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Author Topic: AES cables System Notices Forum Watchdog / Soup Nazi Posts: 215 Registered: Apr 2004 posted 11-25-2017 05:32 AM                 It has been 2793 days since the last post.  |  IP: Logged Juan Jose Garcia Calvo Film Handler Posts: 64 From: Pedrajas de San Esteban, Spain Registered: May 2003 posted 11-25-2017 05:32 AM                     About the 110Ohms AES required cable impedance... What about the DOREMI servers getting out the AES out through an RJ45 and using CAT cables? We are using this to send the 4 AES channels to a Dolby DMA8Plus without problems (using a supplied RJ45 to DB25 adapter) . Are we lucky maybe?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-25-2017 06:26 AM                     A fortunate characteristics of CAT5e cable is its intrinsic impedance is about 100 ohms, which is in the range of AES. Note, if AES3 audio is on the cable, the cable should be shielded. It is a noisey signal.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 11-25-2017 07:33 AM                     Shielded to keep noisy signal in and avoid interference to other signals, or to protect signal from external interference?  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 11-25-2017 08:36 AM                        Both, if the audio wires are running alongside others (which they usually are). We use cat6 shielded, with RJ45 to DB25 adapters or an Odyssey board, depending on the application, at either end that doesn't have RJ45 jacks. This has the added advantage that if the audio processor or audio source (media block, IMB or IMS) is changed for something with a different jack configuration later on, you would only need to replace or remove the converter - no reterminating the cables needed.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-25-2017 06:44 PM                     Nah, I make my own cables of the right type and ends. A very high percentage of our installations are Surround 7.1 and that normally means getting pair 6 grouped over to pairs 1-3. I can generally make the ends cheaper than an Odyssey board. It all depends on the installation and what I want to do and what equipment is involved as to whether I budget in the Odyssey board(s). I've found zero reason to fool with CAT6 for AES cable. It is thicker, costs more, harder to work with, takes longer to terminate (increasing its cost). I tend to use CAT6 for the "Media" network and that is about it.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 12-01-2017 08:45 AM                     quote: Steve Guttag I've found zero reason to fool with CAT6 for AES cable. It is thicker, costs more, harder to work with, takes longer to terminate (increasing its cost). I tend to use CAT6 for the "Media" network and that is about it. Do you mean vs. Cat5, or vs. the purple cable? I assume you mean vs. Cat 5, because Cat6 certainly isn't thicker or harder to work with than the purple cable! Just wanted to clarify.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 12-01-2017 09:10 AM                     Than CAT5E. Proper AES cable is best in terms of signal transmission and shielding (all pairs are shielded and there is an overall shield) but CAT5e cable is "close enough" in impedance that we have not had issues with signal transmission in typical cinema applications. I'd say we use CAT5e over Belden AES cable about 9:1, perhaps closer to 50:1 now. There are times with AES snake cable works out better for the installation (being able to break the pairs out to different locations and what not or for the better shielding). Honestly though, we've made so many DB terminations that working with AES cable isn't a biggie either.  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 12-02-2017 03:03 PM                        Note that EBU Tech. 3250-E - Third edition from 2004 states in Appendix 2: AES/EBU signals on Structured Wiring There is an increasing use of structured wiring for carrying AES3 signals. Notwithstanding clause 6.1, the practice has been shown to be viable on Category 5 unscreened pairs, meeting EMI requirements, and offering transmission up to 400 metres overall unequalised, or 800 metres equalised, at 48 kHz frame rate. For a satisfactory outcome, this practice should only be used where the whole length of the connection uses Category 5 UTP (Unscreened Twisted Pair) cable, including that which is installed and any flexible leads (equipment cords), and that the connection is unscreened for the whole length. Alternatively, the whole length of the connection should use Category 5 STP (Screened Twisted Pair), and the connection should be screened for the whole length. Care should be taken in design of the interface to provide adequate balance on the twisted pair within the Cat.5 cable. Using RJ45 connectors, conventionally wired, current practice favours the use of pins 4 and 5 for AES/EBU signals (separating them from ATM signals on the same cable). Pins 3 and 6 are the preferred second pair. Note that, for full protection, the interface may have to withstand power voltages specified to support network equipment, and the use of transformers and blocking capacitors on the AES/EBU interface is strongly recommended. Suggested practice: while the interface is by definition insensitive to polarity, for the purposes of constructing adaptors, XLR Pin 2 should be connected to RJ45 Pin 5 (or other odd-numbered pin), XLR Pin 3 should be connected to RJ45 Pin 4 (or even-numbered pin). ================ We have run tests with four AES/EBU pairs in CAT5 unshielded cable with a length of 1,000 feet (less than the 400 meters specified above) with no issue. In addition, we have found Ethernet magnetics suitable for AES/EBU. This works well since Ethernet magnetics are more common and less expensive than transformers designed for AES/EBU. Also, you can get RJ45 and dual RJ45 connectors with internal magnetics saving on cost and board space. Harold  |  IP: Logged

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