musicandaudioguide
  • Cable Curiosities

    Talking about audio cables is sure fire way to start a comment war. Just this past week, I spent several hours with the top executive of a major audio company in the studio for a chat and some demonstrations.
    He's headed a number of major audio enterprises including one of the premium cable companies. I'm not sure how we got on the topic of expensive power cords but we did. The discussion centered on the fact the designer of the company's expensive cables was not an electrical engineer but had come up with a theory of why power needs solid metal conductors. He assured me that using one of the company's expensive power cords to get from the wall to the component would enhance the low frequency fidelity of any component. I remained politely skeptical...as I have regarding most premium cables...but was intrigued.

    So when an article came across my computer screen titled, "Managing Conductors" from the German publication Stereoplay that seems to have done extensive testing of a variety of interconnects, I was all in. You can read the pdf file yourself by clicking here. It's an interesting article. There are discussions of resistance, capacitance and inductance (the R, C and L that describes the properties of cables) as they apply to electrical cables. And they include a fourth parameter called conductance (the letter G), "which is the reciprocal value of the insulation resistance separating the forward and return conductors electrically from each other".

    The article includes a comparison of about ten different RCA to RCA interconnects...with measurements and descriptions of the sound they produce. Starting with the "Standard red and white 'in-the-box' Cable", the authors continue evaluating cables from familiar high-end cable companies including Mogami, Kimber, Audioquest, Cardas, Clearaudio, Silent Wire, and In Akustik. Prices range from less than one dollar to over $500 for a short 1-meter cable.

    I found it fun that the article includes a couple of very quotable statements. Here are a couple of my favorites:

    "Even if the audio cable manufacturers like to describe cable differences in orders of magnitude, they’re not as critical as speakers or even acoustic modifications of the listening room." In other words, cables might result in very subtle differences in fidelity, but the changes are small, if present at all."

    "...even though there may be a direct relationship between the material cost of audio cables and their selling price, that does not necessarily mean that the more expensive cables provide higher fidelity." It is possible that higher costing cables will change the fidelity of a reproduced selection of music, it is not assured. And it is also possible that more expensive cables will be sound worse.

    You can read through the typical audiophile-friendly descriptions yourself. But there's lots of "sounded decently balanced, however the midrange and presence region appeared milky, opaque and congested", "It sounded impressive, precise, with sharp outlines and stable focus. Details were produced very clearly, without grit. Very spectacular, very informative - A real wow factor with quite vivid presence" and "a beautifully layered spatial impression, open and clear sound, particularly in the midrange".

    But the most fascinating thing about the tests was the ability of readers to download "Hi-Res" downloads of the source track as played from a Pro Tools rig using a Wandler AMI Musik DDH-1 DAC...and the curious results that I got when I did a spectrogram analysis of the various cables.

    Take a look at the spectrograph of the selection as played using the standard Red/White cable and the Kimber Kable Timbre (at $440).



    Figure 1 - The spectra comparing a "hi-res" track using a standard $1 cable vs. the $440 Kimber Kable Timbre. [Click to enlarge]

    I was shocked to see that the Kimber cable has a spectrum with lots of added ultrasonics...frequencies that aren't in the original signal. I checked all of the other cables and none of them strayed from the standard cable in the slightest. The frequencies plots were identical. I even reversed the polarity between a couple of them and the standard original...they zeroed each other out 100%. There was no measurable difference between the items I checked...yet the magazine reviewers found some to have better low end, less "congested sound", etc.

    The real question is what would cause the Kimber cable to produce levels of ultrasonic frequencies that are 20-30 dB higher than the actual signal? And would it make any difference in the fidelity? Unless something in the test files or procedures was amiss, I can't figure it out. I guess I should ask my friend Ray Kimber.

    I'll close by pointing out the obvious fact that the "High-Res" selection...the one at 96 kHz/24-bits...is not actually a high-resolution file. The truth can be found by looking at the flat line on the left hand spectra...there are no frequencies above 22 kHz. In the right hand plot the rapid falloff at 22 kHz is also a guarantee that this is an upconverted CD track. No surprise, but why didn't the magazine and reviewers point this out? Because they don't know any better.