D12/PW

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (i5, 256GB SSD, 40GB RAM, Tahoe 26), 4TB external SSD with Thunderbolt 3, Audirvana Studio, Qobuz Sublime, Gustard U26 USB bridge, LHY Audio SW-8 & SW-6 switch, Sonnet Pasithea; Preamp: Hattor Audio ARP-S; Active filter: spl Audio Crossover MkII; Power amplifiers: Vinshine/Kinki Dazzle & Audiophonics NCx500 on subwoofer; Loudspeakers: Qualio IQ [on loan]; Subwoofer: sound|kaos D15; Cables: Exact Express Flame, Furutech; Power delivery: 2 x Kinki/Vinshine Tai Hang on amps and source stack, Furutech DPS-4.1 between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc amp stands; Sundry accessories: Acoustic System resonators, AudioQuest FogLifters; Room: 6 x 8m with open door behind listening seat; Room treatment: 2 x PSI Audio AVAA C214 active bass traps
1st upstairs speaker system: Source: Shanling EM7 into Soundaware D300Ref SD transport to Cen.Grand DSDAC 1.0 Deluxe with POW; Preamp/filter: Lifesaver Audio iCon 4SE & Gradient Box 2; Amplifier: Kinki Studio EX-B7 monos; Loudspeakers: sound|kaos Vox3awf; Subwoofer: sound|kaos D12 on twin Nord Acoustic NC500 monos; Cable loom: Exact Express Earth; Power delivery: Vibex Granada/Alhambra, Akiko Audio Corelli Corundum & Castello Solo; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Furutech cable lifts, Furutech NFC Clear Lines; Room: ~3.5 x 8m
1st upstairs headfi system: DAC: Cen.Grand DSDAC 1.0 Deluxe with POW; Headamp: Cen.Grand Silver Fox; Headphones: Raal 1995 Magna, HifiMan Susvara
Desktop system: Source: HP Z2 workstation Win11/64; USB isolator: LHY UIP; LAN distributors: LHY AS6 Pro & SW6-SFP; Ethernet reclocker: Stack SmoothLAN; DACs: Gustard R26II & Audalytic DR70; Preamp: Topping A900; Speaker amps: Topping B200 monos; Headphone amp: Enleum AMP-23R; Loudspeakers: Virtual Hifi Viper; Headphones: Final D-8000, aune SR7000, FiiO FT7, HifiMan Susvara Unveiled
2nd upstairs headfi system: Shanling EM5; Headphones: Meze 109 Pro, Fiio FT3, HifiMan HE1000 Unveiled
2nd upstairs speaker system: Source: smsl PL200T CD transport; DAC: Shanling EM7 w. 1TB microSD; Crossover: Lifesaver Audio Gradient Box II;  Amplifiers: LAIV Crescendo Chorus monos; Loudspeakers: MonAcoustic SuperMon Mini with Dynaudio S18 subwoofer
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: ModalAkustik MusikBoxx; Subwoofer: 2 x Zu Mission; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: €5'350 in stacked Ply as shown, €5'900 with mono XO¹, €6'260 with dual-mono XO²

The insert shows the very similar construction of my D15 just with a wooden plinth.

Truth and dare. Tell the truth. Face the consequences. Skip 'or'. Today though, nothing is heroic. No speaking truth to power to risk incarceration; or worse. Just a lustful consequence of having experienced the Vox5. It had been most memorable. Saying so in the award-ending review told the truth—on how <150Hz folded-dipole bass could generate low loud bass of feline agility and superior damping without riding the room modes of my 4m narrow space or pressurizing it. I could finally do bombast at happy hour without causing the room to revolt. After years of owning the bigger D15 RiPol sound|kaos sub in my main system, I understood the MO. I'd simply never had it on my upper floor. That 2×15" sub weighs more than I can stairlift. With the Vox5 loaners earmarked for a Swiss reunion with their maker, my dream was to expire soon. Enter desire to replicate it with something I already had: its companion Vox3awf monitors. Rather than run them wide open augmented by a sealed Zu Method sub for some 1st-octave assist at 40Hz/4th–order, I'd high-pass them at ~120Hz. Martin Gateley's smaller 2×12" D12 would now treat the lower 2½ octaves to far more directional far less room-interactive dispersion. I ordered my D12 with four banana inputs. Each woofer would see its own mono amp. The sub's stacked Ply build would duplicate that of my bigger downstairs version. Instead of white Corian end plates, my D12 would have the alternate clear-finished aluminium plates shown above.

