[sdiy] S/PDIF cable.

[Magnus Danielson]

From: "Batz Goodfortune" <batzman at all-electric.com>
Subject: [sdiy] S/PDIF cable.
Date: Sat, 27 Apr 2002 16:53:39 +0930

> Y-ellow all.
>          Anyone able to give me some advice on what to use for S/PDIF 
> cable. Actually more of a choice between less than ideal cables available 
> to me right now.
> 
> I can chose from the following.
> 75 ohm coax.
> 50 ohm coax
> or
> an assortment of shielded audio-type cable.
> 
> The runs have to be 5 or 6 metres in length. I guess I could do it shorter 
> as the crow flies but it won't be as neat. (Yeah Ok so 'neat' is a 
> subjective term here.) I know AES/EBU is supposed to be 110 ohm on a 
> special figure 8 but I can't just run out and buy that anywhere so it's a 
> choice of the above.

Twisted pair cables is in the range of 90-130 Ohm most of the times,
often at about 100-110 Ohm. Standard Ethernet cable (100 Ohm) for instance is
plentifull in availability. Much of the audio signal cables is really
at about 110 Ohms too.

The IEC 60958-4 (Pro-variant) specified 110 Ohm over 0.1 to 6 MHz.

It even says this:

   The interconnecting cable shall be balanced ans screened (shielded)
   with a nominal characteristic impedance of 110 Ohm at frequencies
   from 0.1 MHz to 6.0 MHz.

EBU Tech 3250 sings the same story, it actually is spot on exact in
wording, there's "rubber-stamping" standardisation working for you.

A very good document to read is the AES-2id-1996. Anyone into
understanding jitter-generation in AES/EBU or S/P-DIF should read it.

For the cable issue, the AES-3id-2001 is the reading, maybe this is a
bit over the head for some...

Also, to get a good over-view as well as insight, the EBU AES/EBU
Userguide is a very good reading.

I think I've seen some more on cables somewhere... got to look in that
filing cabinet.

Cheers,
Magnus