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<blockquote data-quote="Dan Mortensen" data-source="post: 92267" data-attributes="member: 2826"><p>Re: PNW AES Audio Over Ethernet Cables Workshop Moderator Conclusions v. 2.0</p><p></p><p><span style="font-size: 15px">Hi All,</span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px">We had our workshop on Saturday, and it went astonishingly well, managed to maintain audience interest for a full day, and we were able to at least partially disrupt the data transmission in an Ethernet cable. I written some personal conclusions that I drew from our experiences, and share them with you here.</span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px">Note that these are all my personal feelings, and in no way reflect the Audio Engineering Society, the Pacific Northwest Section, or anyone else.</span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px">A fuller meeting summary will soon appear on the PNW AES website in the Archives section. </span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><a href="http://www.aes.org/sections/pnw/pnwrecaps/" target="_blank">http://www.aes.org/sections/pnw/pnwrecaps/</a></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px">It is not there yet, and I don't know when it will be.</span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px">Dan</span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px">===================</span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">THESE CONCLUSIONS MAY ONLY APPLY TO THE SUPERMAC (AES-50 compliant) PROPRIETARY POINT-TO-POINT DIGITAL AUDIO CONNECTION TECHNOLOGY; relevance to other Ethernet-cable-based audio transport is neither proven nor alleged, except that measurement device results (in this case from a Fluke DTX-1800) will say whether or not a cable passes acceptability testing for use as an Ethernet CategoryX cable . We used Behringer X32 Digital Consoles and Behringer S16 Digital Snake heads for our tests.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">1) We were able to disrupt the data transmission of every cable we tried, including Cat5, Cat5e, Cat6, Cat6a, whether shielded (screened) or unshielded (unscreened) EXCEPT for the Belden 10GX24 Cat6a U/UTP. However, that cable does not have a robust outer jacket, and may not be suitable for portable live sound usage.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">2) The data transmission disruptions we were able to achieve at our event were of very short duration, as opposed to the disruptions I experienced on one occasion inadvertently and on another occasion on purpose with a specific 200' piece of Belden 7923A U/UTP. Those disruptions lasted as long as I kept pulling the cable and stopped only when I stopped pulling on the cable, and started again immediately when I pulled on the cable and stopped when I stopped pulling. Those disruptions also generated bursts of white noise from the audio outputs which lasted as long as the disruptions, and the data screens on the consoles blinked and sputtered simultaneously for the duration. I failed many other times to disrupt the data transmission when trying, using the exact same piece of cable. The disruptions at this event caused the screens to momentarily blink, and created "pops" from the audio outputs. I have no explanation for the discrepancy.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">3) The physical force required to disrupt the data transmission at our event was significantly greater than what I exerted on the two previously-described occasions. I have no explanation for this.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">4) The forces required to disrupt the data transmission are a combination of squeezing/pinching the cable while simultaneously pulling it through the pinching location. Objects used to create the pinching did not seem to be material-specific; we used parallel electrical wires and a wooden broom stick handle parallel to a length of metal conduit, all squeezed with one or two person's hands.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">5) We were also able to disrupt the data transmission by having 20 or more people stomping on the same piece of Belden 7923A cable while it laid on a flat hardwood floor. After that, we were able to disrupt by having one person stomp on the cable on the floor while the other people were not on it, but another person trying the same thing could not disrupt the data transmission. We did not try this technique with other cables. Note that this specific piece of Belden 7923A registered "PASS" on the Fluke DTX-1800 meter AFTER the abuse testing.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">6) The disruption of the data transmission can occur within a single pair, which we determined by stripping the jacket from the middle of a C2G CA19378 Cat5e U/UTP 150' cable and pinching and pulling each pair separately. All pairs exhibited the same behavior while disrupting data.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">7) We wrapped an inexpensive Richland E257448 Cat5e U/UTP 25' 40+ times around a 12" length of black-iron water pipe, and it still registered "PASS" on a Fluke DTX-1800 meter. From this, we conclude that CAT5e cables are likely to be unaffected by casual contact with or juxtaposition to random ferrous objects.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">8) Placing a relatively intense source of RF interference (AC cable to and from a barely-choked lighting dimmer and its 1KW lighting load) near, on, and across a Cat5e cable did not interfere with the SuperMAC data transmission.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">9) Things we learned from our Experts:</span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> A) The solid copper wire in today's CATegory cables is vastly superior to previous generations of solid copper wire in terms of resistance to repeated flexing. Degradation of wire due to normal repeated use is much less of an issue than we'd expect.</span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> B) From an American perspective, the European obsession with shielding (screening) cables is overblown, and a response to a problem that has not been demonstrated to exist at a significant enough level to need a solution. Unshielded (unscreened) cables work just fine in almost every application, except for specific environments with very high levels of specific RF interference. The vast, vast, vast majority of users will not benefit from using shielded (screened) cables, nor will they suffer ill effects from not doing so. That said, there are <strong>specific legal requirements </strong>to use shielded cable in certain situations in many legal jurisdictions, and the wise user will <strong>pay close attention to those requirements</strong>.