AES/EBU coax cables sensitivity to cable length? - diyAudio
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Old 11th August 2006, 03:43 PM   #1
miksin is offline miksin  Finland
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Default AES/EBU coax cables sensitivity to cable length?

Hi,

I am mostly concentrating in questions considering tube and analogue gear and am quite ignorant in questions of digital realm so I think i better ask the following: How sensitive is AES/EBU 110-ohm coaxial cable to the lenght of the cable?

I think I must rearrange my set-up a little due some WAF-issues and I am thinkin to build a separate wall shelf for sources, CD and LP. That solution just requires some 3 to 4 metres long AES/EBU coax cable from sources to the X-over. ( I am running an active 3-way system).

So, in your opinion, is a three metres lenght an issue with such cable or not?


...and thanks for reading this far

Mika
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Old 11th August 2006, 04:01 PM   #2
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It will depend on the application (digital or analog) and the capacitance per foot and the frequency range. If you've got decent source impedance and are using it for analog, 3m is no problem. If it's for digital transmission and is properly terminated, no problem. However for long (>20m) digital transmission, I think it's safer to run 75 ohm coax. ....assuming there aren't ground loop issues. There was a story of Cirque du Solie running a long run of 110 ohm AES/EBU. By the time the time the signal arrived at thedigital input speakers, the eye was almost completely closed due to HF attenuation. This caused no sound. They swapped over to 75 ohm coax, looked at the eye and it was large and in charge. So, low low capacitance 110 ohm cable will maximize your transmission length (if digital) Your "shorttish" lengths (<20m) should present no problem.
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Old 11th August 2006, 04:10 PM   #3
miksin is offline miksin  Finland
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Application is digital, as follows: from CD:s S/pdif output to S/pdif-AES/EBU-converter, and from there to the XO:s input.(AES/EBU digital). Then LP again will need separate A/D converter, (hopefully with AES/EBU out ), and from there to the XO.
The l"long" cable runs to the XO.
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Old 11th August 2006, 05:20 PM   #4
gmarsh is offline gmarsh  Canada
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With the proper cable (belden brilliance, etc) and a decent drive strength on the sending end, AES can run 100m or more... I've done it.
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Old 12th August 2006, 03:58 PM   #5
miksin is offline miksin  Finland
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So it seems that it it gnerally agreed that if decent quality cable and source used AES/EBU coaxial cable is pretty unsensitive to cable length, at least in that 4 to 5 metres range. OK?
That's what I also thought.

Anyway, there are not much such cables available ready made, so I suppose I got to make some welding.

How, and with which kind of cable are xlr-connectors supposed to connect to cable? Pins 1,2 and 3? What connects to what?

...I am pretty used to make XLR-RCA-cables, but as I told, my knowledge in digital worls in about zero

and thaks again!

Mika
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Old 12th August 2006, 04:05 PM   #6
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Here you go:
http://www.aphex.com/pdf/2020MKII/Aphex_2020_chap09.PDF
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Old 12th August 2006, 06:00 PM   #7
miksin is offline miksin  Finland
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...Thanks, that made some great reading of problems of low-resolution digital audio. Again am happy to havin a good LP-player

Howsoever, from exellent white papers of Rane (Thanks, guys!) I found something.

Is AES/EBU simply pins 1 and 3 to ground and 2 to signal?
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Old 12th August 2006, 10:07 PM   #8
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Quote:
Is AES/EBU simply pins 1 and 3 to ground and 2 to signal?
No, not normally. If it's run in differential mode (it should be) Pin 1 = ground, Pin 2 = +, and Pin 3 = -. Running in differential mode is one of the prime reasons to choose AES/EBU.
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Old 12th August 2006, 11:12 PM   #9
gmarsh is offline gmarsh  Canada
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The AES cable you're using should be a single shielded twisted pair.

At each end, connect the twisted pair to pins 2 and 3, and connect the cable shield to the connector shield. Leave pin 1 unconnected.
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Old 15th August 2006, 12:16 PM   #10
tubenut is offline tubenut  South Africa
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I use Apogee Wyde Eye AES/EBU +/- 3 Metres no probs. It is avaialble per metre here (Cheaply, less then a 1/10 of terminated USD price) and with some Nuetrik XLRs it is not for off the Megabuck cables to my flaps on the side of my head.....
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