Raising cable explanation

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  • Bob
    Senior Member
    • Jul 2000
    • 802

    Raising cable explanation

    I'm putting this into a new thread since the other has become yet another thread about blind testing. I had mentioned in that thread that one of the rocket scientist at TRW had given me an explanation as to why there was a possibility that it could have some benifit. Now he is back from vacation and here is the email he sent me:

    Bob,

    Here is my explanation, for what it is worth.

    First, picture looking directly at the end of a straight single strand of
    wire, carrying a single AC frequency, and having no dielectric covering.
    The current varying in this wire generates an electromagnetic field (EMF)
    that surrounds the wire. If you could see this EMF, it would appear like a
    perfectly concentric circle representing the value of the EMF at each moment
    in time, expanding and contracting as the amplitude of the signal increases
    and decreases. Now imagine that the wire is carrying many AC frequencies
    simultaneously, and there would be many of these concentric circles varying
    at the same time.

    If we add a dielectric to this wire, it might reduce the EMF, but assuming
    its properties are uniform, it would not change the concentric EMF circles.
    Now, imagine placing this wire and dielectric next to a floor. The floor
    influences the EMF depending on its own dielectric properties, and distorts
    the shape of the EMF to something like a flattened ellipse. This in turn
    affects the shape of the AC current propagating through the wire, through
    something called back EMF. It is as if the wire is now resisting the
    current slightly differently than the ideal.

    Imagine a cable with many conductors. As you know, the manufacturers try
    very hard use very low dielectric shielding (Teflon and air), and to get
    extremely consistent wire wrapping geometry in order to preserve the net sum
    of the EMF to be as symmetric as possible.

    The goal of the cable is to transfer all frequencies with no change in
    amplitude and no change in timing. If there is distorted EMF, it starts to
    delay some of the higher frequencies their amplitude very slightly. Whether
    this effect is measurable at audio frequencies and whether it can be heard
    is subject to debate. There are audiophiles in both camps, as you might
    expect. Like many tweaks, if there is a physical explanation to back them
    up, many people use them whether they can hear them or not. I am
    sympathetic to that philosophy.

    So, a cable elevator should be of low dielectric (connectivity), and raise
    the cable at least 10 diameters or so above the floor. Wood, ceramics, clay
    pots, are good examples. A possible by product of elevators is to minimize
    mechanical vibration of the cable that propagates back into the amp or
    source. I am using plastic cups (not the best dielectric, but mostly
    invisible and high WAF), and a marble support at the end next to the amp for
    vibration reduction. Does it work? Who knows, but I no longer worry about
    the possibility that it doesn't.

    Larry
  • Victor
    Senior Member
    • Apr 2002
    • 338

    #2
    All I can say is, - WOW! We are now into a heavy duty discussion of Electromagnetic (EM) phenomena as it pertains to audio.

    So, without any further ado I would like to state for the record that EM effects have nothing to do with signal propagation at audio frequencies, - nothing at all, not even a little bit. I already feel better.

    In general, the subject matter as treated by the Rocket Scientists from TRW deserves attention simply because it is theoretically sound. However, the question I would like to pose is this, - what does it have to do with audio when we deal with signals negotiating speaker cables at frequencies of up to 16-17 kHz?

    While reading the Rocket Scientist’s opinion I had this vision of speaker cables somehow experiencing the mechanical force as a result of a back EMF and consequently almost dancing before me. Surreal indeed.

    So let me understand this, - the EM field ‘circles’ interact with the floor and are then distorted. Consequently this distortion is induced back into the wire and distorts the signal itself, - is that right? As enlightening as this reasoning might be, does anyone here thinks that raising the cable a few inches of the floor will somehow help matters? Does the wooden floor do better in this regard? This is really funny.

    Seriously, it does not come as a surprise that everything in universe is connected. With this in mind, the Rocket Scientists is correct in principle, however, the effect he is describing is so minute that the noise generated by the power supply in you power amplifier completely tramps any EM effect that might possibly be observed. It will be difficult to measure the back EMF due to the floor, and it will be even more difficult to make any sense of any effect that this back EMF may ever have. One would need imagination for that. I tell you; - solar flares will have just as much, if not more, effect as the proximity of the floor!

    Here is the question I would like to pose to the Rocket Scientist, - how does the THD+N change as a result of the EM interference of any floor, no matter how expensive, and the cable?

    ...regards,
    Vic

    Comment

    • Bob
      Senior Member
      • Jul 2000
      • 802

      #3
      Victor,
      If you go back to my earlier posts you will be reminded that neither of us felt that raising the cables make the least bit of difference in sound, at least what we can hear.
      I was simply trying to answer the original post as to why someone would want to try it. I think you can tell from the tone of Larry's last paragraph, after experimenting to see if there was anything to it he only left them up in the air because they already were and it puts the thought out of his mind.
      Many theories don't pan out, even though they may look promising. Even the silliest of them are worth trying when there is some math or physics that give them at least a little creadance. If you could simply figure it all out on paper there would be no need for testing, especially your favorite blind test.
      I know that you are a skilled DIYer, aren't you ever surprised by the end product? Often some of the most profound discoveries happen accidently or don't make sense at first, then working backwards we discover the reason why they work. The accidental discovery by a nurse in England that babies that were put by windows didn't get jaundice comes to mind.
      Waiting for the science to catch up before willing to try something seems as closeminded as refusing to beleive in scientific observation was in the mid centuries.
      Getting back to the cables, raising them off the floor is a waste of time as far as I'm concerned. Although, you may like it from a visual point of veiw, or if your anal like many engineers are simply so you can sleep at night.
      Don't take the anal part as an insult Victor. My friend Larry is the most anal person I have met, and so are all the TRW engineers that live in my neighborhood. Thank God they are. I believe it is what makes them such good engineers. They could never do the quick fly by the seat of your pants work that I do, and I could never do the thourough investigative work they do.

      Comment

      • bigburner
        Super Senior Member
        • May 2005
        • 2649

        #4
        Victor, do you have any comment to make on the "Speaker wire" thread in Club B&W Speakers at http://www.htguide.com/forum/showthread.php4?t=14595 ?

        Comment

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