High-end companies like to claim that they create speakers that don’t sound like other audiophile speakers. Usually, such assertions are just talk. But Utah-based Zu Audio breaks almost every rule of speaker design. What’s more, its American-manufactured designs kick ass, and play nice and loud without raising a sweat. And since all Zu models feature a 10.3″ full-range driver that covers bass, mid, and well up into the treble range, they don’t use a complex crossover network. This almost direct-coupled approach yields major sonic dividends in the critical midrange region.

In Zu’s Soul Superfly, the main driver extends slightly beyond 10khz, and is augmented by a supertweeter that uses a Polish-made 1″ composite dome tweeter mounted in a beautifully machined aluminum-flared horn. Most tweeters on two- or three-way designs are crossed over much lower, typically between 1.2—4kHz. Zu’s technique makes for a dramatic difference in the way the speaker puts sound in the room. Boy, does it ever!

Big Brother and Little Brother

The Soul Superfly is a hot-rodded version of the Soul, and the models sport a few key differences. The Soul is internally wired with Zu Mission cables; the Superfly is cabled with Zu’s silver alloy B3. While the Soul uses ERSE Pulse-X audio grade polypropylene capacitors, the Superfly utilizes Mundorf Silver/Oil capacitors inline with the tweeter. The Superfly’s cabinet is internally coated with a layer of QuietCoat Composite paint, with the MDF bonded with a penetrating binder; the Soul is untreated MDF. The Superfly employs a Cardas copper speaker wire clamping connector forged to the internal cable harness; the Soul uses traditional five-way binding posts. The Superfly can be custom ordered in any finish; the Soul is only available in Zu Smooth Matte black.

A Modest-Sized Speaker, Served Best with Tubes

Zu designs are super-efficient, and the Soul Superfly is no different, boasting a very healthy 101dB @ 1 watt spec. So it can rock the house with just a handful of watts. Don’t worry, power handling hasn’t been slighted; this bad boy can handle 300 watts. The Soul Superfly’s 16 ohm impedance favors tube amps, so I used three: the Miniwatt N3 with 3.5 watts per channel; the Jolida FX10 with ten watts per channel; and a Luxman SQ-38u 30-watt integrated. The Superfly’s high impedance also makes for a splendid match with OTL (output transformerless) tube amps from Atma-Sphere, Transcendent Sound, and Futterman. Zu claims that solid-state amps won’t be the best matches with the Soul Superfly, but the company produces a few models that work equally well with solid-state amplification.

As far as space demands are concerned, the Soul Superfly isn’t that big. It measures 38″ high and 12″ square at its base, while the sloping side panels meet at the 9.5″ square top panel. The MDF cabinet feels solid, and the speaker weighs 50 pounds. Build quality is excellent, and the model is available in three standard textured finishes: Chocolate, Cosmic Latte (beige), Cosmic Carbon gray. Zu also offers extraordinary custom-finish options, albeit for a whopping $2,000 extra. The fee is based on 20 extra hours of labor and the cost of expensive paints. But the charge is worth it. That metallic lime green Soul Superfly I spotted at the 2010 Rocky Mountain Audio Fest? Absolutely stunning.

Class Comparisons

Sonically, the Soul Superfly is tonally rich and solid, and possesses a weight that few other speakers anywhere its price range muster. Credit the 10.3″ driver’s air-moving power, dynamic punch, and near full frequency bandwidth for the gravitas. The sound is not as transparent as Magnepan’s spectacular MG 1.7 panel speaker ($1,995/pair) I reviewed in Issue 30, but the 1.7 can’t match the Soul Superfly’s tonal richness. If you want both—transparency and soul—be prepared to drop more dough.

Zu’s Essence is a larger speaker, and utilizes a ribbon tweeter, making for a more refined-sounding experience. Still, I’m partial to ribbon tweeters. The Essence sounds bigger, with more air, resolution, a deeper soundstage, and more bass definition than that of the Soul Superfly, all for a higher price.  The Essence doesn’t even match the Magnepan’s walk-through transparency, but like the 1.7, Zu’s speakers march to a different beat.

