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Thread: AES50 and ground loop potential

  1. #71
    Quote Originally Posted by Keith Broughton View Post
    Would the potential for ground loops, when using STP, only be applicable if the equipment (X32 and S16) has the "dreaded pin 1 problem"?
    The pin 1 problem, popularized and AFAIK discovered by the late, great Neil Muncy, was caused by cheapo manufacturers using circuit boards with too small foil trace to connect pin 1 ultimately to the chassis, and was completely eliminated by an actual wire or very large foil traces to connect to chassis.

    He conclusively demonstrated that there could be a huge voltage induced on the mic cable/line out cable shield by EMF interference from a variety of sources, and I'm happy to report that he raised his eyebrows at the amount of RF BS that was generated by a little portable lighting dimmer I had when he spoke to our AES Section. That was a meeting that started at 7:30pm, and he had us so entranced and fascinated that when we stopped to look at the time it was approaching or just beyond midnight. I will never forget that night, and it changed my thinking and actions forever.

    The important part about the induced voltage is that because it is so large (thousands of volts, as we've seen ITT), the foil trace if too small acts as a resistor and there is voltage across it when there should be zero voltage, and that makes hum in audio. An actual wire of almost any size does not do that, nor, apparently, do large foil traces.

    It would be interesting to know how the AES50 connector makes its chassis connection. Is that something that the final device manufacturer designs in, or is it somehow occurring as a result of being attached to the chassis. I would hope a combination of both, but it would be interesting to know.

    The consensus at our Workshop was that, compared to how we treat grounding in audio, the RJ45/Ethercon grounding method was pretty haphazard and variable rather than solid and conclusive. But apparently it is enough to work in that application.

    And yes, that is me, although I think I'm "that" Dan instead of "the" Dan. I'm sure there are other Dans who think of themselves as "the", and I wouldn' claim the title.

  2. #72
    Quote Originally Posted by Glenn Adams View Post
    Dan Mortensen; Going to respond to a bunch of posts in one post so you don't see a bunch of posts in a row from me.
    I've done shielded with one end lifted and it's the same as UTP. Not sure what the second sentence means.

    I was referring to both ends of a cable, my lift, IF needed, was made at the FOH console. I would change that in my current setup to the stage end of the cable since it does not have to exposure to people touching as often.
    That is actually almost worse, as Brian showed that sparking a microphone connected to the S16 also caused an interruption. It's in his video.


    Quote Originally Posted by Glenn Adams View Post
    To do penance for your deeds, you can use your fancy test equipment to confirm that the X32 and S16 do indeed have transformers on the Ethernet connectors, and report back here your findings and methodology.
    I accept, but I normally just look for them on the NIC
    Thanks, looking forward to your results.

    What's the NIC?

    Quote Originally Posted by Glenn Adams View Post
    I am not always right. I scratch my head at least once a weeks and say, dang, never saw that happen before. I am willing to admit wrongness. The sparkler was interesting but I would not subject equipment to this test since it can stress internal electronic components
    .
    [/QUOTE]

    If discharging static from a person's body to the electronic device is not damaging, and I hope gear is designed to ignore that kind of thing, I don't see how the sparker is worse. If the gear cannot ignore that kind of thing, it is a cause for alarm, as has been shown by the response to it occurring in the X32.

    BTW, I really envy you having a DTX-1800. I had one for a few weeks on loan from Fluke before my workshop, and being able to precisely and definitively answer the question "Is this a good cable" was invaluable. Not invaluable in the same way that $9000 US in my bank account was valuable, though.

  3. #73
    Quote Originally Posted by Dan Mortensen View Post
    That is actually almost worse, as Brian showed that sparking a microphone connected to the S16 also caused an interruption. It's in his video.




    Thanks, looking forward to your results.

    What's the NIC?
    Technically it is just an older PC network card, called Network Interface Card, but we refer anything on the other side of the RJ45 as the NIC, or Network Interface Connection. The electronic parts that carry Ethernet inward.
    If discharging static from a person's body to the electronic device is not damaging, and I hope gear is designed to ignore that kind of thing, I don't see how the sparker is worse. If the gear cannot ignore that kind of thing, it is a cause for alarm, as has been shown by the response to it occurring in the X32.
    good to know, thanks, I'll let it be

    BTW, I really envy you having a DTX-1800. I had one for a few weeks on loan from Fluke before my workshop, and being able to precisely and definitively answer the question "Is this a good cable" was invaluable. Not invaluable in the same way that $9000 US in my bank account was valuable, though.[/QUOTE]
    It belongs to my company but spends most of its time in a cabinet in my lab. Got a couple of TDR's also, one for fiber. Prices and size have been coming down for these, we have one older rack model that was 40k and the first portable that was 25K. I now use a Fluke model that fits in a shirt pocket for 1k but is just a monitor. It covers 95% of what we need weekly. Pays to work for a fortune 400 company cause I can afford 9k either .

