AVAA C214

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (i5, 256GB SSD, 40GB RAM, Sonoma 14), 4TB external SSD with Thunderbolt 3, Audirvana Studio, Qobuz Sublime, Singxer SU-6 USB bridge, LHY Audio SW-8 & SW-6 switch, Laiv Audio Harmony and Sonnet Pasithea; Active filter: Lifesaver Audio Gradient Box 2; Power amplifiers: Kinki Studio EX-B7 monos & Gold Note monoa on subwoofer; Headamp: Kinki Studio THR-1; Phones: HifiMan Susvara, Meze 109 Pro; Loudspeakers: Qualio IQ [on loan] Cables: Kinki Studio Earth, Furutech; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, 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, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 6 x 8m with open door behind listening seat
2nd system: Source: FiiO R7 into Soundaware D300Ref SD transport to Cen.Grand DSDAC 1.0 Deluxe; Preamp/filter: Lifesaver Audio Gradient Box 2; Amplifier: Kinki Studio EX-M7; Headamp: Cen.Grand Silver Fox Loudspeakers: MonAcoustic SuperMon Mini + Dynaudio S18 sub; Power delivery: Furutech GTO 2D NCF, Akiko Audio Corelli; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~3.5 x 8m
Desktop system: Source: HP Z230 work station Win10/64; USB bridge: Singxer SU-2; DAC: iFi Pro iDSD Signature; Head/speaker amp: Enleum AMP-23R; Speakers: Acelec Model One Headphones: Final D-8000 & Sonorous X, Audeze LCD-XC, Raal-Requisite SR1a on Schiit Jotunheim R
Upstairs headfi system: FiiO R7; Headphones: Meze 109 Pro, Fiio FT3
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: Zu Soul VI; Subwoofer: Zu Submission; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: £3K/ea.

Analog version left, digital version middle and right.

Like a hole in my head. "I need xyz about as much" is how the saying goes. How about a hole in the wall? Don't envisage a rat or termite infestation, human intruders, flooding or other distinct undesirables. Add the word 'virtual'. If we could create a virtual 1½ x 1½ metre hole in the wall behind each of our loudspeakers, we'd depressurize the area. From that we expect reduced room modes and cleaner time domain performance so fewer late-arriving slow-decaying bass reflections. Swiss pro-audio company PSI Audio in conjunction with two local universities have created exactly such a hole-y thing. Its effect claims to be up to 45 x larger than its 64cm x 21cm columnar size of 11.1kg. Its pressure-absorbing bandwidth is 15-160Hz. It needs no calibration. A built-in microphone measures our acoustic conditions in real time. Its digital circuitry is groomed for minimal latency. Its twin 5½" drivers create negative pressure. PSI are quick to stress that theirs isn't a basic anti-phase effect. The device lowers the acoustic impedance of the air fronting it. It's most effective in the room corners behind the speakers. That's where pressurization from playback tends to be highest. Plug in a power cord. Set the depressurizing action's magnitude manually with up/down gain switches; or remotely by free smartphone app.

The PSI Audio AVAA C214—henceforth Eva—purports to seriously shrink the cubic volume of passive bass traps of like effectiveness. Where space and décor considerations outlaw classic passive traps, the far tidier active Swiss invention should slip in rather stealthier. And Eva won't change our direct music signal. It's not in the signal path. Instead it bleeds off follow-on pressures of wavelengths long enough to wrap around our speakers to build up in the front corners. Without explaining the exact 'how' of the invention, calling the 'what' a virtual hole in the wall seems à propos. To experience this black hole sucking in high standing pressures which negatively impact our sound, I had to get in line. Review units were in heavy demand. Yet the company's sales & marketing manager Fabrice Del-Prete located a journeying pair just then staring holes into walls in Hamlet's country. To boom or not to boom? He earmarked the units for an Irish pitstop before moving onto the next demo.

I know of three main ways to tame in-room bass issues. The physically most intrusive is the classic passive bass trap. Completely invisible is digital room correction which notches out response peaks in the amplitude domain. Visible but far smaller than passive traps are super-dipole aka cardioid aka Ripol bass systems. Due to lateral out-of-phase cancellation and asymmetrical front/rear radiation (lower output toward the front wall than listener), such systems shape directional bass. They put far fewer bass energies into a room than typical woofers which below ~200Hz radiate omni. Walls, ceiling and floor now become secondary sound sources. Hello room gain. Each reflection adds time-delayed output. My pick of the three bass problem solvers for the main system has been cardioid radiation. I use no classic acoustic treatments other than the Swiss sound|kaos sub.

That doesn't behave like a typical pressure generator. Instead it's MO is that of a velocity converter. I have a remote bypass switch on my active pure analog hi/lo-pass xover. I have it set to 100Hz/4th-order to cover 35Hz/70Hz modes. Bypass demonstrates the difference from the seat. In full-range speaker mode with omni bass, I hear instant fat room boom. Pear-shaped. In the time domain I hear offensive ringing. Its overhang or drone overlays the lower midband. Whilst digital EQ could surgically cut out response peaks, it can't do zilch about time-domain ringing. Though post-EQ bass will exhibit more linear loudness, it still bounces off all hard boundaries just as it did before. 80% of typical omni bass still continues to arrive at the ear noticeably delayed. This ghosting blur follows an LF transient like exploding dirt accompanies a mortar hit. Eva claims to absorb bass rather than just trim its amplitude so we also expect time domain¹ improvements of superior stoppage. Bass won't linger as much past its recorded sell-by date. What only users of effective traditional bass traps could tell us who additionally must be willing to temporarily remove them all is how close two Eva might come. Can two small active bass traps absorb as much as an array of big passive types? I haven't a clue. In our digs, passive traps big enough to actually work are beyond the pale².
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¹ Corrective software can already improve the time domain performance of our speakers with digital delay. This can for example time-align a vertical baffle's tweeter with its woofer. Equivalent smart bass management can do it for a corner-placed subwoofer with digital latency which additionally sits extra meters from the seat than our speakers. By inputting the distance differential, the software applies the correct time delay to sync up its speaker high-pass with the sub. Such software simply lacks Eva's real-time monitoring via microphone; and its actual absorption rather than just delay effect. The same is true for room correction software which applies strategic attenuation of frequency peaks but can't cause physical absorption of low frequencies to eliminate their reflective time delay.

² This expression dates back to 13th century Ireland to describe people living in parts that were outside British control. Called the Pale, these areas originally were parts of the counties of Meath, Louth, Kildare and Dublin. "Once you passed the Pale, you were beyond the authority and safety of English law so subject to all the savageries of rural Ireland. Beyond the pale thus became a colloquial phrase meaning outside the limits of acceptable behaviour or judgment."