AudioQuest Cheetah interconnects & Mont Blanc speaker cables Page 2
• Insulation stores and releases energy, and because of that fact (my emphasis), insulation is a dielectric.
• The way in which a dielectric behaves—which is to say, the way in which it releases stored energy—changes if and when a charge is present.
• Air is the best insulation because it does not absorb and release energy.
• Whenever a cable does not have a charge on it, it re-adapts back to its uncharged state.
Let me begin by saying I've always thought that a dielectric is simply an insulator—a material without free electrons, and thus a material that resists the transmission of electrical currents—and that the specific use of the word dielectric implies the sort of insulator one might find between two conductors, and which can be permeated by an electric field. Thus the insulation on a piece of wire is a dielectric. So is the varnish on the wire in a transformer, the plastic (or paper, or oil) in a capacitor, and the nonconductive gaps inside a semiconductor. None of that is too terribly out there, and AudioQuest's usage seems defensible if stilted. (Air is certainly a dielectric, too.)
Now let me go back to AudioQuest's explanation for why their new cable is battery-powered: "By maintaining a 12-volt dielectric bias, far above the voltage of audio signals, the DBS (Dielectric Bias System) provides considerably better transparency and dynamics than is possible even from a cable in continuous use." In other words, this is a break-in thing—except that AudioQuest says the term "break-in" is a misnomer because it implies a condition that is both mechanical and irreversible. (I intend to persist in calling this "break-in", however, partly for the sake of convenience.)
AudioQuest claims that the DBS can charge the dielectric in any interconnect or speaker cable so equipped. Their website illustrates the system: an insulated anode wire running the length of the cable, at the center of the bundle of various other wires, and a cathode wire running the length of the cable near its periphery, presumably in contact with the shield, although that bit isn't clear. The positive terminal of the battery—a 12V alkaline in the case of the Cheetah interconnect—connects to the former and the negative to the latter. In effect, the cable's insulating material becomes the dielectric in a DC-charged capacitor, although the limited electrode surface area and the physical separation of the conductors mean that the stored charge is not going to be very large. In fact, it would seem downright insignificant.
The DBS battery pack is an attractive metal cylinder that rides, Koala-like, on the main portion of the cable, with a pushbutton and LED for checking battery condition—something extra for those of us who like to fiddle, as well as for those who mistrust their ability to hear the difference effected by a lack of dielectric bias—and a mini plug and jack as an electrical disconnect.
Back to the AudioQuest literature: "It takes a couple of weeks for the DBS system to reach maximum performance. Since DBS battery packs are attached when [this cable] is first terminated, [it] will be approaching or at peak performance by the time it's installed in your system. Since there is no load on the two standard hardware-store batteries, they will last for years." Call me a hopeless cynic, but no matter how many times I read that sentence, I can't help but translate "since there is no load" into "since they're not really doing that much."
I took a look. In the Cheetah interconnect, the DBS was as described: The anode was an insulated wire at the center, and the cathode was an uninsulated wire near the outer sheath, in contact with the metal shield. While I had the thing open I also admired the workmanship evident in the welding of the conductors to the connectors, not to mention the very high quality of the low-mass silver plugs themselves. (AudioQuest provides specially treated silver cleaning cloths with these cables; Hazel, the dead TV maid, would covet them.) I also examined the DBS on one of the company's Mont Blanc speaker cables. In that one, the anode was a stranded wire, also insulated, at the center of the positive bundle. But I could not locate a cathode wire per se. Instead, the negative wire from the battery pack was connected directly to the negative banana plug nearest to it.
Incidentally, according to the information on AudioQuest's packaging, their finest analog interconnect, the Sky, employs a 24V charge on the cable's dielectric. That is not merely far above the voltage of audio signals—it is far, far above the voltage of audio signals. In their literature, however, AudioQuest makes no particular claim that that is better.
In fact, for all the verbiage on tap, AudioQuest also offers no real explanation of why a DC charge of any amount on a cable's dielectric should affect, one way or another, that cable's ability to conduct an AC audio signal. Then again, neither can I.
Before moving on to my listening impressions, and lest you think that the DBS is the only thing these very expensive cables have going for them, I'll briefly describe their other points of distinction:
• PSS and PSC: AudioQuest uses solid-core, à la DNM: single-conductor solid-core for all their top-of-the-line interconnects, and multi-conductor solid-core, for their speaker cables. Their reason for doing so is categorically the same as that for the classic Litz construction—stranded wires in which each strand is coated with a varnish-like dielectric, to keep it insulated from its neighbors—only taken up a notch: preventing strand interaction and the distortions induced thereby. AudioQuest claims they select extremely high-purity metals for their solid-core, which they refer to as perfect-surface silver (PSS) and perfect-surface copper (PSC). These, they say, minimize harshness and other distortions associated with grain boundaries in metals.
• SST: AudioQuest states that "any single size or shape of conductor has a specific distortion profile." Consequently, in designing and manufacturing their newest speaker cables, AudioQuest tries to minimize the audible effects of these distortions by spreading them thin, so to speak, with multiple solid conductors of four distinctly different sizes. The Mont Blanc cables I reviewed contain five separate positive conductors and five negatives, meaning that only two in each group are the same gauge as one another.
• Conductive Insulation: The negative conductors in AudioQuest's new speaker cables are insulated with what the company describes as "partially conductive" carbon-loaded polyethylene. This, they say, "damps RF garbage from being fed back into the amplifier." On the one hand, I wonder why this is done to the negative conductors but not the positive, since the two conductor groups perform more or less the same duties. On the other hand, I don't think it matters much, because this is nonsense.
• Teflon Air-Tubes: Because air is the best dielectric this side of a vacuum (for the reasons quoted earlier in this review), AudioQuest sheathes the conductors in their new interconnects with an especially loose-fitting Teflon insulation—or Teflon Air-Tubes, as they call them. The polyethylene insulation in the company's less expensive interconnects is now called PE Air-Tubes.
• Triple Balanced design: AudioQuest's new top-of-the-line analog interconnects all contain three solid conductors, each in its own Teflon Air-Tube. In cables that are intended for unbalanced use—terminated with RCA plugs—two of these are ganged together for use on the negative run, which AudioQuest says involves "a much higher potential." In cables intended for balanced use—terminated with XLR plugs—each conductor, of course, has its own purpose, distinct from the others.
In both instances, AudioQuest claims that the shield is "never used as an inferior audio conductor"—which strikes me as a bit odd, because, in an unbalanced cable, there shouldn't be any signal electrons traveling through either the negative conductor or the shield in the first place. And if there were, the fact that the Cheetah's ground conductors are, in fact, electrically connected to their shield at one end would force the user to resort to much scolding of electrons in order to coax them along one but not the other. Bad, willful electrons!
• Counter-Spiraling "Earth Feature" Geometry: Also in AudioQuest's new top-of-the-line speaker cables, the conductors in the positive bundle are wound in one direction, and the conductors in the negative group are wound in the other. This keeps the conductors in the two groups from running parallel to one another, thus minimizing electromagnetic interference and the musical distortions it creates.