real potential for sonic improvements once tended to, your leetle grey cells may have checked out. When they check back in, think again. Now remember Kepler. As Johannes, the man knew things before the rest of us caught on. As Kepler the footer, he too knows things many of us haven't considered yet. Once those lights come on, act upon what they tell you. That's especially true for subwoofers. Friends don't let friends drive subs without structural isolation in place. As it stands, Kepler kicked butt on my upstairs sub install. At least that set will have to stay. And so it goes whenever hifi nutters chance upon more effective solutions. Step by step we tweak our systems to reveal more of what's recorded whilst reducing negative interactions between our gear, utility power and room. It's a never-ending story with many chapters and footnotes. For me, Kepler just flipped another page.
The end; for today. Or so I thought. Then David Masilamoni's email arrived. "Have you ever had a listening room with suspended wood floor? Did you need to do anything to damp the floor of sympathetic resonances? I feel I'm losing bass because of a suspended wooden floor."
"Yes; but not exactly as you may think. It's not that I damp the floor. I simply prevent the gear, speakers and sub from sinking energies into it. That relies on decouplers so the opposite of spikes. We want to disrupt the transmission of mechanical resonances into the floor where they amplify and propagate. Coupling a subwoofer to a floor is no different than coupling a subwoofer to the chassis of a boom truck. The boom-truck owner looks to maximize bass output so he uses his car like a giant resonator. A piano does the same with its soundboard. So do guitars and violins by coupling their strings to resonant tone wood. Replace a piano soundboard with concrete or plastic and watch the sound die. If we take away the floor as a structural resonator—and suspended upstairs wood floors are excellent resonators—we delete its SPL contributions.
"That's like room gain. Each reflective surface adds output to the signal. Effective bass traps reduce SPL/output/power but increase clarity. Like reflections, resonances are always late. They happen after the original/direct event. Late means delayed. If direct signal is followed by delayed signal, the result is a blur in time. The sharp thin line drawn by a hard tip becomes a smudged thick line with ambiguous edges. Isolating speakers and subwoofers from the floor so they can't talk to it and it doesn't talk back improves time-domain behavior. That benefits clarity, definition and intelligibility. But it also removes some structural gain. If you've looked at anechoic speaker measurements, you saw how invariably, their response dropped sharply below 100Hz. That's because all speaker designers count on room gain to add itself to their response. If that were flat in an anechoic chamber, it'd get seriously bass heavy in actual rooms. The same applies to isolation. You gain speed, precision and transparency but give up some time-delayed resonant output.
The five stones beneath the M10 bolt head (three for the M6) sit atop the steel plate. From Piotr's shop pix, we earlier saw another array of three bigger stones beneath the steel plate for double-decker action.
"With an active bass system, you could compensate if desired. With passive bass you can't unless in software EQ. So if you say that you're losing bass because of a suspended wooden floor, I'd say yes and no. You're definitely losing timing precision and pitch definition because the floor gets involved and talks back; but you also gain some free output for the very same reason. It's quantity or quality."
Obviously Kepler is about quality, not any artificial but unpredictable boost of low frequencies via structure-born gain from resonant floors and walls. Unlike a piano's soundboard, our room isn't a musical instrument. Just like speaker cabs, we don't want it to sing/ring along more than it does with boundary reflections already. With Kepler, speaker and subwoofer isolation isn't about wobbly platforms. There are no moving parts. Kepler's low profile duplicates many spikes and stock footers. Especially when it screws into a threaded receiver like an ordinary spike, it won't cause undesirable elevation changes. This is a cleverly engineered well-executed solution for a very particular job. Adding noise to our music signal is distortion. Rattling air vents are distortion. So are resonances which travel through the floor and add themselves to the sound. If they migrate into adjacent rooms or apartments, they devolve into irresponsible noise pollution. Why go there if an antidote exists which is neither highway robbery nor looks like Geek Central? So get up out of the lazy bed on the right foot(er). The end.