The Soul Superfly’s big attraction? The way it unleashes dynamics. You’d be hard pressed to find another box or panel speaker anywhere near the Soul Superfly’s size or price that touches it. In this sense, the speaker sounds more like a horn speaker, but without the usual horn (cupped-hand) colorations.

Amplifiers As Soul Food

I never thought Philip Glass’ music had a wit of soul until I played it on these speakers. I liked the idea of Glass’ music, but it often sounded cold, mechanical, and uninviting. The Soul Superfly changed my longstanding opinion once I played Glass’ Glasspieces LP. Whoa. The music’s rhythms and grooves had me going, big time. The Soul somehow uncorked more of the music than I’d heard before. This was material that, after all, was once performed by living, breathing players, and it’s the hi-fi’s job to bring them back to life. The Soul did just that.

Early 1970s Columbia LPs tend to sound thin and hard, but that wasn’t the case with Al Kooper’s I Stand Alone when played through the Luxman SQ-38u integrated amp. The record’s strings and brass, bathed in reverb, were a treat, and Kooper’s elastic vocals seemed more humanly present than I’d previously experienced. The Soul Superfly projected a large soundstage, with fairly sharp focus. Not bad for an LP purchased for 99 cents at Princeton Record Exchange.

Switching amps, the Jolida FX10 did a fine job goosing the Soul Superfly into action with the Black Keys’ raunchy blues. The duo’s latest, Brothers, is a low-down romp, with massively distorted guitar and pummeling drums, and is best enjoyed with the volume cranked way up. The FX10 obliged, though the Luxman coaxed even more grunt from the mix. In addition, the Luxman delivered considerably more meat on the bones, but the FX10’s sound was immensely satisfying on its own. Brothers sports the best batch of tunes from any Black Keys album, and the Soul Superfly only increased my love for the record.

The designation of the tubiest-sounding amp in the listening chain fell to the Miniwatt N3, a single-ended design that utilizes a single ECC83 twin-triode tube feeding one EL84 output tube per channel. The N3 delivered a healthy 3.5 watts per channel to the Superflys, and they loved it. Sure, it looked almost comical: A teensy 5.25″ wide and 6″ deep amp next to the Souls. But those 3.5 watts were sweet and clear, with a truly gorgeous midrange and pleasantly full bass. Tone color and dimensionality were absolutely yummy, and textures came through with utmost transparency. The Miniwatt N2 sells for just $378, but I could happily live with it and the Soul Superfly.

As might be expected, the Luxman SQ-38u integrated tube amp (review in the works) proved the best overall mate with the Soul Superfly, yielding more holographic imaging and a very un-hi-fi, yet totally musically convincing sound. Instruments sounded more natural, and after three different amplifiers, I became convinced that the Soul Superfly was designed for tubes. Why? There’s a rightness to the sound that my solid-state amps can’t match. Bass doesn’t go subwoofer deep, but it’s generously proportioned.

The solid-state Pass Labs XA100.5 monoblock amps exerted a profound sense of control over the Soul Superfly, the sort of difference that could be definitely felt when a drummer really whacked his kit. The big solid-state monoblocks offered more slam and dynamic contrast, but the overall tonal balance shifted to the cooler side. While this never appeared mechanical or harsh, it was easier to forget about the gear when I had a tube amplifier in the chain.

Blow Out the Candles

Zu just celebrated its 10^th anniversary in 2010, and it seems like the company has only begun what will be a long run. The Soul and Soul Superfly are the latest additions to a promising product line and should be perfect fits for those with low-to-moderate-powered tube amplifiers that want something out of the ordinary.

Zu Audio Soul Superfly

MSRP: $2,600 a pair

www.zuaudio.com

Peripherals