June 2010

Cardas Audio Clear Interconnects and Clear Beyond Speaker Cables

Cable. Wire. Largely an afterthought to hi-fi enthusiasts through the 1970s, interconnects and speaker cables are now generally recognized as fundamental components of a high-performance audio system. Pioneers who helped define the modern audio cable include Ray Kimber of Kimber Kable, Bill Low of AudioQuest, Bruce Brisson of first Monster and then MIT, and George Cardas of Cardas Audio. When first contemplating how to advance audio cables, Kimber, Low, and Brisson had similar vantage points -- the music and hi-fi industries. By contrast, George Cardas’s career had been with the telephone company, where he was responsible for solving problems in transmission lines.

Cardas Audio, too, contrasts with most cable makers. While many companies design and market the cables they sell, and quite a few assemble their final products, Cardas is unique in actually working the metals (i.e., draws the wire) and connectors themselves. Because of the wide-ranging capability made possible by such vertical integration, the bulk of Cardas’s business is as an original equipment manufacturer (OEM): providing copper and silver conductors to other cable makers; supplying internal wiring, binding posts, and connectors to electronics and speaker manufacturers; and even making specialized materials for scientific research. All of this, and the economies of scale, allow Cardas to maintain a high-value position in a segment of the audio industry often criticized for stratospheric prices uncorrelated with underlying materials cost.

Cardas debuted its new Clear line of cables at the 2009 Consumer Electronics Show. I spoke with George Cardas for more than 30 minutes as he explained the advancements in metallurgy, geometry, and connectors that have culminated in the Clears. A down-to-earth and humble scientist-inventor, Cardas has earned a reputation for being reluctant to sing his or his cables’ praises; he’d rather the results speak for themselves. But in January 2009, Cardas couldn’t contain his enthusiasm -- as animated in discussing the Clears as a beaming father describing his newborn, he was bold in his pronouncements about the new line: “Clear will be my most enduring statement.” I was intrigued to hear what justified such enthusiasm.

No nonsense

In keeping with Cardas Audio’s reputation for no frills, the Clear cables arrived not in an ornamental presentation box or flight case but in a functional tote bag of gray nylon containing heavy-duty ziplock bags, each of these in turn containing a pair of cables and a single page printed in color on card stock, indicating that pair’s type, length, and termination. Each of these inserts also serves as a certificate of authenticity and warranty card, and includes on the reverse George Cardas’s recommendations for optimal speaker placement.

Many cables, especially expensive ones, are finished like audiophile jewelry; not so the Cardases. The rubbery urethane jacket that forms the exterior of every Clear interconnect, USB, and speaker cable is finished in a matte royal blue. The interconnect, which costs $1840 USD per 1m pair single-ended (or $2140 for a 1m balanced pair) is of medium thickness, with a diameter of 0.4" -- slightly thinner than Cardas’s Golden Reference ICs, a well-known design that remains in production but no longer tops the range. Thankfully, the Clear interconnect is flexible -- very easy to snake over, around, and/or through, as required.

The Clear Speaker cable ($4334/2.5m pair) is thicker, with a diameter of 0.6", yet is also quite compliant. At either end, the positive and negative spade-terminated pigtails are wrapped in red (positive) and black (negative) heat-shrink material. The junction of cable to tail is finished in a handsome black splitter cap made of a high-density polymer embossed with Cardas’s nautilus logo. The Clear Beyond speaker cable, which contains twice as many conductors as the Clear at exactly twice the price ($8668/2.5m pair; add $700/pair for biwire), resembles a hose, being just under 1” in diameter. As my review sample was configured for biwire operation (Clear Speaker cables can’t be biwired; for that, Clear Beyond is required), the amp end had a single set of spade connectors, while the speaker end sported two sets, labeled High and Low. Again, and especially considering its not-insubstantial diameter and heft (its 5AWG represents a significant amount of copper), the Clear Beyond was surprisingly supple.

Geometry, materials, connectors

Wire is wire, some say, and requires only an appropriate combination of resistance, capacitance, and inductance. Not according to George Cardas, who adds to those factors “conductance, velocity of propagation, radio-frequency radiation and absorption, mechanical resonance, strand interaction, hysteresis, high filtering, wavy serial impedance and reflections, electrical resonance, dissipation factors, envelope delay, phase distortion, harmonic distortion, piezoelectric effects, hall effect, field effect, voltage and current tracking, thermoelectric phenomenon effects, structural return loss, skin effect, corrosion, cross-talk, bridge-tap,” and more. It’s enough to make one’s head spin.