    Let me bounce this one off you since you have way more hands on of AES50 than I.
    Why does this test ( sparker ) drop com when normal Ethernet would truck thru?
    Is it a combination of clock and data using all 4 pairs? Most current Ethernet connections only use 2 unless PoE or Gigabit Etherchannel is used? How does Dante handle something like this test?
    AES50 needs to go fiber.
    Last edited by Glenn Adams; 08-02-2014 at 06:05 PM.

  4. #74
    Quote Originally Posted by Glenn Adams View Post
    Let me bounce this one off you since you have way more hands on of AES50 than I.
    Why does this test ( sparker ) drop com when normal Ethernet would truck thru?
    Don't know why, only know that it does under certain conditions and doesn't under one condition. There was speculation that it was a poor design on a daughter card (whatever that is), and maybe I don't remember that brief discussion very well. Never heard anything from Behringer about it. They have never commented about the issue AFAIK.

    Quote Originally Posted by Glenn Adams View Post
    Is it a combination of clock and data using all 4 pairs? Most current Ethernet connections only use 2 unless PoE or Gigabit Etherchannel is used?
    See above.

    Quote Originally Posted by Glenn Adams View Post
    How does Dante handle something like this test?
    Sorry, I don't know Dante at all. I literally know nothing about it and don't have anything that uses it.

    Quote Originally Posted by Glenn Adams View Post
    AES50 needs to go fiber.
    That isn't in the spec, is it? The spec calls for high quality cable, as has been pointed out here. Doesn't fiber have its own problems?

    Sorry to not be more helpful.

  5. #75
    Quote Originally Posted by Dan Mortensen View Post
    That isn't in the spec, is it? The spec calls for high quality cable, as has been pointed out here. Doesn't fiber have its own problems?

    Sorry to not be more helpful.
    Yes- but no ground loops, no ESD, and no dang RJ45.
    The daughter board is a circuit board plugged into a motherboard. Chances are that it is the board with the NIC.
    How is it that you know so much about the cable and not what is on the other side of what it is plugged into?

  6. #76
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    The "problem" with AES50 is that it is a low latency stream with a very strict clock requirement.
    Latency: 4 samples

    Ethernet can easily have a 10% packet loss without you ever noticing, and doesn't have the strict clocking.

    Dante relies on Ethernet protocol, and for that reason have built in latency to allow for packet transfer and to some extent retransfer of lost packets.
    Latency: 64-512 samples

    Fibre is expensive, a tour grade 100m cable can easily cost around €1000, and you'd probably have to add €300-500 to the price of each device. Add to that the inconvenience of always having to carry (and deploy) a spare cable, laying down cable guards etc.

  7. #77
    You're forgetting a few things. AES50 is a time sensitive protocol meaning that it has a clock sync and can't re-transmit lost packets as such.

    TCP/IP as opposed to AES50 (I'm saying TCP/IP, Not Ethernet, please note Ethernet refers to the physical layer of connections only, nothing about what is actually going on with it.) was designed for high-latency environments, it can handled drop packets, collied packets and do just fine.

    Also When you say AES50 should use Fiber instead of ethernet again. Ethernet is a means of connecting things. If AES50 only specifics ethernet rather than CAT5e or CAT6 cable then it can in fact run on Fiber fine. Both Fiber and CAT5/6 are means that can be used in ethernet (ethernet does not imply CAT5/6 or an RJ45).

    Fiber will also be more expensive investment and will need to be replaced more often, It's glass rolling it up it will have the chance to be broken often. Fiber can't do sharp curves or bends, the glass inside can easily break rendering it useless. It's superior for some situations in networking with AES50 it would really only be good in installed situations.

    If you'd just fix your grounding system this wouldn't be any issue, and grounding issues will cause problems for other things. So why just look for a way to Mask the problem instead of fixing the root cause?

  8. #78
    Yes Jason, all true.
    For installation it can't be beat. On the road it is getting better, but any cable it prone to physical damage. Fiber being the most fragile of these, and the RJ45.
    Also multimode fiber and it's converters are very inexpensive and just fine for links lengths like this. Single mode is coming down but the converters are still ugly.

    We just used a direct burial underground system from Corning that has 12 single mode strands in one connector no bigger than an XLR.
    It, the cable outside the armor, was flexible enough for road use. Expensive, but not for Clair.

  9. #79
    By the way, the Ethercon Outshell portion on the X32 consoles is connected to the EGC, the Casing etc. But the Shielding connector inside the RJ-45 is not, It's an open circuit on the right side of the RJ-45 on the Left side it is fully connected to ground.
    the P16 RJ-45 tabs are grounded on both sides. Wonder if this was a design flaw?

  10. #80
    Quote Originally Posted by Jason Finnigan View Post
    By the way, the Ethercon Outshell portion on the X32 consoles is connected to the EGC, the Casing etc. But the Shielding connector inside the RJ-45 is not, It's an open circuit on the right side of the RJ-45 on the Left side it is fully connected to ground.
    the P16 RJ-45 tabs are grounded on both sides. Wonder if this was a design flaw?
    I have not seen the connection inside yet, but most manufactured devices may have a place to solder on both sides to a jack but only one side needs to be connected. Only if high current is there would it need to be connected. The ground traces are normally generous enough. Signal traces keep getting bonier and bonier.

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