ULTRA AUDIO -- Archived Article

March 1, 2007

GutWire Audio Cables SP-8 and SP-11 Power Cords

As uncool as it might be, I have a fascination with power cords. It began when I started reading about whether or not, after the AC power had already been transmitted through miles of non-audiophile-approved cable from the generating station, that last 6’ of power cord could really make a difference.

My own first attempt to answer that question was to put a cheap plug and an IEC connector on the ends of a few feet of Romex and let it feed my CD player. The treble rolled off, the lowest bass disappeared -- but the sound that remained was distinctly more clean and clear than with a stock power cord. I realized that the answer to the question was pretty simple, after all: Of course power cords make a difference. You might as well debate whether 4" of adjustable nozzle at the end of your garden hose can make a difference in how the water comes out, after it’s gone through 50’ of hose, your home plumbing, and the city’s water-treatment plant.

With that realization, an obsession was born, and I spent a year listening to the sound emitted or amplified by equipment powered by wire that was small gauge, large gauge, multistranded, solid, shielded, unshielded, run through Teflon tubes, configured in different geometries, OFC, OCC, cryogenically treated, non-cryogenic -- not to mention all the different plugs and IEC connectors plated with gold, silver, or rhodium. Finally, I sat back, wounded but sated. I was tired of wire cuts on my fingers, but I’d learned a few things I’d wanted to know. Mainly, I now knew what design elements to look for in audiophile power cords that were most likely to optimize the sound I liked -- or disliked.

So when I got the opportunity to review a pair of new power cords from GutWire Audio Cables, I jumped at the chance to test how useful all my recent experience would be. What I learned is that there’s always more to learn.

Solid core vs. multistranded

The GutWire SP-8 ($1499 USD per 5.5’ length) and SP-11 ($3299 per 5.5’ length) arrived, well packaged in sky-blue boxes, from Richmond Hill, Ontario, a northern suburb of Toronto. Both cords are fat and handsome: the SP-8 has a sky-blue heat-shrink over its IEC connector; the SP-11’s is light brown. The plugs are hospital-grade Hubbell 8215s, and the IEC connectors are audio-grade Wattgate 350s. The cords themselves are encased in sheaths of fairly standard-looking black woven nylon. The effect is businesslike and professional: these are power cords with a job to do.

The SP series of solid-core power cords represents a change in direction for GutWire: the six cords in their earlier series, the Clef2, all use multistranded wire. As of this writing, the GutWire website notes the "improved sound quality" of multistranded over solid conductors, but GutWire partner Herbert Wong decided to use solid-core wire for the SP-8 and SP-11. "We’d always considered solid-core wire to have limited practical application because of its stiffness," Wong told me. "But when we started testing solid-core wire, we liked what we heard."

This is not to say that GutWire has abandoned multistranded cords. "We get great comments from our customers using the Clef2 series, particularly on front-end components," Wong said. "We think the new SP-series cords go best on power amps and make the system sound more powerful." Nor does the change in wire mean that GutWire’s overall goal has changed. Wong: "A cable always has to be musical. That means the cable has to allow you to feel engaged by the music you hear. In practical terms, it means avoiding too ‘clean’ a sound that’s lost its harmonics."

The differences in construction between the SP-8 and SP-11 are significant. Each conductor in the SP-8 comprises three 16-gauge, Teflon-insulated wires (two wires for the ground), for a total resistance for each conductor equivalent to that of a single 11-gauge wire. Each conductor in the SP-11 comprises four 16-gauge wires (three for the ground), for a total resistance for each conductor equivalent to that of a 10-gauge wire. Each set of wires in both cords is then loosely encased in a PVC tube with plenty of air around the wires. The cords’ shielding strategies are also different. While the shields in both are of braided copper, the SP-8’s shield is wrapped around all three conductors, while the SP-11’s three conductors are each shielded individually.

The SP-11 also uses GutWire Electron Rectification Processing (GERP), though Wong said that this term will likely soon change: "Too many people make fun of it." Nonetheless, this proprietary passive filter is designed to maintain neutral tonality while making the presentation faster, improving transient times, and tightening the bass.

Following the advice on the GutWire website, I used both cables for well over 100 hours before beginning to evaluate them. Associated equipment included a Cary Audio 306/200 CD player, a Bent Audio NOH passive transformer-based line stage, a Bel Canto eVo4 Generation II power amp, Salk Sound Veracity HT3 speakers, AudioQuest Panther interconnects, and Paul Speltz Anti-Cable speaker cables. My reference AC cords were AudioQuest NRG-5 ($650/6’), an unshielded cord that uses multiple strands of separately insulated, high-quality, solid-core copper with RF "stoppers" near each end.

GutWire SP-8

With SP-8 cords connected to my CD player and power amp, the first thing I noticed was a greater sense of solidity to the music. Mars, from Yoel Levi’s recording of Gustav Holst’s The Planets [CD, Telarc 80466], had palpably greater weight, the full force of the Atlanta Symphony Orchestra hitting me with more than its usual slam. Furthermore, the timbres of acoustic instruments seemed more natural than with my reference cords. I found myself wondering why I hadn’t noticed that timbres had been slightly "tipped up" by the cables I’d been living with. The bass was deeper, and had more impact, but I was surprised that the treble was also slightly more extended, with more air. The midrange was particularly effective and persuasive with human voices. The soundstage was wide, if only moderately deep. Overall, the SP-8 made a good first impression.

