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  1. #1

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    Default Velocity of propagation ????

    Hey Guys'

    Awhile back Ken Swauger built some of us analog cables out of a RG62a/u 93ohm cable with Kens help i tried to find some of this but it is no longer made with solid copper center conductor. In researching this cable some of the cable had "Velocity of propagation" numbers some had a 66% some higher 79% can someone enlighten me as to what exactly this means? Is higher better or lower better,will it have any effect on what I'm planning on using it for? I'm making 7.1 intewrconnects and running some longer runs for video/audio. I'm leaning toward Canare wire of these two designs LV-77s and L5-CFW both with the Canare RCA's.
    In looking at Beldens site and at all the Coax is where i seen the "Velocity of propagation" numbers but also noticed it on some of the Canare.

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    found it ....it's the percentage the electrons travel at the speed of light. wow I really over thought this....
    carry on

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    The velocity is effected by the materials used....I think a lot or exclusively by the dielectric. One of the big ways it starts to matter is in antenna harnesses when combining or splitting to multiple elements. If you've heard of a phasing harness, (or can remember back to the days of stacking multiple off air TV antennas,) that number enters big into the make up in those kind of cases.

    CJ
    As seen on the AVS forum... "Radio Shack zip cord kicks butt."

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    If your analog interconnect is not at least a mile long don't worry about it.

    "Transmission Lines at Audio Frequencies, and a Bit of History"
    by Jim Brown
    Audio Systems Group, Inc.
    http://audiosystemsgroup.com

    http://www.audiosystemsgroup.com/TransLines-LowFreq.pdf

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    Quote Originally Posted by CoolJazz View Post
    The velocity is effected by the materials used....I think a lot or exclusively by the dielectric. CJ
    correcttomoondo^^^^

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    you can also look up transmission line on wikipedia

  7. #7

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    Quote Originally Posted by Speedskater View Post
    If your analog interconnect is not at least a mile long don't worry about it.

    "Transmission Lines at Audio Frequencies, and a Bit of History"
    by Jim Brown
    Audio Systems Group, Inc.
    http://audiosystemsgroup.com

    http://www.audiosystemsgroup.com/TransLines-LowFreq.pdf
    Quoted from the above source: "These effects are too small to notice in a theater where cables are rarely more than 500 ft long, but they can be quite
    significant on a telephone line that is tens of miles long!"

    The above quote is assuming you are using an oscillascope to analyze the transmission line and audio it transmits. Have you considered that a person's ears and consciouness can in fact hear a difference in a shorter cable length? That is, the velocity of propagation matters in shorter cable lengths and that perhaps oscillascopes cannot detect differences in shorter cable lengths as well as one's ears and consciousness can? I'm not trying to start another debate here, but IMO your thoughts on the subject and some of the information (specifically the part I quoted) is not correct. I believe the velocity of propagation matters in ALL cable lengths. I will state it does matter more and the effects are more obvious in longer cable lengths, of course. But, to state "If your analog interconnect is not at least a mile long don't worry about it." is not a correct statement (based upon my experience). I won't (yet) get fully into the fact that the paper you cited is basing it's results on telephone transmission lines for the resulting audio. I'm sure I don't need to point out that this is a monophonic audio source. And that telephone lines have a much smaller frequency response than modern stereophonic audio sources. I do realise Jim Brown does bring up (modern) balanced audio cables towards the end of the paper, but he does not state what materials or configuration this balanced audio cable is made up of. As CoolJaze stated, the materials the cable is made up of make a difference for the resulting audio a person hears. I again bring up the fact that oscillascopes can only detect as precicely and for what they were designed. Perhaps, the oscillascope cannot pick up material and cable configuration differences in the wavelengths it's detecting. Alternatively, perhaps a person's ear and consciousness can? For newer audio enthusiasts here on the forum, some of the information you supplied (and your statement) is misleading is why I bring this up.
    Taken from a recent Audioholics reply regarding "Club Polk" and Polk speakers:

    "I'm yet to hear a Polk speaker that merits more than a sentence and 60 seconds discussion."