While there may not have been a text for audio cables at the start of the 1980s, Cardas Audio has, in the ensuing 30 years, developed strategies to address the complex matrix of variables informing audio cable design. The terms Golden Section Stranding, Matched Propagation, Constant Q, Crossfield Construction, Pure Copper, and Litz constitute a distillation of the Cardas playbook, providing a balance of materials, manufacturing processes, and geometry to create a whole that exceeds the sum of its parts. According to George Cardas, the Clears represent the realization of the ideal he has chased for the past three decades, with the Clear speaker cables adding these wrinkles: Perfect Mirror Quadaxial (Clear Speaker) and Perfect Mirror Octoaxial (Clear Beyond). While many manufacturers hide their designs behind a wall of secrecy, claiming “proprietary” material science and geometries, George Cardas & Co. were happy to discuss what all these terms mean, and how they implement them in the Clears. Let’s examine each more closely.

For George Cardas, cable design begins with geometry, a fundamental embodied in the Cardas logo itself: the cross section of a chambered nautilus shell. The progression of the increases of these seashells, like so many natural progressions found in nature, conforms to the Golden Ratio (φ), often expressed as a fraction of approximately 1.61803398871. The ancients used this ratio to construct buildings (the Parthenon in Athens, for example), such that the length is 1.618 times the width, which is itself 1.618 times the height. Not only were the resulting dimensions found to be aesthetically pleasing, they were correctly identified as being antiresonant. How else could a +2000-year-old structure survive all the seismic activity of Greece? Recognizing the vibrational energies to which cables are subjected, from both their environment and the cyclic effect of alternating current coursing through their copper veins, and the resultant ringing that threatens to distort the transmitted musical signals, Cardas turned to the Golden Ratio to create electromagnetically stable, antiresonant conductors. The separate copper strands that, bundled together, form a Cardas conductor progress from thinnest to thickest according to the Golden Ratio -- hence “Golden Section Stranding.” George Cardas was issued U.S. Patent Number 4,628,151 for creating Golden Section Stranding audio cable. Constant Q relates to the arrangement of strands within Golden Section Stranding conductor bundles: the thinnest is at the center, with each layer of progressively thicker strands added outwardly toward the cable circumference. This layering allows the thicker strands to mechanically stabilize the smaller, inner strands against resonant vibration, and keeps the relative Q (electrical stiffness) constant.

These basic geometries settled, Cardas focused on matching the velocity of propagation (VPROP) of the solid conductor strands (effectively, the speed of light) to the VPROP of the solid dielectric materials (about 78% of the speed of light). Cardas believes that such a mismatch in VPROP creates a condition analogous to turbulence in a boat’s wake, and in audio cables results in a smearing of the signal and a loss of fine detail. Since it’s impossible to sufficiently increase the VPROP of the dielectric, Cardas again turned to geometry -- this time, vector geometry -- to reduce the relative conductor VPROP to 78% of light speed. In its Matched Propagation Conductors, the fine, individually insulated stands forming the conductor bundles are layered at an angle so that, in a 1m-long cable, each strand is 1.27m long. While the VPROP through each strand remains the speed of light, its relative VPROP over the length of the conductor itself is 78% the speed of light, to match the dielectric material’s VPROP.

In earlier Cardas designs, all but the smallest, center strand of each conductor bundle was made using this vector geometry; now, in the Clears, the geometric ideal has been achieved. In the Clear interconnects, the smallest copper strand is wrapped around an extremely thin, extremely strong Kevlar fiber. In the Clear Speaker cables, the two smallest strands coil about themselves while exploiting the mathematically proper vector. While these solutions sound simple, it took Cardas the better part of 30 years to solve the technical challenges necessary to actually construct his ideal. Further, each layer of spiraling strand reverses direction: layer one spirals right, layer two spirals left, etc. Cardas calls this Crossfield Construction. Such orientation further mechanically stabilizes the conductor matrix and, according to Cardas, effectively reduces radiation and reabsorption of radio-frequency interference (RFI) and electromagnetic interference (EMI). In addition to the geometry-based resistance to interference, and as interconnects are especially sensitive to the surrounding environment, Clear interconnects, like all Cardas interconnects, are also shielded in a series of distinct layers.

