Dave Duvall

November 1997

Kimber BiFocal-XL Bi-Wire Speaker Cable
Kimber PowerKord AC Power Cord

It ain't just wire, dadblast it!

Man, if I hear that "wire is wire" one more time I'm gonna offer some up for a noose! Any fair amount of time spent with cables and interconnects will at some point clearly demonstrate differences do exist sonically. I firmly believe that just about anything you do to a system will "change" the sound; the trick is knowing if the change is for the better. Once you've got a system of components that suits your fancy, it's time to take it one step further with synergistic cabling. Interconnects work with a low level signal. While selecting good interconnects is very important in a system’s makeup, paying greater attention to speaker cables is the way to go, in my opinion. Speaker cables, which carry much higher levels of current and voltage, react more with connected components. Speaker cables are also the last thing the signal sees before it hits the speakers. This makes the amplifier to speaker connection an important juncture to "throw a few bucks at."

Once you've settled your cable and interconnect issues, push the boundaries of "what if" a little bit more – try taking a listen to high-end power cords. You may just walk away as surprised as I was. Please read on…

A man on a mission

Ray Kimber's background in the installation of professional sound and lighting systems led him to understand how it was that cables act like antennas, collecting noise and sending it through the sound system.

His search began as a way to prevent the speaker from picking up this noise. Stranded cable in a steel conduit worked well to get rid of noise, but the hysterisis distortion was intolerable. That led to experiments with multiple gauges of smaller wire, twisted tightly together, which ended up with cancellation problems that created out of phase, distorted, shrill sound. It was concluded that the noise problem was conquered, but to make a cable that sounded "good," they "needed to twist the cables in opposite directions so they would null each other out like two North Pole magnets."

It was 1977 (damn, that seems like just yesterday) when Ray asked a tow-rope company to try braiding cable for him. It was a disaster. The cable wasn't "limp" and the process stripped the insulation.

Shortly after leaving the company he had been working for, Ray hit the streets to find an investor and seek out the manufacturer of the tow-rope machine. After much experimentation, a machine was developed that generated Kimber's first product - 4PR. Today, 4PR is still their entry level cable and has been a long time resident in my wife's system.

Kimber BiFocal-XL Speaker Cables

The BiFocal-XL loudspeaker cable is designed for full range, bi-wired speakers. A total of 36 hyper-pure copper VariStrand conductors are used in its construction, all of which are insulated with Teflon dielectrics. 12 conductors, with an aggregate gauge size of two times 11.5awg, are used in the "inner" circuit. 24 conductors, with an aggregate gauge size of two times 8.5awg, are used in the "perimeter" circuit. The outside diameter of the cable is 1.25 inches (3.2cm) and is finished in a semi translucent satin black.

The BiFocal series loudspeaker cables are designed for loudspeakers with bi-wire connections. Kimber also makes the BiFocal-L model for small 2-way bi-wired speakers and tube amplifiers which may not benefit from the extra conductor mass found in the XL. Termination of the BiFocal speaker cables is done only by the factory. WBT (CE compliant) banana plugs are recommended. Since they are "stackable," they will also allow the cable to be used for standard, non bi-wired, speakers. As well, Kimber's PostMaster spade lugs may be substituted at no additional cost. The Postmaster spades were requested for my review pair. While they do make a good connection with just finger tightening, the compressible silicon wafer between the contact plates tends to bulge out around the edges and needs to be tucked back in from time to time. Not a big deal, and I suppose if your going to squish something between two pieces of metal (the contact area of the spade), then science says it has to be displaced somewhere.

Sean Casey from Kimber Kable states that the "BiFocal loudspeaker cables allow music to run pristine, essentially untouched by external influences like vibration & EMI or by internal distortions such as resonance and destructive electrical relations. We begin these very complex cables with a special acoustic damping core. Over the core, which becomes adhesive with pressure, is braided the upper frequency conductors using an ideal braided geometry. Positive conductors are interleaved with, and counter rotate the negative. Over the upper frequency conductors we braid a compliant damping material that locks the conductors to the core and provides acoustic isolation, it also assists in the electrical isolation of the circuits. The lower frequency conductors are then braided over this second acoustic damping layer. The proprietary electric/geometric relationships found in the BiFocal cables represent a major musical step forward in loudspeaker cable design."

According to Sean, "While they have the appearance of "internal bi-wiring" they are true bi-wired cables with completely isolated circuits from the amp. They are isolated mechanically and electrically. The electrical isolation has to do with our braided geometric relations and not with metallic screens. It seems that other cable companies are marketing cables that are not true bi-wire cables; that is they are not isolated electrically, allowing the electromagnetic and electrostatic fields of the two circuits to interact."

Kimber PowerKord AC Power Cord

The Kimber PowerKord is all about delivering the raw AC power to your components as cleanly as possible. Make no bones about it, power line conditioning is important. Every bit as important is transferring the "conditioned" AC to your gear as undisturbed as possible.