    "Green leaves reveal the heart spoken Khatru"- Jon Anderson

    "Have A Little Faith! And Everything You'll Face, Will Jump From Out Right On Into Place! Yeah! Take A Little Time! And Everything You'll Find, Will Move From Gloom Right On Into Shine!"- Arthur Lee

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    "headrott" the audio signal travels down the cable at about 6 inches per nanosecond. If what you write were true, loudspeaker cross-overs (having orders of magnitude greater delays) would totally destroy the sound. The same goes for vinyl LPs.

    I don't think that Oliver Heavyside had an oscilloscope way back in 1893.

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    Quote Originally Posted by Speedskater View Post
    "headrott" the audio signal travels down the cable at about 6 inches per nanosecond. If what you write were true, loudspeaker cross-overs (having orders of magnitude greater delays) would totally destroy the sound. The same goes for vinyl LPs.
    That is very truncated reply. That is, you addressed very little of what I wrote. For the first part of your quote above, are we assuming telephone audio? Are we assuming telegraph lines? Are we assuming a balanced audio cable carrying stereophonic audio? Are we assuming a single ended IC? Again, since you didn't address what I wrote I will bring it up again. What cable configuration, dialectric materials, and metal(s) are we talking about that make up this cable? I believe you completely missed or skipped over the points I was trying to make. Speaker crossovers use different materials and different configurations to transmit the audio signal to the drivers. If what you were saying were true then all speakers and record players would have the same sound, correct? Are you saying that all capacitors, resistors, and board materials and configurations sound the same? In some cases, using certain capacitors and resistors. Example: using Jentzen Z-standard capacitors and a cheap wire wound resistors in a speaker crossover that has it's board traces made from 88% OFC copper will sound much worse, (worse being defined as much lower quality tone, imaging, soundstage, dynamics, detail, and clarity) compared to a crossover board using 99.999999% OFC traces and Mundorf Gold/Oil capacitors and Duelund cast resistors mounted onto it. I won't even get into the inductors, etc. on the board.

    These differences (between the above examples of crossover boards in speakers) are not imagined, fary-tale, "golden ear" etc., etc. differences. They are very real and obvious if you take the time to learn how to listen and pay attention to them. An oscillascope (as an example of a machine used to measure audio waves) will not pick up differences in imaging and soundstage. Why? It's not designed to do this. Your ears and consciousness obviously are, that's why people can hear the differences. This applies to both audio wires and crossover boards. Why are there differences? To a certain extent, the type metal, dialectric, and wire configuration (in and audio cable) and the crossover board used in the example above have a faster propagation of velocity than another crossover board, and audio cable. I realise there may be other reasons why there are differences as well, but we are talking about velocity of propagation here.

    Quote Originally Posted by Speedskater View Post
    I don't think that Oliver Heavyside had an oscilloscope way back in 1893.
    No, he didn't. He didn't have high resolution stereophonic audio either. The papaer you cited was also not written in 1893 by Oliver Heavyside. His work was only referenced. Again, this was for telephone lines and telegraph lines. Hardly the same as modern sterophonic audio cables using newer metals, dialectrics, and wiring configurations (as I referenced in my last post and above in this one). There are greater frequency responses, velocity of propagation, and resolution in newer cables. There are also things such as soundstage and imaging that a monophonic telephone lines didn't have in 1893.

    I hope I made my points complete and clear so you can understand them. I am interested in your thoughts about the possibility that oscillascopes and other measuring devices may not be able to pick up differences that a person's ears, and consciousness can. Please try to reply more thouroughly this time. Thank you again.
    Taken from a recent Audioholics reply regarding "Club Polk" and Polk speakers:

    "I'm yet to hear a Polk speaker that merits more than a sentence and 60 seconds discussion."

    "Green leaves reveal the heart spoken Khatru"- Jon Anderson

    "Have A Little Faith! And Everything You'll Face, Will Jump From Out Right On Into Place! Yeah! Take A Little Time! And Everything You'll Find, Will Move From Gloom Right On Into Shine!"- Arthur Lee

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