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Shunyata Research Sigma Signal Cables

Shunyata Research is mainly known for its high-performance power cords and power distribution products, and so, I suspect, its excellent signal cables have been somewhat overshadowed. The new Sigma line may change that. Shunyata has really hit the mark with its latest top-of-the line interconnects and speaker wire.

I will cover some of the technological, design, and construction features later, but let me cut to the chase upfront: Sigma cables deliver high levels of performance across all audiophile and musically meaningful criteria. Put another way, they exhibit low levels of apparent signal adulteration and concomitant high levels of apparent signal integrity. The Sigmas reduced noise so well in my system that I had to reevaluate what was possible in cables priced well below those in the upper end of the market.

While not inexpensive, at $4000 for a 1m pair for interconnect and $7500 for a 2m pair of speaker cables, I believe the Sigmas are fully cable of competing with much more expensive wires. I could not secure significantly more costly models to make direct comparisons. I was, however, able to compare the Sigmas to the similarly priced Kimber Kable Select KS 1136 interconnect ($3335/1m XLR) and Cardas Clear Beyond speaker cable ($8170/2m) and the Sigmas performed much better than both—and did so to an overwhelming extent. (I will flesh this out later.) Keep in mind, there are several other cables available at multiples of the Sigmas’ prices, but even if you are ready to pony up for über wires you might want to give the Sigmas a try. Their performance could pleasantly surprise you and save you a good deal of money at the same time. I don’t mean to imply the Sigmas are flat-out bargains for the average music lover, only that they are well worth your consideration if you are already in the market for cables in their price bracket and considerably higher.

The Sigmas allowed two different systems—a friend’s and mine—to perform as if the electronics had been upgraded rather than the cables. Everything sounded clearer, more coherent, and more dynamically alive. The noise floor dropped dramatically, so fine details and timbral qualities emerged much more readily. Instruments and voices had more body and depth. The overall soundscape expanded in all directions and became more continuously layered from front to back. To use a visual analogy, it was as if a light mist had been removed from a view of a forest glen. One could see into the scene more easily and discern more aspects of the trees (trunk textures, leaf colors, etc.) and the ground. So too, everything in the sonic presentation became more evident. Tonal colors, dynamic shadings, spatial cues, all sounded more real. Mind you, I had been using Shunyata Anaconda cables (reviewed by Robert Harley in Issue 220), the company’s former top offering, for a while and had found them to also outperform other offerings near their price level. Specifically, Anacondas had a “quickness” that made other cables in their price category sound as if they were slightly “sluggish,” while simultaneously allowing the system to have appropriate tonal richness and a healthy dose of bass impact. The Sigmas are in a whole other league than the Anacondas.

With the Sigmas in play, a small bit of jaggedness during hard transients seemed to be removed from my system. Transients no longer sounded lightly splashy and disorganized—unless they were recorded that way, of course. On some recordings, massed violins sounded both clearer and less strident in their upper range when played at forte levels. The Sigmas did not seem to impose any dynamic restriction or frequency extension limitations, at least no more than the rest of my system delivered in the first place. Accordingly, music with notable dynamic snap came through with wonderful clarity and excitement. Fine details emerged in spades. Solo singers’ subtle lip sounds and the quivers of their vibrato were more readily apparent. Small dynamic shadings and timing shifts that help music sound emotionally compelling were also very clearly transmitted. Those details flowed as part of an integrated musical whole, not as an exercise in “forced resolution” that might initially sound dazzling but become fatiguing over the long term. Music sounded more evocative and expressive as a result.

The sound quality of my system improved with either the Sigma interconnect or speaker wire mixed with other cables, but the sum total of the improvements achieved by using all Sigma cables from source to speaker yielded even better results than the sum of their constituent links would suggest. I recommend a complete set of Sigma cables to realize the full extent of their capabilities. Having said this, if I had to choose between only the interconnect or the speaker cable, I would opt for the speaker cable because of its unique HARP feature.


