July 2010

Digital Cable Comparison Review
Teo Liquid Cable, Harmonic Technology Photon and Audio Sensibility S/PDIF Digital IC.
A Tale Of Three Cable Technologies
Review By Rick Becker
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  Many months ago a friend of mine on the Left Coast asked me if I would like to borrow his new Harmonic Technology Photon Digital cable. I scoped out Robert Levi's review on PFO and liked what I read, but choked on the price of this new and improved version of their CyberLight technology. I accepted Arnie's offer but both of us being busy people, the exchange never happened. That is until recently when he repeated his generous offer. After all, it isn't every day that I get to listen to a $1900 cable, digital or otherwise. But don't stampede for the beer cooler just yet if it‘s too rich for your blood. This is a tale of three digital cables.

Since the Montreal show of 2009 I had been talking with Brian Kurtz, the distributor of the new Teo Audio Liquid Cables. First the delay was all about the development of a more cost effective PDL series. Then it became an issue of availability. In this price range they don't have lots of sets lying around to hand out to reviewers. A dealer on the West Coast had loaned the set I was supposed to get to a customer who was taking a very long listen. When I mentioned that I would also be interested in a digital cable, my request was greeted with enthusiasm. Shortly after the Harmonic Tech cable arrived, so did a 1-meter Liquid Cable digital cable and a set of 2-meter interconnects. At $749 for the digital cable and $1249 for a 1m pair of interconnects ($2375 for 2 meter length) these "entry level" cables from their PDL series were also more than I would be comfortable spending, but the curiosity about this new technology was too compelling.

The third cable came about from an encounter at the AuDIYo.com space at this year's show in Montreal. I call it a "space" because not only did they have a room with a rig, but they spilled out onto tables in the hallway. This is a perennial hot spot at the Montreal show that always has a multitude of interesting products. This year I met Steven Huang of Audio Sensibility, a New Kid on the Block in the crowded audio cable field. It took a few minutes for me to recognize that he is a serious player whose personal history goes back to the dinner table when he and his dad used to sit around and talk engineering with Dr. Ohno. Yes, Dr. Atsumi Ohno of single crystal wire fame. But the key word here is "Sensibility", so let's all adjourn to the refrigerator for a cool beverage and start the review.

The Starting Point
Any reviewer will likely tell you they have a pretty damn good sounding rig and I'm no exception. But deep in our hearts we all know (or at least suspect) it could be better if only we had more money. My new preamp made that perfectly obvious. Since almost the beginning of my tenure in this sport I've been running a Sony CDP X77ES CD player as my transport and a Muse model two DAC. Both were Stereophile Class A in their day, but their day goes back to the mid-1990s. I've squeezed a lot of horsepower out of them with the use of ERS paper, AVM (Anti-Vibration Magic), Boston Audio TuneBlocks and Sound Dead Steel IsoPlates. The captive zip-cord power cord of the Sony was replaced with a generic shielded power cord and the Muse uses the very fine JPS Labs Digital AC power cord. The digital cable began with an Illuminations D-60 that was the darling of the Stereophile set at the time, and progressed through two versions of Chris Sommovigo's entry level Stereovox cables, the HDXV and the XV2, each providing a significant improvement over the previous cable at very reasonable prices. But four years have lapsed since I have tried another digital cable. I was certainly ripe for this review.

Harmonic Technology Photon Digital Cable
While this may be new territory since Levi's review did not include the digital cable, the outcome is essentially the same. At first listen I had another of those "Oh, My Dog!" experiences and began to pray Arnie would forget he loaned me his cable…for a very long time. In essence, this produced the most neutral, transparent and highly focused music I've heard in my home or pretty much anywhere else except for the occasional ultra-expensive rig at an audio show. With triode pre and power amplification the music was completely non-fatiguing. The downside was it allowed me to clearly perceive the grain from the Muse DAC and the softness in the bass and the lesser loss of resolution in the treble. The latter may be somewhat due to the limitations of the full-range Fostex drivers in the open baffle Tekton Design monitors. The low bass of organ music was better resolved than with my reference cable through the Tekton subwoofers which are capable of true deep bass.