</span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> C) The RJ-45 connector was designed for a very different usage than with Category cables, and as the desired network speed increases into the future, it will be unsuited for those fast, fast speeds. At the existing ragged edge, it may be already unsuited, and performance may suffer.</span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> D) Many RJ-45 connectors are unsuited for use with shielded (screened) connectors, even those apparently designed for the purpose, and the grounding connection, especially for shielded cables without a drainwire, seems tenuous at best when compared to a soldered connection.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">10) To extrapolate from #9A above, we drove over the middle of a 137' Belden Brilliance Video Low Skew RGB7988P Cat5e U/UTP cable, placed on a solid hardwood floor and connected between console and snakehead, with both of the front solid rubber tires of a scissor lift having a stated weight of over 900# per wheel</span><span style="font-family: 'Times-Roman'">, so there was damage in two places on the cable</span><span style="font-family: 'Times-Roman'">. This driving over was repeated at least 20 times. It permanently changed the shape of the cable from round to very, very flat, but did not disrupt the data transmission at all, and the damaged cable still measured "PASS" on the Fluke DTX-1800 meter when removed and measured. This passing grade says nothing about the life of the cable, but it does indicate that you are unlikely to have immediate data transmission disruption from driving over the cable with a vehicle. We were going to test another cable by driving over it with a 10,000# GVW 14' box truck's tires, but felt that the scissor-lift test showed that we were unlikely to create damage using inflated rubber tires.</span></span></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">11) Things we forgot/didn't get to:</span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> A) All Ethernet circuits balance each twisted pair, and the balancing is (always?) done with surprisingly high quality balancing transformers on each end of each pair, thus providing galvanic isolation between the devices at each end. </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> B) We intended to (but didn't) test the effect of having vastly different yet realistic ground potentials on </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> i) the AC supplied to the console </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> ii) the AC supplied to the snake head </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">and then comparing the effect on data transmission/audio quality output when the two devices are connected by U/UTP and then F/UTP cables.</span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> C) We only used the Behringer consoles to examine data disruption. We did have a Roland M400 digital console and snake head present, but </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> i) there was no one advocating its use, </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> ii) I was told it exclusively uses a crossover Ethernet cable, </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> iii) the disruptive physical forces we were using could permanently degrade a cable, </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> iv) I didn't want to wreck the cable that came with it or spend time figuring out how to use one of our sample cables, </span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"> v) ultimately time disappeared before we could test it. There were no other Audio-Over-Ethernet-Cable devices present.</span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'"></span></span></span></p><p><span style="font-size: 15px"><span style="color: #000000"><span style="font-family: 'Times-Roman'">YMMV.</span></span></span></p></blockquote><p></p>
[QUOTE="Dan Mortensen, post: 92267, member: 2826"] Re: PNW AES Audio Over Ethernet Cables Workshop Moderator Conclusions v. 2.0 [SIZE=4]Hi All, We had our workshop on Saturday, and it went astonishingly well, managed to maintain audience interest for a full day, and we were able to at least partially disrupt the data transmission in an Ethernet cable. I written some personal conclusions that I drew from our experiences, and share them with you here. Note that these are all my personal feelings, and in no way reflect the Audio Engineering Society, the Pacific Northwest Section, or anyone else. A fuller meeting summary will soon appear on the PNW AES website in the Archives section. [URL]http://www.aes.org/sections/pnw/pnwrecaps/[/URL] It is not there yet, and I don't know when it will be. Dan =================== [/SIZE][SIZE=4][COLOR=#000000][FONT=Times-Roman]THESE CONCLUSIONS MAY ONLY APPLY TO THE SUPERMAC (AES-50 compliant) PROPRIETARY POINT-TO-POINT DIGITAL AUDIO CONNECTION TECHNOLOGY; relevance to other Ethernet-cable-based audio transport is neither proven nor alleged, except that measurement device results (in this case from a Fluke DTX-1800) will say whether or not a cable passes acceptability testing for use as an Ethernet CategoryX cable . We used Behringer X32 Digital Consoles and Behringer S16 Digital Snake heads for our tests.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]1) We were able to disrupt the data transmission of every cable we tried, including Cat5, Cat5e, Cat6, Cat6a, whether shielded (screened) or unshielded (unscreened) EXCEPT for the Belden 10GX24 Cat6a U/UTP. However, that cable does not have a robust outer jacket, and may not be suitable for portable live sound usage.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]2) The data transmission disruptions we were able to achieve at our event were of very short duration, as opposed to the disruptions I experienced on one occasion inadvertently and on another occasion on purpose with a specific 200' piece of Belden 7923A U/UTP. Those disruptions lasted as long as I kept pulling the cable and stopped only when I stopped pulling on the cable, and started again immediately when I pulled on the cable and stopped when I stopped pulling. Those disruptions also generated bursts of white noise from the audio outputs which lasted as long as the disruptions, and the data screens on the consoles blinked and sputtered simultaneously for the duration. I failed many other times to disrupt the data transmission when trying, using the exact same piece of cable. The disruptions at this event caused the screens to momentarily blink, and created "pops" from the audio outputs. I have no explanation for the discrepancy.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]3) The physical force required to disrupt the data transmission at our event was significantly greater than what I exerted on the two previously-described occasions. I have no explanation for this.