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  1. #1
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    Sub's signal and AC power married.

    See pix,
    I have a 12" Velodyne sub, because I wanted a neat look so I have the Sub's signal and AC power cord spiral twisted together. A really bad ideal?
    FYI: I used a shielded Ethereal cable for the Sub LFE.

    Thanks.
    Attached Thumbnails Attached Thumbnails Sub's signal and AC power married.-dsc03317.jpg   Sub's signal and AC power married.-dsc03318.jpg   Sub's signal and AC power married.-dsc03319.jpg  

  2. #2
    Color me gone... Resident Loser's Avatar
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    The general rule of thumb...

    Quote Originally Posted by gjpham
    See pix,
    I have a 12" Velodyne sub, because I wanted a neat look so I have the Sub's signal and AC power cord spiral twisted together. A really bad ideal?
    FYI: I used a shielded Ethereal cable for the Sub LFE.

    Thanks.
    ...is that AC cords and signal leads should never run parallel nor in close proximity of each other...further, that when they must cross paths, they should do so at 90deg angles...based on that, I would say twisting them together is even a bigger no-no.

    Given that the end result is to lessen the possibility of 50-60Hz AC line frequency from impinging on the musical signal AND that a sub is designed to provide those lower frequencies, it would not seem to be a marriage made in heaven.

    Obviously there is greater need to be mindful of this when dealing with non-shielded (i.e. speaker wiring) than with coax, but I think in general it's a good rule to follow. as there may be other issues, such as heat, to contend with.

    jimHJJ(...sometimes neatness doesn't count...)
    Hello, I'm a misanthrope...don't ask me why, just take a good look around.

    "Men would rather believe than know" -Sociobiology: The New Synthesis by Edward O. Wilson

    "The great masses of the people...will more easily fall victims to a great lie than to a small one" -Adolph Hitler

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    If you repeat a lie often enough, some will believe it to be the truth...

  3. #3
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    Thanks,
    Here I go, off they come.
    Also, you'd see I TOO spiral twisted the AC exstension cord ( contend AV receiver, DVD player, VCR) with the reading light AC power cord. A big no no too?
    Thanks for reading.

  4. #4
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    Well...

    Quote Originally Posted by gjpham
    Thanks,
    Here I go, off they come.
    Also, you'd see I TOO spiral twisted the AC exstension cord ( contend AV receiver, DVD player, VCR) with the reading light AC power cord. A big no no too?
    Thanks for reading.
    ...AC is AC...the only legitimate argument I can pose is one of heat...you are probably better off allowing the cords to have their own "space" rather than twisting them together...of course, there are those "tweak-o-philes" among us who might have reasons beyond that of heat, citing the potential for RFI/EMI eminating from one unit's cord contaminating the purity of the AC sine wave into the others and vice-versa...If your reading light has a dimmer, there could be a problem in that regard but, cord proximity isn't really the issue in that case, just the fact that there is a dimmer involved would be problem enough..

    jimHJJ(...good luck...)
    Hello, I'm a misanthrope...don't ask me why, just take a good look around.

    "Men would rather believe than know" -Sociobiology: The New Synthesis by Edward O. Wilson

    "The great masses of the people...will more easily fall victims to a great lie than to a small one" -Adolph Hitler

    "We are never deceived, we deceive ourselves" -Goethe

    If you repeat a lie often enough, some will believe it to be the truth...

  5. #5
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    Quote Originally Posted by Resident Loser
    ...is that AC cords and signal leads should never run parallel nor in close proximity of each other...further, that when they must cross paths, they should do so at 90deg angles...based on that, I would say twisting them together is even a bigger no-no.

    Given that the end result is to lessen the possibility of 50-60Hz AC line frequency from impinging on the musical signal AND that a sub is designed to provide those lower frequencies, it would not seem to be a marriage made in heaven.

    Obviously there is greater need to be mindful of this when dealing with non-shielded (i.e. speaker wiring) than with coax, but I think in general it's a good rule to follow. as there may be other issues, such as heat, to contend with.

    jimHJJ(...sometimes neatness doesn't count...)
    My rule of thumb is exactly the opposite..it is, of course, entirely contrary to what would be expected, but it has served me quite well. So I explain..

