Electrical characteristics of SPDIF and AES..?

[spinjector]

I've seen discussions that indicate that the difference between SPDIF and AES3 is merely electrical.

I saw that SPDIF is unbalanced, a low voltage around 1.2v, and 75ohms, and AES is balanced, 5v, and 110ohms.

And because of this, all the usual tricks of interfacing unbalanced gear to balanced gear applies, such as transformers and/or fiddling with half a balanced pair and passive resistor pads. And in fact I seem to remember this working in the past when I played with it as a test. I seem to recall that I connected an SPDIF out from a computer to an AES input on a Sierra 64000 audio router and it worked flawlessly.

But.....is that all?

Is the data/signal really the same, or are there "certain caveats", as they say. Differences in modes/formats bits/bytes/ screams/shouts..?

I do realize that for the most part a 44100/16/2 or 48000/16/2 signal should work fine, and in fact that's about all that anyone in radio ever uses.

But are there any subformats to those signal types that might cause trouble..?

Thanks.

 

[gtomas]

There are some electrical differences and data differences, however they are not significant. If the equipment does not strictly require the parameters of the standard (especially AES/EBU) to be adhered to, usually they are compatible without any modifications.


Regards,
Goran Tomas

 

[fugazi]

Exactly,

With a simple attenuator you can simply transform AES into spdif.
I believe there is one bit/byte which could offer some problems, but most cards handle it quite well.

BR

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