PDU

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 monos on subwoofer; Headamp: Kinki Studio THR-1, Enleum AMP-23R, aune S17Pro Evo; Phones: Raal 1995 Immanis; Loudspeakers: Qualio IQ [on loan] Cables: Kinki Studio Fire, Furutech; Power delivery: Kinki/Vinshine Tai Hang on amps, Furutech GTO 2D NCF on low-level gear; 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; Room treatment: 2 x PSI Audio AVAA C214 active bass traps
2nd system: Source: FiiO R7 into Soundaware D300Ref SD transport to COS Engineering D1 DAC/pre; Filter: Lifesaver Audio Gradient Box 2; Amplifier: Kinki Studio EX-M7; Headamp: Cen.Grand Silver Fox; Loudspeakers: MonAcoustic SuperMon Mini + Dynaudio S18 sub, sound|kaos Vox 3awf, Albedo Aptica; Power delivery: Vibex Granada/Alhambra, 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 Z2 work station Win10/64; USB bridge: Singxer SU-2; DAC: iFi Pro iDSD Signature; Speakers: DMAX P61; Headphones: Final D-8000 & aune SR7000 Audeze LCD-XC
Upstairs headfi system: FiiO R7; Headphones: Meze 109 Pro, Fiio FT3, Raal 1995 Magna, HiFiMan Susvara
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: $997

Display shows voltage, current, power and energy. 20A IEC on the back.

The tip. "At the just concluded Hifi Deluxe show, we had a visit by Vladimir Kraz of OnFilter Inc. who kindly supplied us with one of his CleanSweep AC EMI filters to try. We did a short comparison with our Puritan unit and found very much the same results. What particularly interested me was the inclusion of circuit breaker tech rather than the usual fuse or MOV options. Vladimir is keen to enter the audio market as up to now he concentrated on other sectors. He asked if I could arrange an introduction to 6moons for a possible review. If there is interest from your side, please contact Vladimir directly." This was signed Martin Gateley of sound|kaos. So I followed up. [At right, resettable 15A circuit breaker on rear of EMI filter.]

"Thank you for your email. First a short preface. For already 15 years, my company OnFilter based in Santa Cruz/CA has been manufacturing EMI filters for many facets of industry like factories, R&D labs in all major US universities and in Europe, quantum computing, hospitals, military and aerospace including NASA, nuclear power plants and more. We focus not on budget but performance. This is why our filters are used in the most demanding applications. All our products are made in the US then shipped to all seven continents, Antarctica included. A few years ago we began to receive orders for our EMI filters from audiophiles. We first considered it a mere curiosity but sales grew and audiophiles seem to like our CleanSweep filters. You can see unsolicited feedback here.

"Now it is the fastest-growing though very far from biggest segment of our business. We would like to serve this market well and seek advice, recommendations and reviews from experts. This market is very different from our core industrial and scientific clients. The two products audiophiles buy the most are our AF series CleanSweep filters and filtered PDU, the latter based on the AF model. Both offer hard specification which is a must in the industrial world, high-level EMI suppression in real-life environments and uniquely, EMI filtering not just in common and differential mode but also in ground while meeting safety regulations."

"While we guarantee EMI suppression performance (see short videos here), we claim no sound improvement effects. Those we cannot quantify hence such claims would be superficial and imaginary at best. Many audiophiles who care to communicate back to us apparently do note sound improvements. Again, the main purpose of our EMI filters is to just filter EMI and provide your hifi with clean power. Unlike transformers, our filters do offer low output impedance by design. We have a newsletter on that subject in our library. They also offer non-sacrificial zero-wear transient surge protection. Please look at this one. To summarize, I would love to get your expert opinion on the performance of our AC EMI filters. We can ship for evaluation either an AF series filter or a PDU. The latter presently only comes with US outlets." That's how all my power delivery past the UK wall sockets rolls. So I opted to tell this story with a 6-outlet power distribution unit. Arriving from the industrial sector and confirmed by the above photos, there'd be no bling or overkill chassis but optional rack ears server-farm style. Just like Martin referenced in his cross intro, this did remind me a lot of the UK's very no-nonsense Puritan Audio Labs replete with 20A high-current IEC. Would OnFilter's PDU be on target for domestic hifi consumption? Our sector has numerous successful crossovers from pro audio and industry. Examples of the latter are the Minus K platforms meant for electron microscopes. Many isolation footers borrow from industrial solutions. Audio's high end works with endless parts sourced from IT. Kaiser Acoustic's lead speaker engineer also works in the automotive sector on silencing engine compartments. These are soft borders with plenty of cross pollination. Very soft is our sector's subjectivity which overlays and mostly dominates the discussion. Whilst measurements can confirm a unit's compliance with published specs, most hifi buyers decide on sonic preference. That might show zero correlation with measured performance.

OnFilter arrive from industry where hard specification rules. Dealing with rampant subjectivity could seem confusing even annoying. Yet Vladmir Kraz was keen to not only poke that bear but tame it. So here we are. That said, Puritan Audio Labs have successfully stuck to their industrial style. There's built-in potential for OnFilter's focus with those sick of High-End hifi's inflationary excess and dubious claims. A reviewer now segues straight into our subjective sphere: does OnFilter's EMI-filter tech have sonic benefits? We'd hope that their non-sacrificial surge protection works as advertised. But even if I could mock up a lightning strike on demand, I'd not risk frying my expensive work tools. Our prior home in Cyprus once got struck. Because the landlord/builder had installed over-spec'd circuit breakers, they clamped down fast enough. The only appliance victims were the telephones and answering machine whose line was unprotected. Yet my ears rang for days. Not again. Even car reviewers leave crash tests to the manufacturers and government agencies.