To check off a few more points of interest, the soundstage was slightly more recessed than the Stereovox XV2, but since it was more brightly illuminated and extended further back this was a non issue. The gospel singers in Lyle Lovett's Church were exquisitely perceived at the back of the stage. While the positioning of the instruments and singers was exact in that you could point right to them, it was not so pin point as to be un-natural. They had body and there was a continuity of space. Nobody sang or played in a bubble surrounded by some intra-galactic blackness. Room tone filled that space when it was on the recording and made it more real. It was easy to identify the position of an instrument and follow its journey through the music or to jump from one musician or orchestra section to another as I wished, or as the music led me. With the crisp attack and rapid decay portrayed with this cable (and the supporting amplification and speakers) the dynamics were excellent. I'll come back to the Photon again, but let me proceed to the Liquid Cable at this point.

Teo Liquid Cable
My initial interest in the Teo Audio Liquid Cable came from a comparison of two rooms at the 2009 Montreal show that featured the same loudspeaker model. In the speaker manufacturer's room the speaker was driven by a solid state rig and while it sounded very good, it did not seem to justify the high cost of the speaker. Later on, in a room powered by tube amplification (which I generally prefer) this same speaker sounded considerably more engaging. My propensity was to credit the enhancement to the tube gear, but a conversation with one of the hosts enlightened me about the Teo Liquid Cables in the rig. I was more than curious. In the hall I met Ken Hotte and Taras Kowalczyszyn, the senior partners of Teo Audio, who answered some of my questions and dodged some others, which convinced me that I had to hear them at home.

This year I dropped in on the Teo room and was disappointed in what I heard, probably because the listening situation was not conducive. But it didn't dampen my inquisitiveness for their cables. When they finally arrived — both the digital cable and a pair of interconnects — I was eager to put them in. I started with just the digital cable and was only mildly excited, but I recalled Brian saying they needed time to warm up. So I hung in there. A half hour later, they were singing. Since this is about the normal warm-up time for tube gear, I don't count that as a negative. (My solid-state digital front end draws very little power so I leave it on all the time — not very green, I admit, but overall, I am a low consumer of electricity.)

It didn't take me long to recognize my toe was tapping with enthusiasm. The transparency was certainly equal to the Photon, but there were easily recognizable differences. Most obvious was the longer sustain of the notes. The Photon had a quick decay that contributed to their outstanding focus. The Liquid Cables held on to the notes perceptibly longer. The attack was slightly softer, as was the focus. The positioning of the musicians was not as pin point as the Photon, but the soundstage had a more organic wholeness that made the music seem more real and more natural. Pace, rhythm and timing bopped right along with my toe tapping, perhaps indicating that the longer decay bridged the temporal distance between notes. The soundstage was "full" of music, somewhat masking the exact location of the musicians. But this did not narrow the soundstage as you might suspect, nor did it diminish the transparency. Music that included notes far to the outside of the loudspeakers came across that way.

When I took advantage of the Liquid Cable interconnects to listen to Hearts of Space on NPR on my Sony ES FM tuner I was greeted with the most colorful and enormous musical universe I've ever experienced with that program (and I've heard close to 500 of them). I'm really going to miss this application of the Liquid Cable. But using those interconnects between the DAC and the preamp did not produce the same degree of improvement as using the Liquid Cable closer to the source, whether it was from the CD transport or the tuner. Starting out with the Liquid Cable at the source of the system produced the greatest benefit in my limited experience with the cables at hand.

Left Brain/Right Brain
At this point some readers might be thinking "Well, if one of these cables is right, the other must be wrong." I think not. What we have here are two completely different technologies for transmitting a signal from a transport to a DAC. The Photon does it by converting the electronic analog signal to light and then back to an electrical analog signal at the DAC, thus breaking the electrical ground between them. The Liquid Cable does it by transmitting the electrical signal through a conductive liquid metal mixture of Gallium, Indium and Tin. It should not be surprising that they sound different when carefully compared. But to a casual listener, or even an audiophile just stepping into the room, people will probably admit that they both sound very, very good. But with each cable I found myself listening to the same pieces of music in quite different ways. From my decades of educational video work in psychiatry and psychology I suspected each cable might appeal to listeners who favor either left brain or right brain processing. The brain, after all, is the final component in our systems.