The design of the PowerKord is said to cancel intra-conductor interactions. The theory is that a magnetic field is created as the electric current flows through the conductor, and that this magnetic field adds noise and distortion as it comes into close proximity with audio components. The PowerKord is said to deliver the power and leave the magnetic field back at the outlet, as well as eliminate induced current flow in the ground lead, thus lowering overall system noise.

The PowerKord features Kimber's counter-rotating geometry braiding, claimed to effectively cancel unwanted magnetic fields. An eight wire braid format per leg, netting two 12 gauge conductors, surround a 14.5 gauge ground wire in the center. The cable itself is covered with a flexible corrugated plastic sheathing. The standard PowerKord uses a 15 amp IEC equipment end plug on one end, and a "spec" grade male plug on the other.

Review System

From top to bottom of the ol' rack as follows: The Audio Alchemy DDS PRO transport feeds the DTI.Pro 32 and a Dusty Vawter modified v3.0 Digital to Analog Converter (both Audio Alchemy products). Digital signals are passed along with Audio Magic Mystic Reference I2S cables. Powering the Pro 32 and v3.0 is the Monolithic MPS Power Supply. The control center of this system is an Audible Illusions L-1 (Seimens 7308 tubed) preamplifier. The McCormack DNA-1, 185 wpc (into nominal eight ohms) stereo amplifier provides the muscle to bring the PSB Stratus Gold speakers to life. Interconnects between the DAC / preamp and preamp / power amp are Cardas Cross. Providing "conditioned" power to the entire system is the TAD systems Power Purifier, which is plugged into a hospital grade outlet (and isolated ground) on a separate 15 amp breaker.

All but the power amp reside on a home brew rack. The McCormack amp is based on a homebrew sandbox isolation platform. All rack components are pneumatically isolated with low inflated inner tubes sandwiched between the shelf and a piece of ¾ inch MDF. A larger inner tube is used between the sandbox tempered glass top and the MDF supporting the power amp. The room is roughly 18 feet x 28 feet with a sloping ceiling, and five home brew absorbers provide tight imaging.

But do they deliver the goods?

The BiFocal-XL speaker cables are a good news, bad news situation for the Workin' Type. The good news is that they do deliver an honest, spatial path to the music. The bad news is the 4.0 meter pair (approx. 13') pair reviewed retails at $2,000. Shorter lengths are available at less cost (a 2.5 meter pair will run $1400), and I recommend using cables as short as possible. If you're not used to seeing this kind of price for speaker cables, rest assured that in today’s high-end audio world it is not out of line. I suggest 15 minutes reading most any audio products catalog will bring you to a reasonable plane of reference.

It's the classic "How ya gonna keep 'em down on the farm, after they've seen Pair – eee?" My time spent with the BiFocal-XL resulted in session after session of thoroughly involving music listening. Try as I might, I never found any aspect of the cables' musical performance to be unfavorable. Timbre of voice and instruments was natural sounding and real as I've ever heard in this system. Bass was well differentiated note to note, and balanced in level with the rest of the frequency spectrum. Bass "bloat" and "overhang" were absent, giving the PSB Stratus Gold speakers an improved sense of control. The mid treble and up was consistently clean, with a completely natural sheen to cymbals. The metal dome tweeter of the PSB speaker never produced a harsh or steely sound when the Kimber products were in use.

To me, depth is one of the most intriguing aspects in recorded music. It adds tremendously to the suspension of disbelief that, in my opinion, is a major goal of high-end audio. Granted that my current system is not the last word in overall depth reproduction (I still hear the performers within the confines of the wall behind the speakers - some systems can loose the front wall completely), I could hear deeper into most recordings than I had previously been able to. The soundstage took on a higher level of realism. Events that were either artificially recessed or recorded further back from the microphone, truly gave that impression upon playback.

The BiFocal-XL didn't stop a good recording from showing its ambient sound of the acoustic space. A true feeling of air enveloped the performers, allowing me to become emotionally attached to the music. Instruments seemed to float in space, anchored by a sharp focus that would leave no question where in the soundstage that event was taking place. Details made themselves evident without any undue effort to hear them.

I fell under the BiFocal-XL's spell immediately when I noticed its enticing transparency. Clean and clear are the two words that sum it up best. With the Kimber speaker cables, I succumbed to the notion that I was hearing what my associated components were truly capable of. Every piece in a system adds its own coloration, some more than others. I felt that if the BiFocal-XL's were adding anything, it was in total harmony with everything else in my setup.

The PowerKords were not quite as easy to audition as the speaker cables. While the results were easy to come to grips with, getting from point A to point B required a heavy dose of patience. My system has six power cords (including two that feed juice to the high and low current sections of the TAD Power Purifier). Couple that with the fact that my rack has about two feet of clearance behind it, and you've got all the makings of a real workout. Anybody who's come home feeling good about the job they've done after a tough day at work knows how I felt after these exercises. The series of events here required auditioning the PowerKords with one component at a time, and progressively adding cords two through six, with A/B/A comparisons at each step. These listening tests were done after 60 hours of burn-in and then repeated three weeks later.

