Reviewer: Srajan Ebaen
Financial interests: click here
Sources: 27" iMac with 5K Retina display, 4GHz quad-core engine with 4.4GHz turbo boost, 3TB Fusion Drive, 16GB SDRAM, OSX Yosemite, PureMusic 3.01, Tidal & Qobuz lossless streaming, COS Engineering D1, AURALiC Vega, Aqua Hifi La Scala MkII, Fore Audio DAISy 1, Apple iPod Classic 160GB (AIFF), Astell& Kern AK100 modified by Red Wine Audio, Cambridge Audio iD100, Pro-Ject Dock Box S Digital, Pure i20, Questyle QP1R
Preamplifier: Nagra Jazz, Esoteric C-03, Vinnie Rossi LIO (AVC module), COS Engineering D1
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1, F5, F6, F7; S.A.Lab Blackbird SE; Crayon Audio CFA-1.2; Goldmund Job 225; Gato Audio DIA-250; Aura Note Premier; Wyred4Sound mINT; AURALiC Merak [on loan]
Loudspeakers: Albedo Audio Aptica; EnigmAcoustics Mythology 1; Sounddeco Sigma 2; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Submission; German Physiks HRS-120; Eversound Essence
Cables: Complete loom of Zu Event; KingRex uArt, Zu and LightHarmonic LightSpeed double-header USB cables; Tombo Trøn S/PDIF; van den Hul AES/EBU; AudioQuest Diamond glass-fibre Toslink; Arkana Research XLR/RCA and speaker cables [on loan]; Sablon Audio Petit Corona power cords [on loan], Black Cat Cable Lupo
Power delivery: Vibex Granada/Alhambra on all components, 5m cords to amp/s + sub
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands [on loan]
Sundry accessories: Acoustic System resonators
Room: Rectangular 5.5 x 15 metres with two-storey gabled ceiling and stone-over-concrete flooring
Review component retail in Europe [ex VAT]: €9'990/Fostex, €12'990/Lowther, €14'990/Voxativ, €2'000/pr Oris 500 horns, €940/pr gold-plated WBT terminals, €40/pr wooden phase plugs (Fostex only), €700/pr Marble floor plates

In the castle of Lešná village in the Vsetín District, northwest of Valašské Meziříčí.

Into upscale bottles, are you? Cheers. Then the Czech Republic—or Czechia, not Chechnya if the country's recent name change application gets approved—will already be pinned to your hifi map with a cherry-red heart; for EAT, Emission Labs and KR Audio valves which are produced there on equipment dating back to the old Tesla factory. Now you also might want to know about RDacoustic's widebanders. After all, they're a type of high-sensitivity transducer very often favoured with especially low-power direct-heated triode amps. That's very different from the speakers Xavian build in the same country. At the end of March, Jiri Maler introduced me to their company with a request to review the above Evolution speaker. If to you that looks like a less angular cousin to Voxativ's Ampeggio, you wouldn't be frivolous. Not only does it indeed (having reviewed and owned the Ampeggio, I can say so), amongst the drivers Jiri & team can fit into their folded rear-horn cab are Voxativ. And Lowther. And Fostex. They can even front-horn load them into a short 500Hz Oris turned from solid oak. "We have great feedback from independent reviewers and audio lovers throughout the Czech Republic. Because we're thinking bigger, we now need a review from your magazine." The map below shows their location within Europe; and then where within the small 17'000 strong town of Rožnov pod Radhoštěm they make their home. That's some 20 kilometres from the Slovakian border where JJ Electronics manufacture more tubes; and amplifiers to use them in. Do we detect strong support for vintage hifi from this region of Europe?

Before learning more about the Evolution from the horn's mouth as it were, I inspected their published photos; plus one rendering of the guts. That showed a single smooth bend in the constantly expanding rear horn. It also showed a lateral cylindrical cavity behind the driver. It isolates its short run of hookup wiring from air turbulence inside the line. As a consequence, the terminals on their bronze plates mount next to the driver on the side wall. Orientation inside or out is up to the client. Regardless, it necessitates an unsightly connection of speaker cables halfway up the speaker. It speaks to the perennial conflict between aesthetics and sonic purity. Where exactly will detractors begin to invoke hair-shirt itch? I took note also of what appeared to be quality automotive lacquers Voxativ-style; fat bulbous trim rings around the drivers; and an attractive leather baffle treatment. Endemic to single-driver widebanders is an absence of electrical filters. What you see is what you get. That short list is the enclosure; the often very expensive driver; the binding posts; and some wire in-between. The purist religion of such minimalism must address response aberrations in - well, the purely mechanical domain. That means geometry of the horn line—how many folds and facets exactly where along its length, flare rate between throat and mouth—strategic selection on metalurgy for hookup wiring and terminal posts alike (silver, copper, other); and physical tweaks to the driver. The inevitable upshot? On the test bench, such speakers never measure as steady as conventional boxes with their compensation networks and notch filters. Many in fact measure outright bad.

Whether claimed advantages of widebander propaganda like point-source dispersion, freedom from filter effects and high efficiency outweigh typical liabilities of limited bandwidth, a tendency for a rising ragged response above 3kHz and uneven dynamic response falling off seriously in the bass - that is the lynch pin and routine contention. Frequency response mapping of rear-horn geometries vs. driver parameters hasn't yet made real inroads into advanced predictive modeling software as it has for ported box designs. This type design thus relies on more than its fair share of cabinet prototyping than mainstream speaker houses would tolerate. That and generally poor measurements are key why single-driver speakers tend to come from small boutique operations. It further reinforces why in general, little computer modelling is brought to bear on them. To write ground-up software programs demands specialized know-how. Whilst not impossible—Albedo Audio of Italy wrote their own to model transmission-line loading more accurately than existing software did—it's not something to expect from the cottage industry. Far more common is the iterative prototype approach based on, here we go again, pure listening. Call it a more artisanal than laboratory gestation period. Or call it trusting your ears over measurements.

For driver tweaks, RDacoustic strategize with different wooden phase-plug tapers and lengths; and the optional front horn which simply slips onto elongated bolt heads. For the 25mm thick and 70kg heavy 180x50x50cm Evolution cab, they offer an even taller 2.2-metre version. Between those variables and the many different driver options—96dB Fostex 206EN is standard—the Evolution is quite a moving target. I was thus keen to know how its maker sorts out which version best suits a given customer. At contact time, their English website pages were still very much incomplete. I couldn't make out whether their Czech pages already covered that topic. Not that it'd mean much. The plan was for me to review their Munich HighEnd 2016 show samples. They'd be extensively broken in. That's major for such often very slowly blossoming drivers.