Still fuzzy on RiPol or folded-dipole¹ bass? See the drawing. Being wired in push/push, two face-on woofers apply maximum stoppage on each other. Their combined front wave exits through the single slot aimed at our seat. The equally quickly stopped back waves exit through two rear slots. At the wavelengths involved, anti-phase energy wraps around the box. It cancels at the sides in classic figure-8 dipole style. This eliminates sidewall reflections and their lateral standing wave. Unlike panel dipoles whose front/rear moving surfaces face our room for zero loading, this folded geometry first patented by Axel Ridthaler—hence RiPol for Ridthaler dipole—slot-loads its woofers. This has twin benefits. One, it lowers their resonant frequency by up to an octave vs. the same driver in a classic ported box. Two, if the involved math follows the Ridthaler formula, the rear emission is of lower amplitude than the front. Hello directionally shaped bass. It no longer radiates scattershot in all directions to play 3D bass snooker. More aims at us, less is lost to the room. Demonstrably fewer LF reflections clean up the time domain. We have less bass smear from loitering, droning and triggered room resonances. Bass notes stop more punctual. They no longer suffer hangover. Much haphazard room bounce cuts. That turns temporal blur to focus, mud to clarity. More clarity isn't just good for bass. It invariably improves the midrange because now there's less resonant overlay from below.
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¹ As shown in the Vox5 and previously Voxativ Alberich², this type bass system also works with a single woofer; or multiple woofers stacked vertically. Such arrays obviously get a single rear slot not two.

Another benefit—or demerit depending on your take—is RiPol's MO of velocity converter. Standard box bass of the sealed/ported variety generates pressure. If played low and loud enough for a given room, we feel this pressure. Longer exposure to pressure creates fatigue like sealed headfi does when played too long. It loads down our ear drums. With a RiPol sub, we hear far cleaner bass of superior stoppage and linearity—but don't feel it. This type bass won't create the pressure sensation that 99.9% of listeners call normal because they use omni-radiating box bass in untreated rooms. The road tax for folded-dipole propagation is diminished room gain. That's the reflective product of omni bass. Less of it means lower bass efficiency. That needs more cone surface to compensate equivalent loudness and extension. No free dinner. Just so, RiPol bass eliminates pressurized LF. That creates a textural feel far closer to midrange and treble. The gestalt is reminiscent of open-backed headphones which don't suffer typical room issues. Whatever remaining chamber resonances they still exhibit shrink the pathways of bouncing reflections to millimetres or centimetres. Standard speakers and subs deal in multiple metres. That implies greater delays so far more serious time confusion. The truth of my dare were major hots for RiPol bass. Today's silly dare meant naught but an invoice. I can't credibly champion RiPol bass for untreated rooms then continue with standard omni subs. Now two of my systems would walk the talk. As such my 5-year makeover of various 2-channel systems into 2.1 equivalents with actively high-passed mains neared completion. What this latest acquisition enabled is massive attack–type fare in a modestly dimensioned space without bodily discomfort or acoustic mud; somewhat like fitting the proverbial square peg into a round hole. I knew the result a priori. I'd already heard the Vox5 in this very room. The 2×12" sub would simply halve the cone surface; and create RiPol cover in mono not stereo. That's exactly how I already run my main system. I knew what to expect.

What's a dare without any risk? A sure thing.