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Reviewer: Paul Candy
Source: Cairn Fog v2.0 24/192 CD player, Stello CDT200 transport [in for review], Pro-Ject 2 Xperience turntable w/ Nagoaka MP30 cartridge [in for review], Pro-Ject 1 Xpression turntable w/AT95E cartridge
Preamp/Integrated: Manley Labs Stingray, Audio Zone AMP-1, Stello DP200 DAC/preamp [in for review], Pro-Ject Tube Box phono stage, Graham Slee Era Gold MkV [in for review]
Amp: Stello M200 monoblocks [in for review]
Speakers: Meadowlark Kestrel 2, Living Voice Auditorium [in for review]
Cables: DH Labs Air Matrix and Revelation interconnects, DH Labs Q10 speaker cable, Chord Odyssey biwire speaker cable [on loan], Audience Maestro interconnects, speaker cables and powerChord AC cables, GutWire Power Clef 2 AC cable
Stands: Premier three-tier, filled with sand
Powerline conditioning: Blue Circle BC86 MkII Power Line Pillow, GutWire MaxCon
Sundry accessories: Pro-Ject Speed Box, Pro-Ject Speed Box SE [in for review] Gingko Audio Cloud 11 platform, Grand Prix Audio APEX footers, Walker Audio SST contact enhancer, Audience Auric Illuminator MkII, GutWire Notepads and SoundPads, Duende Criatura Tube Rings, AudioPrism Isobearings, dedicated AC line with Isoclean ICP-002 outlet, homebrew acoustic treatments
Room size: 13' x 17' x 8'
Review Component Retail: $2,295/pr


"There is no spoon." You might recall that line from the now classic Sci-Fi film The Matrix. In this scene, Neo meets the Oracle to find answers to questions we all ask: Who am I? Where am I going? Why am I here? While waiting, he is transfixed by a boy's ability to bend one spoon after another by merely gazing at them. The boy's comment illustrates to Neo that to achieve awareness and to control the Matrix, he has to recognize that there really isn't a spoon present at all. My experience with the Green Mountain Audio Callistos reminded me of that film. They really weren't there either. Until his awakening, Neo had been living in a world that certainly seemed real but deep down inside he felt "a splinter in his mind". Neo knew something wasn't quite right. He suspected there was more to his existence than he could sense. It turned out that indeed there was. Everything he had experienced up to that point was a brilliantly conceived machine-manufactured illusion.


My experience with loudspeakers has been eerily similar. Until I heard the Meadowlark Kestrel 2, I had been living a lie like everyone else and fully believed time and phase coherence were not important or even audible. While most audiophiles seem content to live in this artificial reality of incoherent loudspeakers, I knew deep down that something wasn't quite right so I gleefully swallowed the red pill and followed Alice down the rabbit hole. The Kestrel might have been the little red pill that initially woke me up but the Callisto was Morpheus who showed me just how deep the rabbit hole went. By now, you have no doubt sussed that this will be a rave review. You've sussed correctly. Read on.


The first time I learned of Roy Johnson and time/phase coherent loudspeakers was through an article he wrote several years ago in the Canadian AV periodical, Audio Ideas Guide. I must have read it a dozen times and even today, I am not sure if I completely understand the science behind the concepts. But then again, it took several years of research for Roy to understand it too so I don't feel so bad. Roy is one of a small number of loudspeaker designers who believe preservation of the original waveform is essential for realistic music playback. This is achieved by employing a minimalist 1st order crossover and by physically aligning drivers so that signals reach your ears simultaneously and not staggered in time as in all flat-baffle speaker designs. While I was quite prepared to go into time/phase coherence in detail, our editor covered this very subject in his recent review of the Green Mountain Audio Continuum 3 flagship model. Frankly, I cannot add anything to what Srajan wrote, thus I suggest you read his article. Instead, I shall attempt to explain what I hear with coherent loudspeakers. At the end of this review, Roy Johnson will offer his own insights on the subject.


The first thing I notice with time/phase coherent speakers is a relaxing, open ease that allows for continuous long-term fatigue-free listening. Instruments and voices are far more believable not just in timbre but in size and location. Singers are not nine feet tall and six feet wide. Cymbals do not all of a sudden leap in front of the singer. Nor does a solo violin slide back and forth and side to side as it climbs through its register. Sharp transient attacks such as are produced by a struck piano key or fingers striking a tabla sound far more real. Guitars, violins, voices, and percussion -- you name it -- all display a sense of rightness. While difficult to describe, you will know it when you hear it. With coherent loudspeakers, your brain has less need for subliminal signal processing to convert those time and phase-scrambled notes into something resembling music. Thus, you can hear farther and certainly longer into the music without growing bored, annoyed or tired. Personally, I no longer can live with any other type of speaker. Sure, I can appreciate and even recommend a few non-coherent speakers but to live wit them? No way. Having said that, I have obviously painted myself into a very tight corner and have no doubt drastically limited the number of speakers I can review. However, that's okay.