Listening more closely revealed some issues. Details in the music, although abundant, seemed somewhat less clear, and there was a loss of transparency. Sung words were a bit less easy to understand in complicated passages. The most obvious effect was on simple tones with complex harmonics, such as cymbals. With SP-8s powering both CD player and amp for Eva Cassidy’s performance of "Bridge Over Troubled Water," on her Live at Blues Alley [CD, Blix Street 410046], a touch on a cymbal sounded less crisp than with my reference cords. This loss of clarity occurred to a slightly lesser extent when I used only a single SP-8, either on the CD player or the amp.

After I’d spent several days listening with the SP-8s, hearing their sound became somewhat like looking at 19th-century French Realist paintings: convincing from afar, but less persuasive up close, when the brushstrokes and artistic techniques are revealed. But of course, that’s not how the paintings are meant to be viewed. The SP-8s presented the music’s big picture quite effectively.

GutWire SP-11

Befitting a more expensive, similarly designed item in the same product line, the SP-11 made the SP-8’s positive aspects even stronger. The bass remained deep and detailed, while timbres took another step toward sounding natural. The midrange also improved another step, vocals coming through more cleanly, and with greater texture and presence. The soundstage was deeper. A bit of the SP-8’s high-end air seemed to have disappeared, however -- not enough to be bothersome when I wasn’t directly comparing the two models, but the difference was clear.

The SP-11 exceeded the SP-8 in overall revelation of detail. There are two ways to increase detail in an audio system: reduce the background noise, or improve the system’s ability to respond to low-level signals. The SP-11 excelled at the latter, perhaps because of its 10-gauge conductors (my reference AudioQuest NRG-5 cords are 14-gauge). There just seemed to be a lot more going on in the music with the SP-11. In particular, it was rewarding to listen to different orchestral parts and follow individual background instruments in classical recordings, such as of Maxim Vengerov’s performance (with Claudio Abbado and the Berlin Philharmonic) of Tchaikovsky’s Violin Concerto [CD, Teldec 90881].

Most important, the clarity of that detail and overall transparency improved compared with the SP-8. Could it have been more wires per conductor (four in the SP-11 vs. three in the SP-8)? Was it the SP-11’s individually shielded conductors? Was it GERP? Musical details were still not quite as clean and transparency was not as great as with my reference AudioQuest cords, though, and those factors kept the GutWire SP-11 from being the grail of my quest for the ideal AC cord.

After more days of listening, the SP-11 became a comfortable complement to the other components in my system. Another visual analogy, this one photographic: While the SP-11’s colors were extraordinarily realistic, and details up to the middle distance were satisfactory, up close the image wasn’t as sharply detailed as I’d have liked. By comparison, my reference AQ cords were sharper at all but the closest distance, though with slightly fewer details, and colors not quite as true to life.


I spoke with Herbert Wong only after I’d already done most of my listening, and so didn’t learn till then that he thinks the SP-8 and SP-11 provide the most benefit when used with the power amplifier, not the source component. In checking out that hypothesis, I confirmed that my Bel Canto amp did indeed sound "more powerful" (Wong’s words); to lesser degrees, the virtues of timbre and presence were also enhanced. But if the GutWire sound suits you, I found that the SP cords also worked well when feeding the source. I regret not having had some of the Clef2 cords to test out Wong’s hypothesis that the performance of the SP cords was optimized with a Clef2 on the front end and an SP on the power amp.

The Wattgate 350 with gold-plated contacts is arguably one of the best audiophile-grade IEC connectors, but I questioned Wong’s choice of Hubbell 8215 hospital-grade plugs with brass contact blades in power cables costing thousands of dollars. I had a similar question about his use of oxygen-free copper (OFC) vs. more exotic metals, such as Ohno continuous cast (OCC) copper or silver. Wong’s response was simple and direct. "We chose Hubbell and OFC because they represent the sound we are looking for. Sometimes people will ask us why we didn’t use silver wire. We prefer the natural and neutral sound of copper over silver. Cost is not an issue in this matter. We just want to make the cables that represent our view of sound."

Another consideration is cost, and there is considerable competition at the SP cords’ price points. For the $1499 price of the SP-8 you can find fine power cords from many manufacturers, often what they consider to be their own state of the art. At slightly more than twice that price for the SP-11, $3299, you’re in the high-level company of the best (or at least the most expensive) power cords on the planet. Whether or not the GutWires suit you will be, as always, a matter of taste, what you find important in your listening, and what you can afford. GutWire doesn’t sell directly to the public, but through dealers who usually offer an in-home audition.

The GutWire Audio Cables SP-8 and SP-11 give music a unique, big, persuasive, and unmistakable presence. If you savor a natural sound, these power cords might be just what you’re listening for.

…Albert Bellg

GutWire Audio Cables SP-8 and SP-11 Power Cords
Prices: SP-8, $1499 USD per 5.5’ length; SP-11, $3299 USD per 5.5’ length.

Warranty: Five years parts and labor.

GutWire Audio Cables
9019 Bayview Ave., Suite 2B-183
Richmond Hill, Ontario L4B 3M6
Phone: (905) 947-8410
Fax: (909) 947-8736

E-mail: gutwire@gutwire.com
Website: www.gutwire.com

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