While certain functions are performed in certain parts of the brain, most people tend to favor one side of the brain over the other, though some are equally adept at using both styles of thinking. Basically, the left brain is the more rational and analytical side and the right brain is the more emotional and holistic or synthesizing side. You can search "left brain/right brain" if you want to go into this deeper. The question becomes, do Left Brain and Right Brain people listen to music in different ways? I'm not qualified to answer that question, but I suspect the answer might be "yes". (I'm a right brainer, by the way, and intuition is one of their characteristics, hence I answer my own question from my own bias).

I suspect the more analytical left brain listener will prefer the Photon cable with its precise sound that lets you dissect the soundstage and listen to all the "parts" of the music. The Liquid Cable, on the other hand will get the toe tapping of right brain listeners and bathe them in the emotional message of the music. Is one side the correct approach and the other wrong? I merely suggest you look at the type of listener you might be and see if the cable matches your listening style. I've often wondered if the upgrade merry-go-round is the consequence of people trying to build a system tailored for the wrong side of their brain.

As an aside, it strikes me as somewhat amusing that most concert goers listen to live music with their eyes open, using multiple senses, while many audiophiles prefer to listen to recorded music in the dark, maximizing their auditory sense. Yet many, if not most audiophiles strive to optimize their music systems to sound as much like live unamplified music as possible. Perhaps paying more attention to one's emotional reaction to the music if you're a right brainer or one's ability to dissect the music if you're a left brainer would lead to a more satisfying system.

Audio Sensibility
Audio Sensibility is a direct marketing manufacturer offering three series of cables (Impact, Testament and Statement) as well as a Signature power cord. The Statement Series S/PDIF Digital IC is available with RCA or BNC connectors in a true 75 Ohm cable made with 99.9999% UP-OCC silver in the center conducting wire of this coaxial design. The return is comprised of two separate silver plated copper shields. They prefer you use a 1.5m length, though a 1m length is available at the same price of $199. (Most of us can raise our glasses of beer to that price!) The 1.5 meter length is said to suffer less from signal reflections from the terminations than the shorter length. Additional half meters are $30. The RCA connectors are Furutech FP-126 (gold plated with a PCOCC center pin) but the standard barrel of the plug is replaced with a custom machined and polished 303 stainless steel barrel that provides greater shielding as well as a sure hand grip. This is a non-locking type RCA, but the fit was secure. The BNC connectors are also Furutech, rhodium plated with eutectic cast copper center pin. ERS paper is scientifically and selectively applied beneath the expandable PET outer sleeve to suppress EMI and RFI.

The Statement Series, which features primarily silver cables, is their finest series, though they do not make every type of cable in every series at this time. All of this is in keeping with their stated goal, "to provide the customer with the best value in high end audio cables." Their direct marketing approach obviously eliminates local retailers and the option of "try before you buy". They do, however, offer a 30 day money back guarantee and a 10 year transferable warrantee that should reduce buyers' resistance to a minimum. The samples I had looked exceptionally well made and withstood a lot of switching around without any problems. For more technical descriptions of this or the other cables in this review, please search the manufacturers' websites.

I mentioned Steven Huang's connection with Dr. Ohno so it is not surprising that all but his least expensive power cable use continuous cast metal wire. Cable and connectors are purchased in bulk so the savings can be passed on to the customer. Furutech connectors are cryogenically treated by Furutech and the wire is cryogenically treated at a local facility — all of it, in each series. And finally, finished cables are burned in with an audiodharma Cable Cooker Pro 2.5 before they are sent to the consumer. Our Senior Reviewer Wayne Donnelly reviewed the Cable Cooker and wrote:

