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POSITIVE FEEDBACK ONLINE - ISSUE 15
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An interview with Jim Aud, Founder and CEO of Purist Audio Design - July 27, 2004
by Vade Forrestor

 

One of the most enjoyable things about reviewing cables from Purist Audio Design, other than the opportunity to hear some outstanding cables, was the chance to chat with and learn a lot from one of the pioneers of hifi cable design, Jim Aud. Jim came to south Texas to work on the South Texas Nuclear Project (one of the last US nuclear power plants) and stayed to build cables.

Launching Purist Audio Design in 1986, Jim takes a holistic approach to designing cables, considering all parameters which influence the sound of a cable, not just a few parameters in isolation. Purist employs two full-time engineers, who work with Jim in designing new cables. They use computer modeling to steer them towards a particular design, and have a machine shop and construction facility that lets them build prototypes to finalize a design. Extensive use of beta testing provides the customer feedback so vital to successful cable implementation. Purist has about 50 beta testers around the country, and two or three bands that try Purist cables under stressful real-world conditions. Feedback from beta testers is used to modify designs into a final commercial product line.

Jim stressed that advances in material science had made it possible to improve the design of cables. Purist was a pioneer in the use of cryogenic treatment, which is now commonplace in cable manufacturing; but which Purist began to use in 1995. They now combine cryogenic treatment with immersion in a strong magnetic field to align the crystal structure of their conductors.

Purist uses a combination of copper, silver, and gold as conductors for the audio signal. Since Purist uses RCA plugs of their own design, they can make them from the same metals used in the conductors, to ensure minimum signal loss. Although Purist's RCA plugs look pretty ordinary (no locking collar here), throughout my tests, they always gripped the input jacks firmly and never even thought about coming out prematurely. If all RCA plugs worked this well, we probably wouldn't have ever needed the locking collar design.

Purist's most advanced technology uses a light source to illuminate the cable's dielectric, which produces an ethereal three-dimensional soundfield that sounds like surround sound from two channels. The Radiant Light Source (RLS) cables basically add this optical illumination to the company's award-winning (the absolute sound's 2003 Golden Ear Award Winner for Interconnect and Loudspeaker Cables) Dominus cables. The Purist web site describes the RLS cables thusly: "The Radiant Light Cable System, newly introduced by Purist Audio Design in 1998, is the only system of its kind in the world. It takes the already superb Dominus cable and adds a special form of radiant-optical fiber. These optical fibers are illuminated by a specially designed light source and radiate light around the conductors. The light changes the properties of the insulation surrounding the conductors, thus minimizing distortion in music reception.

The result can best be described as a dramatic lowering of the cable's noise floor. Micro dynamics that previously lay buried in low-level background noise are revealed. The nuance of musical emotion is laid bare as never before. The stunning improvement achieved through the Radiant Light system affords the reality of a musical experience unlike any enjoyed until now.

I asked Jim if the RLS design had any similarity to the battery-biased designs like Audioquest's Big Cat series of cables, but he indicated it was a different concept. He described the concept of dielectric biasing as older technology developed by Western Electric in the 1930s. And in case you were wondering, the RLS technology comes at a price: $7350 for a one-meter pair of RCA-terminated interconnect cables, with an extra $2500 for the RLS power supply.

A basic design goal in Purist cables since their early days has been cables that are extremely quiet. Cables don't generate noise like electronics do; instead, they pick up physical vibrations from the sound and other sources, and EMI and RFI from a variety of sources, including the sun. The noise picked up by cables doesn't sound like hum or hiss, but instead is a masking effect on the output signal. I don't know if it's measurable, but it's one of those distortions that become obvious when they're removed. It's somewhat like washing a window; you sometimes don't know how much clearer your view through a window can be until you wash it. Maybe the first washing removes half the accumulated dirt, which still gives a dramatic improvement. And then when the second washing removes the remainder of the dirt, the clarity of the image is surprising but obvious. That's similar to the effects I heard from Purist's cables; their budget Musaeus cables were clearly quieter than anything I had previously heard, which produced abundant musical detail without resorting to unnatural high-end emphasis. Then, when I heard the much more advanced Venustas cables, the noise was dramatically lower, as though someone removed two more layers of dirt from the window. The effect is not subtle. A welcome side effect is that you don't have to play music as loud to hear details of the performance.