How has Shunyata significantly mitigated some of the apparent fundamental problems with signal transfer through cables—at least at their respective price levels? I would say it starts with Shunyata’s principal and founder Caelin Gabriel. Gabriel is a scientist by education and worked for a military wing of the NSA in digital signal acquisition and encoding in the early part of his career. He cut his teeth by working on equipment that could detect weak and previously unintelligible transmission signals and then resolve them to usable levels. Much of this approach from his earlier work has carried over to his career at Shunyata. Gabriel uses methodical research results to develop effective combinations of materials, construction, and technologies to reduce noise, reflections, and interference that adulterate signal integrity.

 Shunyata uses Ohno Continuous Cast (OCC) OFE101-grade copper—the purest form of certified copper available—in both its conductors and connectors. (OCC, invented by Atsumi Ohno in Japan, is a process of casting copper wire in molds. As the wire cools, a single crystalline structure is formed throughout the length of the wire as opposed to the standard wire-drawing method, which leaves multiple internal crystalline structures in place.) The sonic benefits of OCC are widely known in the specialty audio cable industry—generally, a smoother, purer sound. What is apparently exclusive to Shunyata’s conductors is their formation to function as a virtual hollow tube. Shunyata says this hollow structure (called VTX) greatly reduces eddy currents—and their associated distortions—randomly generated within a typical conductor’s interior as the signal travels down its exterior.

Shunyata treats all Sigma conductors and connectors with something called the Kinetic Phase Inversion Process (KPIP), which essentially does away with the need to determine a cable’s correct signal direction and to undergo sufficient burn-in before its function is optimized and remains stable. After three years of research to identify the key issues associated with directionality and burn-in, Gabriel developed KPIP to address both. Shunyata actually reveals precious little about what KPIP is and how it works, other than to say it does away with the need for cryogenic treatment. I can tell you, though, the KPIP-treated Sigmas stabilized within the first two or three days of use as opposed to the minimum three weeks I am used to with other audio products. KPIP actually does more than address burn-in and directionality issues. I had some treated and some untreated, completely broken-in—but otherwise identical—Shunyata power cords for a while about a year ago. The treated ones helped my system sound more relaxed and free-flowing with no diminution of any other positive quality. KPIP works and is worthwhile.

Sigma carries over Shunyata’s patented ZiTron technology from the Anaconda model. ZiTron addresses what Shunyata characterizes as “dielectric absorption and re-radiation in signal transmission.” A small, passive electric-field circuit cancels out the electromagnetic field that builds up in the dielectric, and it does so—essentially in real time—as the charge difference between the dielectric and the conductor fluctuate with the flowing signal. With less electromagnetic field absorption in the dielectric and release back into the conductors, the resulting signal is less distorted and transient response is reportedly closer to that of the source itself. Shunyata also uses high-energy sonic welding to join the speaker cables’ conductors to its connectors instead of traditional soldering, brazing, or crimping. Sonic welding apparently joins the wire and connector together at the molecular level and is said to be superior to soldering or brazing. Solder introduces yet another metal, usually with a high tin content, and additional surfaces into the mix and causes signal degradation. Crimped junctions are susceptible to mechanical failure when cables have excessive flexing or twisting forces exerted upon them. Sonic welding reportedly enhances transient response in signal transmission and in its equivalent in power applications—Dynamic Transient Current Delivery (DTCD), as Shunyata calls it.

Exclusive to Sigma are two new technologies—TAP (Transverse Axial Polarizer) in the interconnect and HARP (not initials) in the speaker cable. The TAP device, contained in a small cylindrical-looking structure, is not a “cable network” like those found in Transparent and MIT cables. Rather, some of the TAP parts simply have a larger diameter than the interconnect itself and need to be housed in a larger solid structure. TAP reportedly blocks much of the collateral longitudinally oriented electromagnetic waves that surround the cable while allowing the transverse-oriented waves to pass through. The net result is said to amount to the aural equivalent of the effect one has while looking through polarized sunglasses. TAP reduces sonic glare caused by parallel electromagnetic waves interfering with the signal. I did not have a pair of the same cables without TAP to make a side-by-side comparison, but I will say that I found the Sigma ICs seemed to allow the attached system to have a less “splashy” quality on transients and more coherent sonic characteristics—along with the previously noted positive attributes—than with any other IC that I auditioned during the review period.

