AES50 Cable?

M32 and X32 Digital Consoles
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GaryH
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Re: AES50 Cable?

Post by GaryH »

@RexBeckett Most interesting! Yet it still doesn't seem to be widely known. That makes the info from Midas regarding their Cat5E-100M even more ridiculous than it already is now some 7 years later. I can show more than a few areas in MT product documentation where there is still conflicting information regarding cable use. There is one place. The bottom line is, with the gear I own anyway, it may not be Cat5E (very likely NOT that) but it will always be good quality shielded cable, shielded rj45's bonded at both ends and MOST definitely with Ethercons. In my testing Ethercons without a doubt had the most dramatic effect. In Brian Wynne's testing it did as well but it really hit home seeing it first hand.
RexBeckett
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Re: AES50 Cable?

Post by RexBeckett »

GaryH wrote: Fri Jun 25, 2021 2:14 pm @RexBeckett Most interesting! Yet it still doesn't seem to be widely known. That makes the info from Midas regarding their Cat5E-100M even more ridiculous than it already is now some 7 years later.
I was intrigued by a comment in that prosoundweb discussion that shielded AES50 cables could introduce problems. As in: "My Midas tech does not recommend to use shielded cables because he knows some issues with them." I'm still trying to figure-out if there is some technical basis for this.

I have encountered this sort of vague recommendation from suppliers before. In some cases it seemed to translate as: "We don't recommend this type of product because we don't have any." ;)
curtbl
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Re: AES50 Cable?

Post by curtbl »

So I haven't done the research but interested which of the midas stage boxes are Opto Isolated the DL is not and neither is the M32. The lower end boxes on everyone's side seem not to be. Out of all the cut back in product to get a price point it seems that Opto's would have been a good thing to leave as part of the design.
I have actually thought about building opto isolators just for the reasons being discussed.C
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GaryH
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Re: AES50 Cable?

Post by GaryH »

@curtbl I had heard about those in another discussion and couldn’t remember the term opto to ask if that was possibly a factor :-) Glad you mentioned it….I know little about it but will now look it up.
RexBeckett
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Re: AES50 Cable?

Post by RexBeckett »

curtbl wrote: Fri Jun 25, 2021 3:54 pm So I haven't done the research but interested which of the midas stage boxes are Opto Isolated the DL is not and neither is the M32. The lower end boxes on everyone's side seem not to be. Out of all the cut back in product to get a price point it seems that Opto's would have been a good thing to leave as part of the design.
I have actually thought about building opto isolators just for the reasons being discussed.C
So did there used to be Midas Pro stageboxes with opto-isolated AES50 ports? I don't see that as a feature of any in the current range. The only optical network link appears to be HyperMac over fibre which is provided on the Pro6 and Pro9 consoles for connection to the DL371 Audio System Engine.

You could use a pair of KT DN9620 to run an AES50 link over fibre but it would be a fairly expensive solution - unless you needed the extended range.
Dan Mortensen
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Re: AES50 Cable?

Post by Dan Mortensen »

RexBeckett wrote: Fri Jun 25, 2021 3:37 pm
I was intrigued by a comment in that prosoundweb discussion that shielded AES50 cables could introduce problems. As in: "My Midas tech does not recommend to use shielded cables because he knows some issues with them." I'm still trying to figure-out if there is some technical basis for this.
The only circumstance that I've been able to figure out where it might be a problem is if your stage box was on one power source and the console was on another and there was a significant difference on the neutral to ground voltage for each.

For example, two buildings each on its own power transformer and with its own grounding system that were not interconnected. If one was at zero volts neutral to ground, and the other was at 20 volts or whatever, then the snake shield would be the equalizing path between them and current would flow. What would that do to the signal and to the mixer/stage box?

That was one of the things we were going to test at the Ethernet cable workshop 8 years ago or whenever that was, and I haven't gotten a round tuit since.

Of course, faulty wiring in the same facility on two different circuits could cause equally disturbing neutral/ground voltages, but then you've probably got other problems with the room, too. The two-building example is easier to picture, I think.
RexBeckett
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Re: AES50 Cable?

Post by RexBeckett »

Dan Mortensen wrote: Sat Jun 26, 2021 6:18 pm
RexBeckett wrote: Fri Jun 25, 2021 3:37 pm
I was intrigued by a comment in that prosoundweb discussion that shielded AES50 cables could introduce problems. As in: "My Midas tech does not recommend to use shielded cables because he knows some issues with them." I'm still trying to figure-out if there is some technical basis for this.
The only circumstance that I've been able to figure out where it might be a problem is if your stage box was on one power source and the console was on another and there was a significant difference on the neutral to ground voltage for each.

For example, two buildings each on its own power transformer and with its own grounding system that were not interconnected. If one was at zero volts neutral to ground, and the other was at 20 volts or whatever, then the snake shield would be the equalizing path between them and current would flow. What would that do to the signal and to the mixer/stage box?
That could well cause problems and even warm-up the AES50 cable. In those circumstances I would want to use a fibre link rather than just omitting the shield.

There was scattered discussion in 2013/2014 about a reputed flaw in the grounding schemes of some Pro products. It was claimed that connecting the shield at both ends of AES50 cables could result in an audible ground-loop if the units were powered from different points on the distribution circuit. There's nothing new about that situation, of course. It can happen with most types of audio equipment. Running power for the FOH console out from the stage usually helps.
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