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]4) The forces required to disrupt the data transmission are a combination of squeezing/pinching the cable while simultaneously pulling it through the pinching location. Objects used to create the pinching did not seem to be material-specific; we used parallel electrical wires and a wooden broom stick handle parallel to a length of metal conduit, all squeezed with one or two person's hands.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]5) We were also able to disrupt the data transmission by having 20 or more people stomping on the same piece of Belden 7923A cable while it laid on a flat hardwood floor. After that, we were able to disrupt by having one person stomp on the cable on the floor while the other people were not on it, but another person trying the same thing could not disrupt the data transmission. We did not try this technique with other cables. Note that this specific piece of Belden 7923A registered "PASS" on the Fluke DTX-1800 meter AFTER the abuse testing.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]6) The disruption of the data transmission can occur within a single pair, which we determined by stripping the jacket from the middle of a C2G CA19378 Cat5e U/UTP 150' cable and pinching and pulling each pair separately. All pairs exhibited the same behavior while disrupting data.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]7) We wrapped an inexpensive Richland E257448 Cat5e U/UTP 25' 40+ times around a 12" length of black-iron water pipe, and it still registered "PASS" on a Fluke DTX-1800 meter. From this, we conclude that CAT5e cables are likely to be unaffected by casual contact with or juxtaposition to random ferrous objects.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]8) Placing a relatively intense source of RF interference (AC cable to and from a barely-choked lighting dimmer and its 1KW lighting load) near, on, and across a Cat5e cable did not interfere with the SuperMAC data transmission.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]9) Things we learned from our Experts:[/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] A) The solid copper wire in today's CATegory cables is vastly superior to previous generations of solid copper wire in terms of resistance to repeated flexing. Degradation of wire due to normal repeated use is much less of an issue than we'd expect.[/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] B) From an American perspective, the European obsession with shielding (screening) cables is overblown, and a response to a problem that has not been demonstrated to exist at a significant enough level to need a solution. Unshielded (unscreened) cables work just fine in almost every application, except for specific environments with very high levels of specific RF interference. The vast, vast, vast majority of users will not benefit from using shielded (screened) cables, nor will they suffer ill effects from not doing so. That said, there are [B]specific legal requirements [/B]to use shielded cable in certain situations in many legal jurisdictions, and the wise user will [B]pay close attention to those requirements[/B].[/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] C) The RJ-45 connector was designed for a very different usage than with Category cables, and as the desired network speed increases into the future, it will be unsuited for those fast, fast speeds. At the existing ragged edge, it may be already unsuited, and performance may suffer.[/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] D) Many RJ-45 connectors are unsuited for use with shielded (screened) connectors, even those apparently designed for the purpose, and the grounding connection, especially for shielded cables without a drainwire, seems tenuous at best when compared to a soldered connection.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]10) To extrapolate from #9A above, we drove over the middle of a 137' Belden Brilliance Video Low Skew RGB7988P Cat5e U/UTP cable, placed on a solid hardwood floor and connected between console and snakehead, with both of the front solid rubber tires of a scissor lift having a stated weight of over 900# per wheel[/FONT][FONT=Times-Roman], so there was damage in two places on the cable[/FONT][FONT=Times-Roman]. This driving over was repeated at least 20 times. It permanently changed the shape of the cable from round to very, very flat, but did not disrupt the data transmission at all, and the damaged cable still measured "PASS" on the Fluke DTX-1800 meter when removed and measured. This passing grade says nothing about the life of the cable, but it does indicate that you are unlikely to have immediate data transmission disruption from driving over the cable with a vehicle. We were going to test another cable by driving over it with a 10,000# GVW 14' box truck's tires, but felt that the scissor-lift test showed that we were unlikely to create damage using inflated rubber tires.[/FONT][/COLOR][/SIZE] [SIZE=4] [/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]11) Things we forgot/didn't get to:[/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] A) All Ethernet circuits balance each twisted pair, and the balancing is (always?) done with surprisingly high quality balancing transformers on each end of each pair, thus providing galvanic isolation between the devices at each end. [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] B) We intended to (but didn't) test the effect of having vastly different yet realistic ground potentials on [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] i) the AC supplied to the console [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] ii) the AC supplied to the snake head [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman]and then comparing the effect on data transmission/audio quality output when the two devices are connected by U/UTP and then F/UTP cables.[/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] C) We only used the Behringer consoles to examine data disruption. We did have a Roland M400 digital console and snake head present, but [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] i) there was no one advocating its use, [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] ii) I was told it exclusively uses a crossover Ethernet cable, [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] iii) the disruptive physical forces we were using could permanently degrade a cable, [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] iv) I didn't want to wreck the cable that came with it or spend time figuring out how to use one of our sample cables, [/FONT][/COLOR][/SIZE] [SIZE=4][COLOR=#000000][FONT=Times-Roman] v) ultimately time disappeared before we could test it. There were no other Audio-Over-Ethernet-Cable devices present. YMMV.[/FONT][/COLOR][/SIZE] [/QUOTE]
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