• 01-04-2004, 09:26 AM
    Geoffcin
    What's going on here Skeptic?
    OK,

    Cables, and cable theory gets a bum rap on this forum, and rightly so in some cases for it's unscientific approach.

    We've just done some "home-brewed" science here, and I'd like to see what you think.

    I use in my setup a moderately priced speaker cable, the Audioquest GR8. It is a 10 AGW thick cable using 8 LGC Copper conductors in a Helical Array. I wanted to see if a change to Nordost Blue Heaven cables would make any change. Nordost uses a proprietary flat array, and have been touted by many people as one of the best in the business. They are also priced accordingly.

    One interesting thing, and one I would like Skeptic's opinion on, is an artifact that we saw when testing;

    To make it easier to switch out the cables I moved my amp out of the rack, and placed it on a milk carton in front of my CRT TV. The cables were about 6" from the front of the TV, and much to my surprise they affected the picture! The GR8's seemed to be acting like an electromagnet, and you could follow the bass line with the distortion on the screen! The Nordost didn't seem to produce this effect nearly to the same degree.

    The specs for capacitance, resistance and inductance for these cables are within a few hundredth of a percentage of each other, but the electromechanical effects seem to be radically different.

    Now my question is; Can this electromagnetic effect affect the sound?
    If it can, then shouldn't we have a more open mind regarding what can, and cant be heard regarding cables, as I know of no specs to determine what is going on here.
  • 01-04-2004, 03:25 PM
    skeptic
    Tough to say from where I sit
    All electrical cables with current running through them have an electromagnetic field around them unless they are very well shielded (metal conduit is excellent.) And the field varies with the current. There is both a magnetic field and an electrical field. CRT (cathode ray tube) TV sets can be affected by external electromagnetic fields. In fact, it is by varying and controlling the field internally we control the electron beam causing it to scan back and forth, up and down between the cathode and the phosphor screen creating an image. External fields can and do modulate them, usually detrementally. And these fields can affect the flow of electrons in other wires. The Hall Effect is just one example. The question is, are these effects audible? The answer is almost undoubtedly no. While they can cause visual distortions, the ability to cause audible distortions is of a much lower order of magnitude. Take the worst case example of an unshielded power cord, say the one to your power amplifier or receiver right next to your phono cable. Put them close together along most of their entire length and you might hear an audible hum from your speakers. But move them just a few inches away or as much as a foot or two and the hum should become inaudible. The fields are not strong to begin with, they drop off with the distance, and the coupling effect is usually not terribly strong either. In the case of interconnects, the current is infinitesmal so the fields are very weak. The speaker wire carries much more current and is unshielded. Even here though, an effect is not likely. Here's an idea. Twist the left and right speaker wires together. Remove the right signal input cable from the amplifier and replace it with a shorting plug. Disconnect the left speaker cable from the speaker. Reconnect the left speaker cable to an 8 ohm 50 watt resistor, adjust the balance control to the extreme left and see if you can hear any sound from the right speaker with the volume turned up. If you can't there is no interaction worth noting.
  • 01-05-2004, 03:33 PM
    Geoffcin
    Thanks Skeptic,

    I was hoping that this strange effect wouldn't produce anything audible. I certainly didn't hear anything strange to report. The harness behind my audio/HT setup is a maze of wires, and I've never heard any hum or crosstalk distortion either. Other than this curious effect the Nordost/Audioquest shootout went smoothly.

    If anyone is wondering I'm keeping my old interconnects, but I reserve the right to test them against others in the future.