The majority of loudspeaker designers believe time/phase coherence is relatively unimportant or even inaudible. I am not surprised. First, many loudspeaker firms do not understand the math nor are they inclined to learn it. They are reluctant to go down the time/coherent route because such designs require more robust and expensive drivers. Cabinet construction is more difficult due to the requirement for physical driver staggering. Crossover implementation also requires additional effort. As for reviewers and audio review publications, why would they want to alienate 99% of the loudspeaker industry and potentially affect ad revenue by claiming a preference for time/phase coherent designs?


If a reviewer stated a preference for proper preservation of the waveform in loudspeakers, this should obviously limit future loudspeaker reviews or surely cause loss of credibility. And we all know reviewers must maintain a steady stream of gear to play with, don't we? Frankly, the only loudspeakers that now interest me at all are time/phase coherent designs and single driver designs for mostly similar reasons. However, single driver loudspeakers are not necessarily time-coherent, as you will discover in Roy Johnson's interview at the end of this review. I honestly believe coherent speakers do a far superior job in reproducing the thrills'n'spills as well as the ebb and flow of the music. Just about everything else sounds artificial and contrived to me. Once you know what to look for, you may get addicted like I have and refuse to settle for anything less.


For me, loudspeakers are the most difficult component to shop for let alone review. They tend to distort music to a far greater extent than any CD player, amp or preamp. It can take me several hours if not days to bypass a speaker's character to get at the music. Most incoherent speakers, especially those complex high-order crossover designs that worship at the altar of the NRC, utterly fail to offer me any emotional connection with the music. Instead, they trigger a prevailing sense that what I am hearing is not quite right. They may sound great but that ain't music. When I listen to music for fun and stimulation, I do not hear smooth frequency and dispersion graphs. I hear beats, notes, interpretations, rhythm, and skill or lack thereof. Other than for review purposes, who listens for colorations or midrange suckouts?


Each pair of Callistos ships in three boxes. Two contain the speakers, the third holds the real wood trimmed bases. You would think a speaker constructed of cast marble would appear cold and utilitarian but the Callistos were quite attractive and pleasing to the eye with their soft curves and rounded edges. In fact, they resemble giant thumbs. My wife -- who could write her own review of the Callistos -- also thought they were quite attractive and noted their thumb-like appearance. The cabinets are constructed of Q-Stone, a composite material containing fine marble dust suspended in proprietary polymers. According to Roy, this results in extremely high rigidity and very low ringing. Q is an engineering term to describe a material's tendency to vibrate or ring. Therefore, Q-Stone has a very low Q or ringing point. This was evident by just tapping the enclosure.


The Callistos were extremely inert. The enclosure's shape was mathematically designed to limit cabinet reflections and improve dispersion. This is not unlike the B2 Spirit stealth bomber. Its unique shape and cover paint reflect probing radar beams away from the direction of the emitting platform thus evading detection. Like the Callistos, this careful shaping also makes the B2 difficult to photograph. Twin ports are located on the underside and fire down onto the contoured supporting base. This prevents resonances between base and cabinet bottom. Unlike just about every bass-reflex speaker available, the port tubes are cast marble instead of plastic pipe.


The Callisto sports an Aurasound-built 6-inch paper/carbon-fiber cone with ultra-linear suspension, vented underhung Kapton voice coil and a shielded, radially magnetized neodymium-iron-boron magnet. The tweeter, sourced from Morel, is a 28mm polymer-coated linen dome with a large rear chamber. The unit is encased in a cast marble chamber and mechanically damped. The crossover is, of course, a 1st order design electrically and acoustically and consists of a Sonicap film capacitor and Solen Litz inductor. The crossover point is 2850Hz.


Claimed sensitivity is 90-91dB and impedance is 4.1 to 5.3 Ohms from 100Hz to 20kHz. Cited phase shift is a remarkably low +/- 2 degrees from 200Hz to 8kHz. The Callisto is 20 inches high, 8.75 inches wide and 11.5 inches in diameter while attached to the base. Due to Q-Stone's density, the Callistos weigh in at a considerable 56 lbs. GMA recommends 24-inch high stands. The outer finish is a black Texture-Kote. Several hardwoods are available for the front and rear trim of the Callisto's bases including Bubinga, Cocobolo, Cherry, quilted Maple, Bolivian Rosewood and African Ribbon Mahogany. Speaker cable connection is via a pair of binding posts on the rear of the cabinet.


The grill is soft foam and can be removed and reinserted with the included popsicle sticks. However, Roy designed the Callistos to sound best with the grills in place and you will want to keep them on not just for sonics but also for aesthetics. Without the grills, the Callistos are hardly attractive. Not owning suitable stands, I borrowed a pair courtesy of Mike and Rickey at Ovation Audio in Aurora/Ontario. My sturdy Custom Design loaners were mass-loaded with a proprietary filler material appropriately called Inert.