What about reviewers? Frankly, I can't imagine attempting to review audio cables without first conditioning them with the Cable Cooker or an equivalent-acting device. Any cable review based only on in-system break-in is in my opinion not worth reading — or writing. (Enjoy the Music.com April, 2004)

So this is not an inconsequential benefit — something you probably will not get from a larger manufacturer. For the record, the other two cables in this review had seen considerable use by the consumer in the case of the Harmonic Technology Photon and as a demonstrator by the distributor in the case of the Teo Audio Liquid Cable. Hopefully, Wayne will approve. From my more limited perspective, most new cables seem to make their most obvious changes within a month or three, but Wayne's review suggests that even greater performance is hidden within cables that transmit very low current. Regardless, I can certainly appreciate the convenience of the Cable Cooker for fast break-in.

How Does It Boogie?
Right out of its modest but sufficient packaging the Audio Sensibility digital cable delivered Major League music quality. At little more than 1/10^th the price of the Harmonic Technology Photon it delivered a very similar sound differing in ways that are hard for me to describe. Coming in from the cold, if I didn't know which of the two cables was in my rig, I'm not sure I would be able to tell you which one was playing with any better accuracy than chance. Direct comparison revealed very slightly less focus and a very slightly longer decay. The other characteristic difference had to do with the space between the notes. The Photon sounded more pure in the sense that the space between the notes had nothing there, unless it was a live recording with sufficient room tone to be heard. Perhaps that has to do with the breaking of the ground connection between the transport and the DAC creating a greater signal to noise ratio. Or maybe it is the difference between the Photon technology and the more conventional wire technology. The similarity was far more striking than the differences, particularly in light of the cost differential. Like the Photon, the Statement had a Left Brain sonic signature which is probably where most audiophiles gravitate in building their system. We're talking excellent soundstage, tonal balance, focus, PRAT, and all-night listenability.

IsoMike & Tin Pan Alley
Using my copy of IsoMike TESTS 2005A in Redbook playback mode illustrated many of my previous findings. Recording live, unamplified music (marching band, orchestra and a flute duet with piano) with the distant microphones in the large IsoMike matrix suspended above the audience results in a very realistic recording that is quite different than multi-mic recordings with the microphones placed in close proximity to the instruments. There is tremendous depth of field and dynamic contrast, but the soundstaging, while highly focused, does not locate the musicians with pinpoint accuracy. What it does do is place you right in the stadium or concert hall and make the leap of faith that you are listening to live musicians incredibly easy. The Audio Sensibility cable allowed my rig to sound reasonably close to an IsoMike demonstration I heard at CES on a rig that cost several hundred thousand dollars. Switching to the Photon cable brought my rig even closer to that CES experience. And finally, after a proper warm-up, the Liquid Cable gave the recordings a more homogenized soundstage, but added more vivid tonal color and decay of the notes that made me feel like the stadium was larger (in the case of the marching band) and made me feel like I was sitting 2/3rds of the way back in the concert hall when listening to the orchestral music.

Switching over to Stevie Ray Vaughan's "Tin Pan Alley", a recording that achieves a very large sense of space and conveys tremendous dynamic contrast with sharp attack against a dead quiet backdrop and subtle nuance of tonal color from close mic'ing, the results upended my expectations. The Photon, with its pure, fast sound, and the Audio Sensibility cables carried the emotional content of the music to a higher level than the Liquid Cable, which lacked the sharp attack on Stevie's guitar and the hits on the drum kit. The slower decay tended to mask the darkness of the background thereby reducing the dynamic contrast somewhat. So, what worked well with many recordings did not work so well with this particular cut. Such is life and this reinforces the typical disclaimer reviewers make about "your music, on your system, in your room."

Fit ‘n Finish ‘n Ergonomics
Three completely different technologies come up with three completely different constructions, as you would expect. The Photon cables require more space behind the component because a tubular strain relief is rigidly joined inline with the RCA connector. The converters are actually so small that they are embedded inside the RCA connector. You will need at least 7.5-inchs clearance behind your transport and DAC, or roughly 3.5-inches more than conventional cables, with no sharp bends at the ends for this 3/8-inch thick cable. Jim Wang, president of Harmonic Technology, tells me the cables are designed to handle normal wear and tear and can be bent, as long as you do not exceed the natural flexibility of the cable housing.