The Kimber PowerKords brought about a change for the better, in increments as I progressed through individual component testing, and as a full set when all were in place. If I was to only purchase one PowerKord, my listening tests determined it would be to replace the stock cord on the McCormack DNA-1 power amplifier. The power cord has to feed very large current pulses to the amp. The amp can draw current only when the instantaneous line voltage is higher than the power supply voltage in the amp, so there is a large part of the AC waveform when no current can be drawn. When the line voltage goes over the power supply voltage, power begins to flow like no tomorrow. Power amps are more sensitive to this current pulse condition than any other component - not intending to downplay the importance with other components. Second place went to the Audible Illusions L-1 preamp, third the Monlolithic MPS power Supply (powering the Audio Alchemy DTI.Pro 32 and Dusty Vawter modified v3.0 DAC), fourth to the Audio Alchemy DDS PRO transport and the least amount of solo influence was with the Power Purifier. I suspect the reason the Power Purifier was less affected was due to the filtering of the power line once it's been through the Bybee box.

As was predicted before starting to put multiple PowerKords into the system, adding a second through sixth cord to the system in progressive testing added smallish, yet audible, amounts of improvement. Steps towards furthered transparency and a tightening of the mid bass were the rewards of this laborious process. Once all six cords were in place, I came to the conclusion that while one or two PowerKords did add welcome improvement, something extra happened when using all six of the Kimber Kords. The improvement seemed larger than the sum of the parts. When all were in place I noticed the quiet spaces between notes more than ever before. After all was said and done, I felt my audiophile dollars were best invested, sonically speaking, with all six PowerKords in the system. On the other hand, the PowerKords also allow the listener on a tight budget to take it a step at a time -- one now, another later, and so on. Nothing like having options in life.

Dave gets completely wired

Wired in the sense of having all six of the PowerKords and the pair of bi-wired BiFocal-XL speaker cables in line, that is. Anybody who's seen me wired on coffee, would be thankful we're talking about cables here.

Listening to "Blues No More" from Terry Evans Puttin' It Down (JVCXR-0014-2), I heard the crisp snap to the snare drum that I know to listen for. When a product under review doesn't deliver this, it signals the product is lacking in transparency. Inserting my stock power cords and Cardas Crosslink speaker cables resulted in less snap and immediacy. You shouldn't expect $7 per foot speaker cable and stock power cords to perform as well as the much more expensive Kimber products, so don't draw any wrong conclusions about the Cardas cable. It's killer $7 per foot stuff, and even better as a $14 per foot double run. It is just not fair to compare the two heads up dollar wise.

On "I'm In the Mood" from The Healer by John Lee Hooker (Mobile Fidelity QDCD 567), Bonnie Raitt joins in to do a slide guitar, bluesy voice collaboration with John Lee. With the Kimber products, I was able to hear the essence of the mood conveyed by this dynamic duo. Bonnie is slightly left of center and Hooker just right, emitting a real sense of being right "there" with them. Their voices took on a substantial degree of reality, that was not only honest timbrally, but fulfillingly wrapped in the reverberation of the studio. The transparent nature of the Kimber BiFocal-XL and PowerKords resolved spatial and low level information superbly. Seldom do I play a cut twice in a row, unless it's after switching a component for A/B/A testing. After I heard this cut sounding like I had never heard before in this system, my finger found the repeat button for a second tour - real nice.

I also enjoyed classical and jazz via the Kimber Kables. Also Sprach Zarathustra (Sony Classical SMK 47626) was magnificently dynamic to a level I hadn't experienced before. As I continued to nervously ponder the emotional attachment vs. the financial consideration involved with the six PowerKords and the pair of BiFocal-XL, I found the cables seriously eroding my willpower. I enjoyed the way the orchestra opened up and exposed not only the excellence of the performance, but also the quality my real-world system can reproduce. "Bluesville" off 88 Basie Street by Count Basie and his Orchestra (JVCXR-0021-2) left me knocked out. I had no idea there was so much soul in this cut waiting to be released. Yeah, it made me swing before the Kimber products, but not in the same "grab ya by the Huevos" fashion I now enjoyed. The timbre of piano, sax and particularly cymbals on this cut was so convincingly portrayed, I gave up trying to find sonic faults and resisted any further critical listening. Long after the initial "WOW" factor had passed, the Kimber Kables had convinced me that I was hearing very exacting, subjectively correct, musical presentations.

True to the music

If I had to sum up my experience with the Kimber products in a few words, that's how I'd say it....true to the music. I'm amazed at how well the Kimber Kables improved the sound coming out of the moderately priced PSB Stratus Gold speakers (which cost only about $400 more than the BiFocal-XL's!). Though their cost makes them not practical in entry level systems; in mid and beyond high-end systems the Kimber PowerKords and BiFocal-XL speaker cables justify themselves quite well. These cables are of reference quality and will be hanging out with me through many a listening session. As a reviewer, I believe they will be excellent tools in discovering how a product performs. Most importantly, they are excellent tools that, given good company in a system, will truly convey what it's all about -- the music. Outstanding!

...Dave Duvall
dave@soundstage.com