Topic: AES--->coax rca cable

[muj]

hey now,
i would like to add an extra digi output cable to feed another recorder from my v3.

i'm planning on using the AES  output.
has anyone of you forum members used aes-->coax/spdif cable with the v3?
and where's the best place to buy iy or had it made.


thanks in advance.

[Brian Skalinder]

hey now,
i would like to add an extra digi output cable to feed another recorder from my v3.

i'm planning on using the AES  output.
has anyone of you forum members used aes-->coax/spdif cable with the v3?
and where's the best place to buy iy or had it made.


thanks in advance.

I've run AES1 (consumer) > coax/SPDIF RCA out.  No need for the impedance transformer IME.  I made my own cables with Neutrik connectors and Canare cable, so not sure where to pick one up retail.

[muj]

thank you Brian.

[Tim]

www.kindkables.com

[dmonterisi]

hey now,
i would like to add an extra digi output cable to feed another recorder from my v3.

i'm planning on using the AES  output.
has anyone of you forum members used aes-->coax/spdif cable with the v3?
and where's the best place to buy iy or had it made.


thanks in advance.

I've run AES1 (consumer) > coax/SPDIF RCA out.  No need for the impedance transformer IME.  I made my own cables with Neutrik connectors and Canare cable, so not sure where to pick one up retail.

i simply do not understand the significance of 110 ohm v. 75 ohm cable here...it's a little bit surprising that you've had no issues not using an impedence transducer thingamajig.  i have one that i've used to be safe.  i wonder what problems are theoretically possible in this arrangement?

[marc0789]

no problems aes>sony stock 7 pin or oade active>m1 from the minime.

[John R]

i use aes2>coax for my dap1, aes1>coax for patchers, and coax >coax for patchers

[MattD]

Damon, not sure how into the physics you are, or anyone else on this board, but I found this to be a good read on impedence. It answers your question and pretty much any other one on the subject.

http://www.epanorama.net/documents/wiring/cable_impedance.html


(edited to fix horrible grammar)

[dmonterisi]

matt, you should only link to pages written in English.  

[MattD]

What, not everyone speaks Engineer? This is why I need an engineering job rather than a consulting job - I'll be a lot more 'normal' if I can get it out at work.

To answer your question (in English), So long as the run is short, meaning that it's shorter than a large fraction of the wavelength of the particular frequency it's carrying, there should be no audible effect on having a small impedence mismatch. This is why you can also use a foot or two of mic cable in a pinch to replace AES cable. I forget what the particular transmission frequency of SPDIF is, but that should be easy to find on another site that's probably also not written in English.

A mismatch in impedence from one end to the other will cause reflections in the cable. Depending on how severe this is, this will "damage" the signal so that your deck will not lock to the output of your A/D. Impedence matching sends all of the transmitted signal into the receiver so that there are no reflections.

The best description from the page I linked to is quoted below:

Why is characteristic impedance important in data transmission?
If a cable is terminated in its matching characteristic impedance you can't tell from the sending end that the cable is not infinitely long - all the signal that is fed into the cable is taken by the cable and the load.

If the impedances are not matches, part of the waves in the cable will be reflected back on the cable connections distorting the outbound waves. When these reflected waves hit the wave generator, they are again reflected and mingle with the outbound waves so that it is difficult to tell which waves are original and which are re-reflections.

The same thing happens when pulses are sent down the cable - when they encounter an impedance other than the characteristic impedance of the cable, a portion of their energy is reflected back to the sending end. If the pulses encounter an open circuit or a short circuit, all of the energy is reflected (except for losses due to attenuation - another subject). For other terminations, smaller amounts of energy will be reflected.

This reflected energy distorts the pulse, and if the impedance of the pulse generator is not the same as the characteristic impedance of the cable, the energy will be re-reflected back down the cable, appearing as extra pulses.

[MattD]

Oh and to answer the original question, you should be fine if you have your other recorder and V3 close enough so that you can use a short cable ... 1' should be fine in most situations. If you're gonna get the cable custom made, though, you might as well have it correct for the impedence mismatch as well.

[scb]

i just have a xlr > rca adapter and a standard coax cable out of the v3's aes out.  works fine to a d8 or d100

[drewloo]

I've run AES1 (consumer) > coax/SPDIF RCA out.  No need for the impedance transformer IME.  I made my own cables with Neutrik connectors and Canare cable, so not sure where to pick one up retail.

Brian, I'm about to make an AES to coax cable myself.  You wouldn't happen to remember the pin layout scheme for this?  Is it the same as this pic that power-hungry Moke put up a while back?

http://www.taperssection.com/yabbse/attachments/Unbalanced_Cable_xlrrca.JPG

[JasonSobel]

I'm about to make an AES to coax cable myself.  You wouldn't happen to remember the pin layout scheme for this?

I made myself a right-angle AES cable to run out of the v3 a while back

see this thread:
http://www.taperssection.com/yabbse/index.php?board=4;action=display;threadid=4067

I use a canare impedance transformer, so my cable is wried very simply, pin 1 to pin 1, pin 2 to pin 2, and pin 3 to pin 3.  but I'm not sure what to do if you're planning on making a XLR -> RCA with no transformer...

[barren4]

Just for the sake of argument and continued edumucation, these are stolen from the Oade forum:

#71, "RE: DIY aes/ebu > spdif cable?"
In response to In response to 1


        Hi!
 It is more a matter of voltage levels than impedance. I would use a transformer, it is a good solution and allows your connection to meet spec, not a bad idea when daisy chains are involved. I have not tried it, but tapers tell me they use a standard XLR to RCA cable (wired for audio) without a transformer and it works.
   peace...Doug
==================

 #118, "RE: DIY aes/ebu > spdif cable?"
In response to In response to 7


           Mike, another thing to think about is long term reliability of the chips. The S/PDIF voltage standard is 0.5 volts. Many use 1.0 volts, but the AES/EBU standard uses 9 volts. This might result in failure on some S/PDIF inputs as they only expect 0.5 to 1.0 volts. An output stage designed to drive a 110 ohm load will not be properly terminated into 75 ohms. The long term current sinking capacity of the output stage is another issue. I would not worry about it if I had to do it, but if I had a choice, I would use the transformer. Those pulse transformers are small and can be placed into an XLRM connector. I would use 75 ohm wire as that would allow me to add the transformer later. Probably worth the trouble...Doug