The last piece of the geometry puzzle is realized uniquely and exclusively in the Clear Speaker and Clear Beyond by way of Perfect Mirror Quadaxial and Perfect Mirror Octoaxial construction, respectively. Each bundle of strands actually contains two conductors, one formed by the interior nine layers, and the other by the outer two layers (separated by a dielectric insulator). Because of the increasing number and gauge of the exterior strands, the effective gauges of the internal and external conductor layers remain identical. The Clear Speaker comprises two double-conductor bundles. In the first, the “positive” conductor is in the center, and the “negative” conductor is on the outside. The second bundle mirrors the first, with the “negative” conductor taking inner position and the “positive” conductor the outer. Four conductors in two bundles, arranged in a mirror-image configuration, equal Perfect Mirror Quadaxial. In the Clear Beyond, four of these double-conductor bundles are used. Eight conductors in four bundles, arranged in duplicate, mirror-image configuration, equal Perfect Mirror Octoaxial.

“The speaker cables are essentially shielded by their mirrored construction,” Cardas explained, “resulting in extremely high common-mode rejection and, more importantly, field containment. . . . Electromagnetically, the internal bundles form what are essentially mirrored monopoles (each bundle is both plus and minus), so they null each other’s fields while providing a low impedance path -- the result is an amazing low-level clarity that can be achieved no other way.”

Understanding this conductor arrangement explains why Clear Speaker can’t be biwired, while Clear Beyond can. According to Cardas, the termination of these bundles is tedious and contributes to a large part of their cost. Every one of the strands is individually coated with a tough urethane varnish (known as Litz), which prevents the oxidation of the bare copper wire and minimizes strand-to-strand interactions. This enamel must be carefully chemically and mechanically stripped from the end of each of the dozens of strands, after which the internal filaments of one bundle are combined with the external strands from its mirror-image partner. Finally, the spade connectors are forged onto the resultant bundles, and any exposed strands are recoated. Since Clear Beyond contains twice the number of conductors (5 gauge vs. 8 gauge, with half the resistance) and requires twice the labor of termination, it is exactly twice the price of Clear Speaker.

Cardas Audio has always striven to achieve extreme purity in its wire. In fact, because George Cardas believed that the only way to ensure his access to high-purity wire was to control all steps of the production process, his company acquired, early in its corporate history, its own wire-drawing facility. Starting with pure, soft copper, Cardas slowly draws down the billet to the proper gauges in small increments, keeping the wire in an oxygen-free environment (to prevent oxidation) throughout an extended annealing period.

In metallurgy and materials science, annealing is the treatment of a material with heat to change such properties as its strength and hardness. The metal is heated to above its temperature of crystallization, kept there a while, then cooled. Annealing is used to induce ductility (i.e., its ability to be drawn out into wire or thread), soften material, and relieve internal stresses, thus making the metal more homogeneous and increasing its conductivity. For copper, silver, and other metals, this process is performed by substantially heating the material (generally until glowing) for a period and then allowing it to cool slowly -- in the case of Cardas copper, very slowly.

For the Clear line, the process of annealing and drawing has been pushed to a higher level, the result being an extremely soft wire with a very homogeneous grain structure, and a surface that’s almost mirror smooth. The full benefit of such a perfect surface became evident to George Cardas only when he was working with a physicist who preferred this metal structure for his particle accelerator’s sensitive particle detectors. While regular copper was satisfactory for the magnetic coils needed to accelerate atoms, the super-slow-drawn, perfect-surface copper produced consistently superior results in the accelerator’s liquid-nitrogen-cooled detectors.

Now that Cardas had optimized his geometries and his metallurgies had advanced to an extreme degree, he felt the need to reexamine his connectors and the methods used in fusing together conductors and terminations. Unleashing his resourcefulness on the battle-tested XLR connector, Cardas designed (and Cardas Audio makes) an all-new XLR device in which every element has been refined. Milled from billets of nonmagnetic brass that’s also eutectic (i.e., it has the lowest possible melting point), these mechanisms feature rhodium contact surfaces and a unique end-shielding technique that blocks RFI.

Not satisfied with mere refinement, Cardas is unequivocal about his company’s achievements in speaker cables: “The new spade connectors and the connection techniques are, without a doubt, the best ever devised.” To truly fuse the ultrapure copper of Clear conductors to the spade lugs of billet copper, Cardas uses a two-stage, compression die-forging technique in which, using cold-forge dies, 10,000 pounds of pressure are applied in each of two stages to create complete continuity between conductors and connectors. The seamless, homogeneous result provides an unhindered flow of electrons from conductor to connector, as if there were no joint whatsoever.

With all of the innovations incorporated into the Clear line, it’s no wonder it took Cardas 30 years to achieve. The million-dollar question remains: Are the Clears worth all that time, effort, and expense?

