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-   -   What difference does the quality of a digital interconnect make? (http://www.diyaudio.com/forums/digital-source/240184-what-difference-does-quality-digital-interconnect-make.html)

stijn001 2nd August 2013 07:13 AM

What difference does the quality of a digital interconnect make?
 
First post so please excuse my ignorance....:o

I’v been pondering over this question for a while. I have a telecoms background and know a few things about digital cabling in general, although I’ve no knowledge of error correction/bit error rates, line speed negotiation, clocking etc.. with for example USB1.1/2/3 or SPdif/toslink etc.type interfaces.

If the digital interface specification is exceeding the required line rate (in relation to the sample rate of the material) and the interlink is conform specification then what difference does the “perceived” quality of the cable make? Since all we are trying to achieve is to recover sufficient bits at the other end.

The only thing I can think of is that these interfaces are prone to produce a lot of bit errors if no quality components are used. Is there a way (possibly some software), to measure this with.

ashok 2nd August 2013 10:34 AM

A poor interconnect could introduce jitter due to impedance mismatch. Just use 75 ohm coaxial cable and 75 ohm plugs. Neutrik has them. Best is to change all sockets and plugs to BNC's. Also from Neutrik.

AndrewT 2nd August 2013 11:11 AM

Digital signaling is effective HF signaling.

The cable and it's connectors must be suitable for HF.
That means accurate terminations at both ends and accurate maintenance of the cable impedance through the connectors and of and onto the boards.

If it is specified for 75ohm, then everything must be 75ohms +- some tolerance.
RCAs don't work !!!!

DF96 2nd August 2013 12:25 PM

A carefully-wired RCA may be little worse than a poorly-wired BNC (e.g. long tails to a PCB). A short piece of wrong impedance line will not cause huge reflections - we are only talking VHF at max.

stijn001 3rd August 2013 04:49 PM

I was suggesting the cable would be within specification. How can it be justified spending 10USD versus say 200USD for a digital interlink? As this is still part of the digital signal path there shouldn't be any degradation.., I don't get it. Or is it just the "bling" factor?

SY 3rd August 2013 05:12 PM

Quote:

Originally Posted by stijn001 (Post 3583702)
Or is it just the "bling" factor?

Bling-o, errrr, bingo!

Extreme_Boky 3rd August 2013 09:48 PM

Quote:

Originally Posted by stijn001 (Post 3583702)
I was suggesting the cable would be within specification. How can it be justified spending 10USD versus say 200USD for a digital interlink? As this is still part of the digital signal path there shouldn't be any degradation.., I don't get it. Or is it just the "bling" factor?

It can be if the cable is assembled from, for example, gold plated solid core silver hot conductor while the insulation material/dimensions and shield construction still provide 75 ohms impedance. Termination is crucial; fine tuning is expensive. But the end results can be quite outstanding. Yes, I know it is only a stream of 0s and 1s

Boky

marce 5th August 2013 12:09 PM

If the cable is correctly engineered, then no difference. It is basic digital signal transmission of which there is plenty of information out there. The main thing as already pointed out is impedance matching, get that correct and avoid impedance mismatches then you will have no problem
Exotic materials, gold or silver connectors are not gonna make any difference, but this is audio so like everything else there are myths regarding digital cables and digital signal transmission.
The basic method of looking at an interface is to use eye diagrams, this gives you the overall picture of how well the cabling and interface is performing.

stijn001 5th August 2013 01:11 PM

Hi Marce, just as I thought. I’m familiar with the use of eye pattern in relation to testing, being able to recover bits. I’m also now pretty convinced the whole “high-end” digital cabling argument is a Hoax.

Extreme_Boky 5th August 2013 01:35 PM

Sure about that? What about the speed the signal travels down the wire? Can you check that as well by observing the eye-pattern in a single instance in time? Saying that this speed is not important is the same as implying that jitter doesn't make any difference with regard to digital sound. And how about the oxidation and the resulting loss due to the increased resistance and the skin effect at high S/PDIF frequencies? Do you know that even silver - oxide is a better conductor compared to copper? All this aside -> have you ever heard what gold-plated pure silver, annealed cable does to the (even digital S/PDIF) sound?

It is possible to extrude the {RCA pins at both ends WITH the "hot" solid core wire between them RCA pins}, from a single piece of the thick silver wire. No soldering required.


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