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This review first appeared in the January 2009 issue of fairaudio.de and can be read in its original German version here. It is herewith translated and presented to an English-only audience through a mutual syndication arrangement. As is customary for our own reviews, the writer's signature at review's end has a link below it to his e-mail should you have questions or feedback you wish to send. All images contained in this review are the property of fairaudio.de or PHIO. - Ed.


Reviewer: Ralph Werner
Sources: Analog - deck - Acoustic Solid MPX; tone arms - Phonotools Vivid-Two, SME M2 12-inch; carts - Denon DL-103, Ortofon MC Rondo Bronce, Zu Audio DL-103; digital - player - audiolab 8000CD; Computer & Co - Logitech Squeezebox, Readynas Duo NAS-Server, HP Notebook; D/A converters - Aqvox USB2DA-MKII, Benchmark DAC1 USB
Amplification: Phono - Aqvox 2 CI MKII; preamp - Octave HP 300 MK2; power amp - SAC il piccolo monos; integrated - Lua 4040C, Myryad MXI 2080, Octave V 80, Cary SLI-80 [on review]
Loudspeakers: AudiaZ ETA, Sehring 703, Zu Audio Druid mk4 and Presence
Racks & Stands: Creactiv, Taoc, Liedtke Metalldesign Stand, Shale Audio Base
Cables: diverse
Review component retail: €9.600/pr
Reviewing can be a gas. No sooner did my last tower speaker get worked up -- well, Zu Audio's Presence was far more pleasure than work -- than the next one moved in. Beyond price however, little else proved similar. PHIO Audio's two-way Signature is cut from different wood. Or rather, poured from stone. Duisburg is what its firm and chief bottle washer Carsten Wendt call home. Certain DIYers will be familiar with the brand as Herr Wendt has offered diverse speaker kits for years. But his catalogue also includes component supports with matching footers and a pickup body for the Denon 103 mod scene. Today though is about turnkey speakers, specifically the middle bass module and small tweeter horn of his 'Signature kit'. That's actually the first lesson here. There's no fixed product hierarchy at PHIO but rather, an interchangeable system of three bass bins and two high-frequency horns which offer various combination options.
While choices will be somewhat informed by money, the greater determinants are the listener's space and taste. Naturally, prices do vary. PHIO's speaker offering begins at €8.800 and tops out at €12.200. More expensive needn't equal superior (always true but openly admitted by the maker for once) but, in certain cases, could make the better fit. Or not. For my requirements, the aforementioned €9.600 combo was the ticket. PHIO's modular approach recalls Berlin speaker house Sehring's. It's a very rationale but (accordingly?) rare solution. The Wendt transducers' signature ingredient is artificial stone. It makes up the horn modules
exclusively and also shows up for the baffle and top of the bass units. Not apparent to the eye is the fact that depending on where one looks, one deals with "different stones". Herr Wendt prefers to mix up diverse materials and not just composites. On what he thinks of MDF, the answer is "like salt". Things get boring without any but to concoct an entire meal around salt wouldn't occur to him.

Tech
With the Signature, this pinch o' MDF salt appears with the back and bottom panels of the bass box. While still around back, you'll discover a bass port and, above the terminals, a rotary pot which can alter the sensitivity above 400Hz up to the crossover point of 1200Hz from 90 to 88 and 86dB while the low bass value remains fixed at 90. A prospective customer thus retains adaptive choices well beyond bass 'n' room aka module options. And there's something else on the back too, something ultra solid if no aesthetic revelation - 16 screws. If you've kept count and figured on MDF for the side walls, you'd be dead wrong. They're Ply. Internal cross braces run solid or pressed wood. Reliance on four different woods for the box indicates a focus on resonance minimization rather than elimination, the latter impossible in the first place. Remaining resonances are meant to spread out broadly and mimic the behavior of real musical instruments to become less noticeable. This also goes for the use of different synthetics. Their advantage over real stone, contingent naturally on know-how and production capabilities, is that the precise composition of artificial stone can be adapted far more specifically to the intended application. The baffle and top of PHIO's Signature are thus constructed in layers. The driver first is bolted to the wooden baffle which then gets covered by a structurally fine composite layer before the coarser core material of greater mineral content is applied. The outer skin then is once again the finer material. PHIO reports that baffle assembly takes 10 days (which naturally includes intermediate drying cycles).

The bass module's top must provide decoupling of the horn from LF pulse interference. Thus this panel benefits from the third specific stone mixture and the fourth one pours into the horn itself where its composition is optimized to apply damping over its operative band. By definition, this particular material no longer merits the 'stone' descriptor despite appearing as such to the touch. As per Wendt, it no longer contains any mineral particles whatsoever and is a complete synthetic compound. Besides the material composition of the enclosures and their resonance-attenuating properties, the horn itself is of course the second signature trait of this speaker. It kicks in relatively soon, at 1,200Hz as stated earlier. Due to their lack of surface area which leads to excessive excursion, that's too low for most tweeters and negatively impacts their distortion values. Why high-pass so early then?

According to Herr Wendt, the advantage is in avoiding the critical 2,000 - 4.000Hz octave where human hearing enjoys its greatest amplitude sensitivity. That's a good idea in theory but less so in practice if it means higher distortion figures. But wait, that's where the frequency-dependent amplification action of the spherical horn comes in. At lower frequencies, its gain is higher. It peaks at ca. 2kHz with around +12dB, then diminishes to zero around 8kHz above which the horn no longer contributes any acoustical gain whatsoever. The necessary trick then depends on properly counteracting the horn's gain bell curve with the high-pass filter for a composite linear response. The key point simply is that at lower frequencies, the horn gain reduces excursion demands on the tweeter and thus also reduces distortion. To be clear then, PHIO employs its horns primarily as anti-distortion devices rather than sensitivity accelerators. That latter value is adjustable in 2dB steps between 90 and 84dB. But there's an additional rocker switch on the back of the horn which allows for an optional 2dB cut above 10kHz. That'll be inaudible for most but, as per Wendt, is occasionally advantageous to disarm an "overly digital" CD player. Aha.

As mentioned already, PHIO offers two different horns. The smaller one is for small to mid-size rooms and moderate SPLS; the bigger one's higher output potential makes it more suitable for larger rooms and louder volumes. The smaller horn costs €4.800/pr, the larger one adds 800 euros. The drivers are off the rack but from upscale vendors. The 8-inch woofer is Eton issue and employs their honey-comb 'Hexacone' sandwich construction plus a heat pipe instead of dust cap to increase thermal venting of the voice coil. The tweeter is an inverted Thiel/Accuton ceramic unit also employed by Mårten Design, Avalon or AudiaZ. Without surcharge, PHIO offers numerous finish options including all available automotive lacquers and various veneers. The somewhat conservative trim of our tester thus isn't the last word in chic despite, as per Wendt, being the most popular finish since its Nextel skin is more impervious than high-gloss lacquers. Many folks will respond happily to the friendly dimensions of this speaker. Our test combo didn't exceed one meter in height including spikes and horn. Even those opting for the biggest Signature duo [above right] won't receive a Goliath. That one is merely 3cm taller and 4cm wider.