Using RCA analog cable as RCA digital?

[nightyy]

Hm, it works, but is it safe and sane?

I bought used Oehlbach NF 214 cables (http://www.oehlbach.com/products/home_hifi.php?lang=de&cat=57&cat_parent=6), and have some excess in RCA stereo connections now. As I only had cheap RCA digital coax cables I thought why not use the NF 214 as digital cable?
I opened the plug and the NF 214 is definitely a coax cable, so I tried using it betwenn a SBT and a Beresford Bushmaster: and it works and sounds just fine.

Why are those two types of cables sold in two different categories?

[camtwister]

Is it not because a digital coax cable and its termination is specified at 75 ohm impedance for ideal loading and transmission? The tolerances of analogue cables are wider, in this respect.

[Alex_UK]

Exactly - it is the impedance that is important - but you won't blow anything up using an analogue interconnect.

[nightyy]

I just looked up the NF 214 specs, it says 7 Ohm/m, so taking into account I use 0.7 meters that's around 5Ohm! The plugs are soldered to the cable.
Plugs per se do not have a (relevant) resistance, so I would currently be running that connection with 5 instead of 75 Ohm? Wouldn' that imply with U=R*I, that with constant voltage the current flow goes up by the factor 15? It sounds unhealthy for sure.

So would a SPDIF cable by design need to have a resistor in one of the plugs with (75-cablelength*Ohm/cablelength) Ohms?

One more question: satellite coax cables are specd with 75Ohm, does that mean 75Ohms/meter? Wouldn't that add up considerably over say 40 meters?

Or does the specification 75Ohm mean that the endpoins/devices do have resistances of 75Ohms each and the cable adds up to that?

[hifi_dave]

Perfectly safe and if it sounds good, don't worry about the specs.

[DSJR]

Who says 75 Ohms is important? Maybe today, but in the past, many transports and DAC's, including an old Meridian, were anything but :)

Most coax cables will transmit a digital signal ok and modern "receivers" shouldn't make mincemeat of that fact. I compared a length of surplus satellite-grade coax (a Belden of some description) to one of Dave W's w@nky sooper-dooper top secret concoctions and the bloomin' difference wasn't that marked, not really :lol:

[synsei]

I've been using a spare Belkin PureAV Silver IC for digital duties between the PC and the Caiman for months without issue, in fact it sounds pretty good ;)

[camtwister]

Who says 75 Ohms is important?


If you'll pardon the facetious response (:)),
then the Audio Engineering Society, the European Broadcasting Union, the Sony Corporation and Philips Electronics do.

http://www.aes.org/publications/standards/

That does not imply that I disagree with post #5.

[NRG]

Unless you are using bnc connectors it's a crap shoot. Fit these to your kit and cables with correct 75ohm impedance and suddenly all cable differences magically disappear ;)



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[sq225917]

Impedance isn't the same as resistance, just sticking and ohmeter on it doesn't tell you what the impedance is, it'll give you an idea....

http://www.physlink.com/education/askexperts/ae517.cfm

[DSJR]

I think it was Paul Miller in 'Choice many years ago who tested the output impedance of transprts and the input impedances of their matching DAC's. The Meridian 600 series was all over the shop (I can't remember if the two actually matched each other though) although I think the Linn Karik/Numerik in their first incarnation were pretty good, but it's a very long time since I read the group test reviews..

The general incompetance of much domestic kit really is evidenced by the fact that cables really do seem to make as much a difference as they do. As said above, get the impedance matching right, and many of these audible differences disappear.