    The sub signal cable and the line cord will form a ground loop. This loop will pick up all sorts of nasty pops, clicks, etc. Since this loop is not easily eliminated due to safety or practical considerations, I choose to minimize it. This I do by tightly joining the cables, twist and or mesh sleeving.

    It has proven so successful for me, that I have built a snake cable comprised of a 100 foot grounded extension cord cabled with a balanced mike run and an unbalanced line level feed run. This works very well in an industrial enviro.

    The only caveat I can think of would be larger draws through the cord...I pull about 20 watts along the extension cord (this being the denon 1800 and mixer draw), so cannot answer as to larger draws using this technique. It is good for external noise sources, but I don't know about internal ones.

    My recommendation would be keep them separate as you suggest, and if he gets lots of noise like pops and clicks or hum...then try twisting them together or taping them together as a solution to a real problem.

    Cheers, John

  6. #6
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    You should change your moniker...

    Quote Originally Posted by jneutron
    My rule of thumb is exactly the opposite..it is, of course, entirely contrary to what would be expected, but it has served me quite well. So I explain..Cheers, John
    ...to O.B. Difficult...Howya' been? Well, that certainly flies in the face of common practice...but I've really been limited to short runs, mostly with unshielded signal paths. Did you ever ID which coax was the culprit? My money would be on the unbalanced feed.

    When you say twist do you mean like a braid? A rope lay? Or does the PC form a helical coil around the coax?

    I would guess each one would have a different radiation pattern.

    jimHJJ(...be kind...)
    Hello, I'm a misanthrope...don't ask me why, just take a good look around.

    "Men would rather believe than know" -Sociobiology: The New Synthesis by Edward O. Wilson

    "The great masses of the people...will more easily fall victims to a great lie than to a small one" -Adolph Hitler

    "We are never deceived, we deceive ourselves" -Goethe

    If you repeat a lie often enough, some will believe it to be the truth...

  7. #7
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    Quote Originally Posted by Resident Loser
    ...to O.B. Difficult...Howya' been? Well, that certainly flies in the face of common practice...but I've really been limited to short runs, mostly with unshielded signal paths. Did you ever ID which coax was the culprit? My money would be on the unbalanced feed.

    When you say twist do you mean like a braid? A rope lay? Or does the PC form a helical coil around the coax?

    I would guess each one would have a different radiation pattern.

    jimHJJ(...be kind...)
    Doin well..lotsa kitchen work, the mitre is a ryobi.

    The issue for that long line setup was not a result of the coax. It was an issue with the building grounding and the stray fields. Any attempt at running audio through the auditorium using the existing cabling and power outlets ended up with hum and noise. The audio guy here ended up buying all wireless cabling or transformer isolators to get from the booth to the stage to the mikes to the mixing board..what a mess.

    Since I use my own personal system to support the science show, I did not have the patience, time, or money to resolve the hum and noise I get when I use the existing building wiring. So, I thunk out the problem, how the noises got into the system, and built my snake set to verify my thunking..it woiked.

    The DVD player and sound rack on the balcony get their power from the same outlet as the power amp on the stage, a 39 inch tv on the stage is also plugged into the same outlet as the amp. And, the video feed to the tv comes from the DVD, while the dvd audio goes into the sound board. Many loops, but yet no hum or noise..so far, so good.

    Cheers, John

  8. #8
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    I get it...

    ...eliminate the difference in ground potential as a source for problems...

    jimHJJ(...gotcha'...)
    Hello, I'm a misanthrope...don't ask me why, just take a good look around.

    "Men would rather believe than know" -Sociobiology: The New Synthesis by Edward O. Wilson

    "The great masses of the people...will more easily fall victims to a great lie than to a small one" -Adolph Hitler

    "We are never deceived, we deceive ourselves" -Goethe

    If you repeat a lie often enough, some will believe it to be the truth...

  9. #9
    Audio Hobbyist Since 1969 Glen B's Avatar
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    Quote Originally Posted by gjpham
    See pix,
    I have a 12" Velodyne sub, because I wanted a neat look so I have the Sub's signal and AC power cord spiral twisted together. A really bad ideal?
    FYI: I used a shielded Ethereal cable for the Sub LFE.

    Thanks.
    Not the best idea. Why not have an electrical outlet installed directly behind the sub ? Alternately you could route the cables thru some sort of wire management system that will hide them. See here for some options:
    http://cableorganizer.com/surface-raceways/#A

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