HARP is also contained in a small, network-like box, but it too is not a network. In fact, HARP does not alter the frequency response or transfer function of the cable in any way. It does not change measurable capacitance, inductance, or resistance. So how does it work? As with KPIP, Shunyata shares very little about the workings of HARP. I can tell you, with great certainty, though, that HARP is highly effective in improving the overall performance of the system. I heard A/B/A demos of a HARP prototype in systems at the Shunyata facility in Poulsbo, Washington, a while back, and was astonished by how much across-the-board improvement HARP made to even a modest system used in one of the demos. It was as if the entire system’s performance were enhanced in every regard—tonal purity, image focus, dynamic precision, soundstage, and resolution of detail and timbre. It is best applied as close to the speaker as possible; thus, the HARP unit is positioned near the speaker terminal end of the speaker cable.


I am usually skeptical about any “cure-all” audio product, but I have never heard another audio technology applicable to any system with freestanding speakers that qualifies as an unambiguous improvement, rather than a subtle amelioration, or a different flavor, of limited efficacy and only in particular systems. Caelin Gabriel explained some of the “current drift” physics theory behind HARP to me, but I would only butcher his words if I attempted to summarize them—and most likely generate deriding letters from physicists in the process. Let me repeat, HARP is remarkably effective in the overall improvement of the system in which it’s implemented. Shunyata is on to something, here.

Both the TAP and HARP structures did not pose any functional problems, such as getting in the way of other cables or getting hung up shelving; nor do they cause excessive stiffness. Both the Sigma interconnect and speaker cable are more flexible and easier to use than their Anaconda predecessors.

More Listening
I was able to bring a complete set of Sigma cables to my friend Lou’s house to find out if they worked as well in his system as they did in mine. The answer was yes—an unambiguous, overwhelming, yes. Within an hour or two of settling time, the Sigmas helped Lou’s system—an already really nice one—sound more lifelike. The replaced Kimber KS1136 ($3335 1m XLR) interconnect and Cardas Clear Beyond ($8170 2m) speaker cable are a good fit for this system, but the Sigmas allowed it to sound much better in every way. All music sounded more alive, more detailed, more dynamically nimble. Imaging was more focused, and the overall soundstage enlarged with a similarly improved depth layering I heard in my system. The same reduction in glare and underlying electronic noise I heard in my system I also heard in Lou’s. The qualitiy of sounding more organized as well as more vivid followed the Sigmas in both systems.

Shunyata Research has outdone itself with these new Sigma signal cables. No aspect of their performance represented a “worthy compromise” or a retrenchment of one set of sonic attributes to advance a set of others. The Sigmas are flat out fabulous across the key areas of dynamic fluidity and stability, soundstaging and imaging, resolution of detail, tonal complexity, and musical completeness. If you are in the market for cables in their price category—or even substantially higher—the Sigmas should be on your audition short list. Enthusiastically recommended.

Specs & Pricing

Interconnect (XLR or RCA): $4000 1.0m; additional length $200/0.25m
Speaker cable (spade or banana): $7500 2.0m; $8100 2.5m; additional length $300/0.25m

26273 Twelve Trees Lane
Poulsbo, WA 98370
(360) 598-9935

Associated Equipment
Analog source: Basis Debut V turntable and Vector 4 tonearm, Benz-Micro LP-S MR cartridge
Digital sources: Hegel Mohican CDP, Ayre C-5xeMP universal disc player, HP Envy 15t running JRiver MC-20, Hegel HD30 DAC
Phonostage: Moon by Simaudio 610LP
Linestages: Ayre K-1xe, Hegel P30
Integrated amplifier: Hegel H360
Power amplifiers: Gamut M250i, Hegel H30
Speakers: YG Acoustics Sonja 2.2, Dynaudio Confidence C1 Signature
Cables: Shunyata ZiTron Anaconda signal cables, Nordost Heimdall 2 USB, AudioQuest Coffee USB and Hawk Eye SPDIF, Shunyata Alpha SPDIF and AES/EBU, Shunyata Sigma NR power cords
Accessories: PrimeAcoustic Z-foam panels and DIY panels, Stillpoints Ultra SS

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