The Smith Chart and why power cords matter

Discussion in 'Modifications and Tweaks' started by Puma Cat, Feb 1, 2024.

  1. Puma Cat

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    Just came across this video on YT today on the Smith Chart.



    When viewing this video, it immediately became clear why aftermarket power cords can provide such an improvement to our audio systems.

    Here's an example what happens when the impedance of the "transmission line" does not match the "load impedance". This mis-match causes a "reflected wave" on the circuit, which you don't want to have, as described in the video. Note how the red dot is "off-axis" to the center-line of the polar plot.

    [​IMG]

    Now, when you have the PC's impedance matching that of the "load", you get a much more ideal response, as shown by the red dot in the plot, meaning, no "reflected wave" in the plot below, which is exactly what you want. And...this is one reason why well-designed aftermarket PCs can provide such an audible improvement in our audio systems: because they can "match" the impedance of the "transmission line" with the "load".

    In our case, transmission line is the PC from the wall AC receptacle, and the "load" is the FWBR* power supplies inside our amplification components.

    [​IMG]

    Don'tcha just love...SCIENCE? :D

    *–FWBR: Full-wave bridge rectifier
     
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    Last edited: Feb 1, 2024
  2. Beefy

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    Which aftermarket power cables measure their characteristic impedance? And how do the reflected waves make it through the transformer to even reach the rectifier?
     
  3. Puma Cat

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    As to which PC companies measure their impedance, my hypothesis is all that of them do.

    This article from Caelin Gabriel of Shunyata Research should answer your second question.
    https://www.gcaudio.com/tips-tricks/why-power-cables-make-a-difference/

    In my direct experience, next to digtal cables (e.g. Ethernet, USB, etc), power cables have the most significant impact on audio quality of a stereo system. These two videos I made coupla years ago demonstrate that with some actual data.
    Link here (sorry, I can't get the video to load directly here): https://youtu.be/g2SAj7aKXGo

     
    Last edited: Feb 1, 2024
  4. Beefy

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    Look forward to those results coming through. I'm in skeptic mode today.
     
  5. Puma Cat

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    Yout'll have to research that info for yourself...I don't have it at hand. Cheers.
     
  6. Kernel Kurtz

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    Because they have a more optimal impedance match? Maybe, but that would be different for every system, no?
     
  7. Puma Cat

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    Read the article I linked to above on why power cords matter. Also, watch the videos i made that I linked to.

    A key reason is their ability to provide DTCD: Dynamic Current Transient Delivery, as well as reduce noise significantly from the AC mains; this is documented with data in the videos i made that I linked to above, above. You can see the actual data on the powerline noise analyzer.

    This video may also be informative:
     
  8. abalone

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    This may be a naive question, but the scale he speaks of in the video is quite different, isn't it? I would imagine that for such long wavelength signals, the effect would be negligible? What explains that there is an effect despite orders of magnitude of difference?
     
  9. Pancakes

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    Let's start with the most obvious question:

    What's the impedence of the transmission line from the power company to your outlet?
     
  10. Kernel Kurtz

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    No idea, but at 60Hz the wavelength is about 3100 miles.
     
  11. ChaChaRealSmooth

    ChaChaRealSmooth SBAF's Mr. Bean

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    Having tried power cables myself at one point, here is my honest, unfiltered opinion on these giant, stiff audiophile power cables:

     
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  12. Armaegis

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  13. ergopower

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    In a vacuum. Say a bit shy of 2200 miles in cable (70% c), But you are definitely on the right track with this response.
     
  14. Puma Cat

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    Not sure what that's got to do with the subject at-hand – ? And, if it did have anything to do with it, what of any practical signifiance could be done about it?

    BTW, while AC from the "mains" is a contributor of noise (you'll know that if you watched the videos I linked to above), the biggiest contributor is from FWBR power supplies of the components themselves.
     
  15. Beefy

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    I'm really confused about what you think is happening.

    The bridge rectifier is isolated from the mains through the transformer. The *transformer* is the load, and the mains do not directly see the rectifier.

    And yeah, the rectifier can create switching noise as they turn off, but I'm confused how you think a power cable fixes this. AND what it all has to do with cable impedance.
     
  16. Puma Cat

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    Not sure what you mean by stiff...here's my Shunayta Alpha V2 NR power cable...
    https://youtube.com/shorts/paIxaPqWNWE
     
  17. Puma Cat

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    Did you read the article cited above, and have you actually listened to the impact of one in a system?
     
  18. Pancakes

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    If you're trying to optimize system impedance (in this case the power grid) you should at least know the impedance the system wants to see. This starts at the power station and is affected by all the power lines. It's also affected by all the loads (thousands of homes with endless things being plugged in). When you know all this, you can take the difference between the DCR of two cables and see how much effect it has. If a 3ft audiophile cable is affecting the power grid we're in a world of trouble.
     
  19. Puma Cat

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    I never said it was affecting the power grid.

    A power cable does, though, have a considerable impact on the quality of an audio system.

    Did you read the article by Caelin Gabriel referenced above?
     
  20. Beefy

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    That article is a whole heap of pseudoscientific gobbledegook, without a shred of evidence supporting it. Although even if we give it the benefit of the doubt and assume that every word is true, none of it supports impedance matching being a factor in the supposed audible qualities of power cables.

    So I'm asking *you* exactly how you think impedance matching plays out here. Particularly in relation to rectifier noise.
     
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