System

The Clear cables were installed in my main system for many months. A 1m run of single-ended Clear interconnect connected my VPI Scout turntable to my Aesthetix Rhea Signature phono stage. Through the rest of my system, Clear balanced interconnects (utilizing Cardas’ newly designed Clear XLR connectors) held court, connecting the Rhea and my Ayre Acoustics D-1xe disc spinner to my Ayre KX-R line stage, both of which sit on a Harmonic Resolution Systems MXR rack with M3X shelves along a sidewall of my listening room. The KX-R was, in turn, tethered via a 6m run of Clear XLRs to my Ayre MX-R monoblock amplifiers, themselves coupled to custom HRS M3 platforms. Given the biwiring requirement of my reference Vandersteen 5A loudspeakers (and Vandersteen’s Model Sevens, which I reviewed toward the end of my time with the Clears), a 1m, biwired pair of Clear Beyond cables connected speakers to amps. Power was delivered via Cardas Golden Reference AC cords and Ayre L-5xe passive power conditioners.

Listening

While I had enough Clears on hand to wire my entire system, I installed them in a progression based on my prior experiences with wire, where I thought their impact would be greatest. First, I changed out my Ayre Acoustics Signature speaker cable with Clear Beyond. Second, I connected my VPI Scout to the Rhea Signature with a 1m pair of Clear interconnects. Then I linked the phono stage and disc player to the preamp. Finally, I tethered the preamp and monoblocks. To get a sense of the impact each change made, I made these changes, in the stages just listed, over the course of a month. During my time with the Cardas Clears, I swapped out cables to further refine my analysis. In each case, and wherever applied, the Clears distinctly improved the performance of my system over the Ayre interconnects and speaker cables.

Cardas cables have a reputation for needing time to settle (a term that makes more sense to me than break in), following the physical manipulation required to get them in place and connected. George Cardas believes that such manipulation temporarily affects the wires’ ability to distribute a dielectric charge as well as their mechanical stability. Regardless, whenever I swapped out cables for comparison purposes, the Clears’ sound always benefited from a day or two of use -- after which they fully relaxed and opened up.

The Clears had an ability to transmit intact the microphonic cues present in the music, a quality that became most evident when the Vandersteen Sevens were introduced into my system. With their pistonic drivers, incredibly inert cabinets, and time- and phase-correct crossovers, the Sevens can deliver a dynamic and holographic musical experience the like of which I’d never before enjoyed. As good as they are, however, the Vandersteen Sevens can transduce only the signals they are provided, and will expose a recording’s deficiencies as well as its splendors. With the Sevens and the suite of Clears in place, my system was transported to an entirely new level. Examples filled my notebook, two of which follow.

One of the reference discs I’ve recently come to rely on is the 45rpm, 180gm reissue of René Leibowitz and the Royal Philharmonic Orchestra’s The Power of the Orchestra (RCA/Analogue Productions AAPC 2659-45). In Mussorgsky’s Night on Bare Mountain, the RPO delivers fantastic dynamic range, often within near-instantaneous transitions, and there’s even a wind machine at the climax. Often lauded as one of the greatest-sounding recordings ever, it can challenge all components of a system. Through the Cardas Clears, the string section had an analog rightness, with none of the shrillness or congealed uniformity sometimes heard from hi-fi equipment. I focused on the percussion in this tone poem’s later passages, when the repeated striking of a church bell signals the dawning of a new day. To make a bell ring true, the attack, overtones, and decay must be naturally presented -- a feat that requires impeccable timing, tone, and multi-octave balance. Listening to my Cardas-wired system, more than one visitor commented that that bell sounded real.

In a galaxy far, far away, as the rest of my family slept, I found myself watching the DVD edition of Star Wars Episode V: The Empire Strikes Back through my main system (home theater 2.0, rather than 5.1 or 7.1), at very modest volumes. While Yoda was putting Luke through his Jedi training on Dagobah, I was disturbed by a noise almost 90 degrees to my left. Only when I got up and walked to the window did I realize that the noise had come from the soundtrack, and was part of its ambient soundscape. While this verisimilitude was partly due to the dynamic contrast and incredible imaging of the Vandersteen Sevens, I credit the Cardas Clears for transmitting the aural information intact, without loss, time delay, or other distortions, any of which would have robbed this effect of its efficacy.