The Photon also looks expensive, if not delving completely into bling with its black fishnet sheathing with a double helix of gold thread winding through it. The under-layer of deep cherry adds to the richness. The ends with black locking RCA connectors and ordinary looking red heat-shrink take the look down a notch. A small wire for the DC connection comes out from beneath the heat shrink on the sending end of the cable. The cable loaned to me came with the INEX Battery Pack IV, which is still available and quite trouble free. (One set of batteries inside charges while the other set powers the converters in the cable, so you are never without DC power.) The new iPure DC power supply uses no batteries. Both DC power supplies lie flat on the shelf behind the transport and plug into your power conditioner. If you're in this league, you undoubtedly have a power conditioner. The Battery Pack IV is well behaved and I left it on for the entire review period since the charger draws little power.

The Teo cable is the most ordinary looking of the lot, only 0.25-inches in diameter with black heat shrink covering the Eichmann copper Bullet Plug RCA jacks and a black jacket. Consequently, it is also the most pliable and easy to work with behind your gear. The Bullet Plugs are a tight fit, which is good because they are a non-locking style, but be careful not to knock your transport or DAC off their vibration absorbing footers when you install the cable.

Curiously, there are little arrowheads on the shrink wrap indicating the direction of installation. I wasn't sure why this is necessary if the conductor is indeed liquid, so I contacted Brian Kurtz. Supposedly, there are small metal conductive plugs at each end of the tube that contains the liquid metal and these pins have a directionality factor. Considering the cost of the cable I decided not to dissect the ends, but I did spend a couple of hours comparing music with the cable running in each direction. At times I thought I heard some differences, sometimes sounding like the phase of the signal had been reversed, but the differences were not consistent, so I kind of passed it off as the power of suggestion. More significant was the experience that this late night session was sounding better than ever, probably because of less activity on the grid. Brian later shared: "In my system, I hear more weight, drive, and jump, both micro- and macro-dynamically on every instrument. Better inner detail, too." Whether true or false, it certainly doesn't cost anything to heed the arrows.

The Audio Sensibility digital cable was the most "normal" looking cable of the bunch. Substantive, at 3/8-inch diameter; svelte, with its custom machined and polished stainless steel sheath on the Furutech RCA plug with heavily gold plated pin and collar; and discrete with only a 1.5-inch black label with gold lettering and a directional arrow. It reminded me of Porsche Design in its early days when it was a more understated design house. I mentioned the engineering rationale of the 1.5 meter length, but the added benefit is that it was easy to work with behind the gear, being reasonably flexible. While the RCA end was not a locking type it was firm, but not as tough a shove as the Eichmann RCA on the Liquid Cable. The Muse DAC required a BNC input, so I used an adaptor with the Photon and Teo cables. For those who have never used them, the BNC is generally a much easier connector to use, but a DAC cable is not likely to require a lot of reconnecting for most folks, so this is of little consequence.

Tone
We've often read that musicians listen for different qualities in recorded music than most audiophiles and are often quite content with gear that most of us would scoff at. One of those things is tone — the quality that makes one violin worth millions while another is worth only a few thousands. Tone is probably also the reason musicians like Jackson Browne travel with an entourage of guitars, while BB King travels with Lucille. One uses tone as a creative variable while another treasures the consistency of tone in a particular instrument. Tone is also captured and altered in the recording process and once again in the duplication phase of mass produced recordings. Achieving an outstanding master tape is no guarantee of an outstanding LP or CD. Musicians tend to listen to the music, not the gear. Audiophiles seem to listen to the quality of the reproduction of the music... and sometimes enjoy the music, too. (I thought you might enjoy some blatant generalizations at which to throw stones.)