A hifi system can pick up vibration through cables hanging loose or on the floor, through the equipment itself, or (in some cases) through tubes, which are subject to microphonics. As you might expect, rigid cables tend to pass more vibration. Purist has used two types of shielding to prevent noise pickup from physical vibration. The first was a fluid jacket that surrounded a cable and provided a built-in shock absorber. More recently, a compound called Ferox has been used. Jim describes the fluid shield as more euphonic sounding, while the Ferox is more neutral and extended, with a 6 db improvement in quietness.

Electromagnetic interference (EMI) and radio frequency interference (RFI) problems have been around a long time, and are getting steadily worse as wireless networking becomes more prevalent. Other sources of RFI like cell phones and cordless phones make the home environment even more polluted by electromagnetic energy. Even the sun's radiation, and re-radiation from your house, can generate noise that a hifi system can pick up. Purist's solution to the EMI and RFI problem has been electrical shielding. Fortunately, the Ferox compound is also an effective RFI shield, and is connected to the inner shield and RCA plug at the source end of the cable. But even their AC power cords, which don't use Ferox shielding, seem to be amazingly quiet. When I first plugged in the Venustas power cords (in a system that was already using Musaeus power cords), I was stunned at how much quieter they were, and thus how much more detail they passed through. And that's just the power cords! An attractive spinoff of their effective shielding is that Purist cables don't need to be elevated off the floor.

In a follow-up e-mail, Jim Aud expanded on his " personal design goals for the different series of cables. Museaus was designed to give Audiophiles the most bang for the buck, Venustas is designed to give Audiophiles the most sonics and still have WAF "Wife acceptance factor" and try to hold cost in line. Dominus is all about the sound, end of story. RLS is technology advancements due to material science."

Purist cables are not cheap, but they are very laborious to construct. Jim revealed that a pair of his Dominus RCA interconnect cables take 100 hours to build. So even though they sell for $5250 for a one-meter pair, much of that cost goes to pay for the skilled labor needed to construct the cables.

If any one area of the hifi industry is fraught with bogus engineering claims and junk science, it's cables. Several self-proclaimed experts have declared that cable design is just a matter of simple engineering, and that the performance of cables can be predicted from their standard electrical parameters (resistance, capacitance, and inductance). Jim described a demonstration he had conducted in Japan, where he built several cables, keeping the RLC parameters the same, but changing the geometry of the cables. The sound of the different designs was radically different.

I asked Jim about contact cleaners, and he warned that some of the more advanced compounds might be harmful over the long run by attracting dirt or lint. He recommended using good old fashioned alcohol to clean connectors.

Purist has a sizeable network of experienced dealers who use a simple technique to demonstrate Purist cables: they let prospective customers listen to broken-in cables on their systems. Most of them become actual customers. Then, the satisfied customers augment the sales force with word-of-mouth recommendations. If there's no dealer in your area, Purist will sell direct. Unlike many companies that try to isolate themselves from their customers, Purist talks to theirs. Jim indicated that a typical cable sale involves an average of five calls from customers.

I'm an avid browser on eBay and AudioGon, where lots of interesting audio gear is sold. During my conversation with Jim, it dawned on me that I had never seen any Purist Audio Design cables being resold. Considering how many are sold, that's amazing, and probably indicates how satisfied customers are over the long-term.

Jim closed with a heads-up that Purist was planning something really special for its 20th anniversary. That should be worth waiting for! Fortunately, 2006 is not far off.

 

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