AES/EBU over twisted pair

[Yorkie]

Looking to run AES/EBU over ~40m in an install where we're already pulling in Cat5e and Cat6 UTP. Should we look to put in STP instead? 

[J Pearce]

We often run our d&b D20 amps on AES over CAT5/6. We use the ratsound breakout boxes at present, but are planning on building a more custom patchbay. I think we're only using UTP (or at least only using UTP patches at either end), on a run that's probably 20m or so (maybe more via the trunking). Works great, and hasn't shown any issues.

AES3 (AES/EBU) on XLR is a balanced topology, apparently often implemented using RS422 transceivers. Some may be transformer isolated (EBU spec) and not need a ground, some may not and by spec should probably have a ground reference to ensure the line voltage does not exceed the common mode rejection of the receiver.

If you're pulling cable and can afford the jump I'd usually spec FTP or STP over UTP. It's much easier to lose a shield if it's causing issues than it is to gain one when its absence is causing issues.

[Brian]

Anyone remember Canford's AES/EBU over wet string demo? 

[p.k.roberts]

Yes I do - it was only over about 2 feet though as I recall ...

[Simon Lewis]

We are using "AES/EBU" (apparently called AES3 these days 😉 ) over about 50m of shielded CAT5e and the very cheap but quite well made Ssnake CAT adapters ( https://www.thomann.de/gb/the_sssnake_cat_snake_3mc.htm  ). We used STP as the same set of cable runs are also for DMX and some tie lines, so could be used for mics needing phantom power. 
Everything works fine....

 

[Hockeybod]

The terminology is confusing and there's a good guide here FAQ: What are FTP cables | Eland Cables

If it's a permanent installation, given the price difference why would you not use at least Cat 6e or even Cat 7 with shielded connectors? Admittedly foil shielding doesn't like being bent and is usually thicker, but you're only going to do this once so why not over-spec?

I've just installed a dual 40m permanent 6e cable run with shielded RJ45 faceplates at the school we use for performances. It worked perfectly at our last show and we had always had problems with drop-out using an extension reel, even a good quality one with Ethercon connectors.

On the subject of Ethercon, although they seem secure some sockets are still very prone to drop out with even a small movement. I have found that filling the back of the connector including the chuck and boot with silicon sealant or epoxy resin eliminates nearly all movement once it's set. It means they can't be re-used but they're cheap enough.