[linux-audio-user] External DAC for mastering use?
anahata at treewind.co.uk
Tue Mar 23 06:39:00 EST 2004
On Tue, Mar 23, 2004 at 10:27:02AM +0000, Daniel James wrote:
> Currently its about 18 miles away, but I might convert a building in
> the garden for recording purposes. Do you know what the limitations
> on the length of S/PDIF cables are?
S/PDIF (IEC-958) uses 75 ohm coaxial cable and RCA connectors. 75 ohm
coaxial cable is inexpensive, because it is the same cable as used in
video transmission (you can buy a video cable with RCA connectors to
connect you S/PDIF equipments together). Coaxial S/PDIF connections work
typically at least to 10-15 meter distances with good 75 ohm coaxial
Because high light signal attenuation in the Toslink fiberoptic cable,
the transmission distance available using this technique is less than 10
meters (with some equipments only few meters).
I wouldn't normally do your Googling for you, but I was quite interested
in the answer myself :-)
That link also mentions the AES/EBU standard, which uses the same
signal timing but higher levels and will therefore travel greater
distances: "AES/EBU signal transmission work for few tens of meters with a
good cable." - The cable has to have 110 ohm characteristic impedance.
I'm also interested in the possibility of feeding S/PDIF over structured
cabling using CAT 5 cable. Has any one tried this? I wonder how far it
would go with suitable impedance conversion. 50/75 ohm transformers
would also give electrical isolation.
anahata at treewind.co.uk Tel: 01638 720444
http://www.treewind.co.uk Mob: 07976 263827
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