To ensure that my grasp of the Clear interconnect’s sonic capabilities was as grounded as possible, I performed an extended series of A/B comparisons using 1m balanced runs of Clear, Ayre Acoustics’ Signature ($1000 per 1m pair), and AudioQuest’s Sky ($2600 per 1m pair) and Wild Blue Yonder ($4200 per 1m pair). As my Aesthetix Rhea Signature phono stage has dual XLR outputs (in addition to its two RCA outputs), it was simply a matter of running parallel lengths from the Rhea to adjacent inputs on my preamp. Using a single source and level-matched inputs, I was able to toggle between the Rhea’s two outputs on the fly to identify even the tiniest differences. To focus on what I was hearing, whenever possible, I let visitors control the input control during these comparison sessions. Further, these sessions occurred only after the two chosen cables had been installed and used for several days. Under these conditions, any differences were obvious and repeatable, however subtle. Anyone who claims that cables don’t make a difference, or that they all sound the same, hasn’t critically auditioned them in a familiar system.

Given my years of using Ayre’s Signature interconnect, that seemed the best starting point, especially as I’d flirted with Cardas’s Golden Reference ICs before buying the Ayres. In earlier evaluations, I’d ultimately preferred the more evenhanded balance of the Ayres throughout the audioband. I felt the Golden References had a touch too much midrange bloom, trading a pleasant musicality for the last bit of neutrality, even if they were much more neutral than the label of “euphonic” many had slapped on Cardas wire might have led me to expect. The Clear proved to be a different animal: tonally very similar to the Ayre, but ultimately outdueling it in neutrality. At the same time, the Clear plumbed deeper, resolving information with a finer grain. Most important, with the Clear, the sound simply relaxed, feeling more enveloping and natural. Notwithstanding the high regard I have for Ayre’s Signature, especially at its price, I have to conclude that, between the two, the Clear will provide an improvement in the sound with almost any system.

Comparisons with the AudioQuest cables proved enlightening. The Sky was every bit as resolving as the Clear, but seemed “faster,” tipped up just slightly, with an emphasis on the upper octaves. Lost, however, was a bit of the full-bodied, almost “organic” sensation I found so engrossing with the Clear. Rather than the many-layered, stranded approach favored by Cardas, AudioQuest champions solid-core conductors surrounded primarily by air (channeled through Teflon sheaths of much greater diameter). I wondered if these differences were responsible for what I was hearing. Yet when I changed to Wild Blue Yonder, all of the characteristics I was responding to with the Clear came flooding back. The Wild Blue Yonder takes the same approach as Sky, but with larger-diameter air-tubes, additional layers of shielding, and, perhaps most important, XLR connectors machined from soft, highly refined copper and plated with 100µm of pure silver. Ultimately, the Wild Blue Yonder matched the strengths of the Clear -- neutral, refined, and extremely engrossing -- while providing a smidgen of added resolution, but at twice the price. In most systems, I suspect the choice between the similarly priced Cardas Clear and AudioQuest Sky will probably come down to system matching and listener preferences. In my system, I preferred, however marginally, the results from the twice-as-expensive Wild Blue Yonder.

These comparisons validated my months of prior observations. The Cardas Clear cables did nothing obviously wrong, and so much obviously right. Of all its qualities, the Clear’s greatest attribute was its enveloping, open, unrestricted musical flow. In this regard and in my personal experience, only AudioQuest’s Wild Blue Yonder and Kubala-Sosna’s Elation cables can match it.

Keeping everything in perspective

Cables are just one part of a high-performance-audio system. Depending on the nature of the sources, electronics, speakers, and, perhaps most important, the room, no single cable brand can be expected to be best for all systems. What helps make one system sing can be ruinous in another. I am lucky to have a good-sounding listening room that doesn’t introduce any overwhelming problems of its own. Accordingly, my reference system comprises components that are both neutral and revealing. In that system, the suite of Cardas Clears furthered my quest -- it has been a delightfully musical pleasure to live with these wonderful cables and interconnects for the past months. Based on my experiences at home, I suspect that Cardas Clears will be a great choice for many -- a suspicion supported by the profusion of disparate, good-sounding systems at the 2010 CES that relied on Cardas Clear cables with good results.

By a significant margin, the Clear cables are the most expensive Cardas makes. Nevertheless, they’re almost cheap by reference-cable standards, and represent a true value among state-of-the-art cables, based on both the ratio of component/manufacturing cost to MSRP and, especially, the performance they provide. With the Clears, Cardas Audio has vaulted forward along its 30-year path, achieving new levels of neutrality, extension, resolution, refinement, and (dare I say it) clarity. From my perspective, the Cardas Clear line is an all-around achievement. Congratulations, George!

. . . Peter Roth
peter@soundstagenetwork.com