Of the three cables, the Teo Liquid Cable was the Tonemeister with richer tonal coloration. The music simply had greater tonal saturation, much in the way Kodachrome was more saturated than Ektachrome back in the Film Age. Similarly, I remember experiencing the Synergistic Research Acoustic ART system at CES and picking up on how it enriched the tone of the music in an A/B comparison in a room with a very fine rig. For those who might be familiar with these tiny blocks of wood and miniature prayer bowls, the Liquid Cable had a similar, but even greater effect on the music, at a cost that is significantly lower. (Wayne Donnelly has told me of an even more cost effective version of the ART system at a much lower price that achieves perhaps 75% of the expensive ART system.)

Opto Electrical Isolation?
In talking with my brother, who is a manufacturer's rep for a high tech company, I mentioned the unusual design of the Photon cables and he quickly came back with "Oh! That sounds like opto electrical isolation." I took a brief foray into cyberspace and learned that this concept is used all over the place and can come in the form of a small chip that costs less than a dollar. It can also be a lot more expensive. The challenge for Mr. Wang was to take this concept to the highest degree for high end audio, and to make it small enough to fit into an RCA and XLR plug. It is easy to build this concept in a big box, but much more difficult to make it small and to raise the quality to perfection. His original box design about eight years ago was 10,000 times as large as the unit inside the RCA connectors and had the audible quality of a telephone signal. Smaller parts and more complicated design translate into higher cost. Out of a hundred parts he buys, for example, maybe only 10 meet the highest performance standard he has set for the Photon series. Plus, the manufacturing, development and design of the Photon technology occurs right here in the United States of America.

A common place to find opto isolators is in the input connectors of MIDI (Musical instrument Digital Interface) equipment. I don't want to sound like an expert in this field, so I'll ask a naïve question: If this concept is so effective in the Harmonic Technology Photon series of cables, why can opto isolators not be adapted to the components themselves, allowing electrical isolation between low signal components throughout the entire system? This may have been discussed in engineering circles, but given the outstanding performance of the Photon Digital Cable, the question raises keen interest. Mr. Wang talked with me about this and said it was an excellent question. It seems he already has answered the question in 2007 with his INEX Photon Pre-Amp ($12,500) that incorporates state of the art fiber optic technologies. But that is a subject for another review.

Summary
Everybody loves a winner, and in this review I found three of them. The Harmonic Technology Photon is a state of the art digital cable for dedicated audiophiles with finely honed listening rooms and systems. On the one hand, use it to connect your expensive transport and DAC. On the other hand, you could buy this cable instead of replacing your aging DAC — it may well improve your system that significantly. While most will be able to appreciate its many virtues at the front end of the system, fewer will be able to afford it. Harmonic Technology also makes more conventional digital cables at more reasonable prices.

For those who cannot justify the purchase of the Photon, the Audio Sensibility Statement digital cable is a terrific bargain that will leave you with enough change to consider buying a new DAC in addition to this cable. It comes close to the Photon in performance with a similar sonic signature at a small fraction of the price thanks to their direct marketing approach. It is constructed with very high quality materials, incorporates some innovative design features and is assembled with fine craftsmanship.

The Teo Audio Liquid Cable is technologically innovative and expensive due to the high cost of the conductive liquid. It delivers the music in a holistic manner that lets the music arouse my emotions. It frees me from analyzing the equipment and puts my attention on the musicians and the music. This is the cable for those who pay more than lip service to the phrase "enjoy the music."

Company Information
Harmonic Technology
13200 Kirkham Way, Suite 103
Poway, CA 92064

Voice: 858-486-8386
Fax: 858-486-6633
E-mail: info@harmonictech.com
Website: www.harmonictech.com

Price: $3000

Teo Audio Distribution
P.O. Box 81904
Austin, TX 78708

Voice: (512) 377-2834
E-mail: sales@teoaudio.com
Website: www.teoaudio.com

Liquid Cable digital cable: $749
Interconnects: 1 meter $1249/pair, 2 meter $2375/pair

Audio Sensibility
E-mail: sales@audiosensibility.com
Website: www.audiosensibility.com

Statement S/PDIF digital cable (RCA or BNC), 1 to 1.5 meter is $199, additional 0.5m is $30