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I'm sure that many of us have used standard XLR and RCA cables as a digital cable.I have used dedicated digital cables with varying degrees of success.Some "dedicated" cables have left me cold.Is it worth paying the additional price for these cables,or are you just as well off using the analog versions??
Please relate your experience.
Thanks in advance for your contributions.
Tom:cat
Follow Ups:
The funny thing in all this is that the SPDIF signal is ANALOGUE, not a direct digital signal!
From what I understand, what I'd call a digital signal is the typical RS232 signal from say a modem to a computer; where 0 volts represents 1 and +5 volts represents 0. Viewed on a scope it looks rather like a square wave (with varying timing of course). SPDIF is nothing like this.
SPDIF signal is an analogue carrier, with both phase and amplitude modulated; high speed modems used this kind of modulation because it is possible to encode many bits per cycle of the carrier. I used modems giving 16.8K bits per second on a line of 3300 Hz upper frequency limit.
I guess SPDIF uses this method to keep the bandwidth low and away from radio frequencies.
So ... your SPDIF cable carries an analogue signal, though of higher than audio frequencies. There is nothing specifically 'digital' about the cable, and potentially an analogue IC could work well (or not of course!).
I have tried a DIY analogue interconnect made of Belden 89259 vs a special silver SPDIF cable with excellent results (I could not tell the difference; transport was Heed, dac was Luxman DA-06, system is valve based of high resolution).
I am sure there are *no* easy answers here, but I hope the above is informative and of interest.
SPDIF is phase modulated. It is not amplitude modulated. It is a purely digital signal, transmitted at two voltage levels. SPDIF uses a variation of Manchester coding. For each bit time there will be either one or two signal transitions. This doubles the analog bandwidth on the cable, but this makes it easy to recover timing information and ensures that there will be no net DC voltage on the cable, regardless of the data being transmitted.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Thanks for pointing out my errors! And doing so nicely.
I picked up some poor info from somewhere.
I'm very familiar with synchronous data transmission where digital data is present on one conductor and its associated clock is present on a separate conductor; but SPDIF can't be exactly like that as there is only one conductor (not counting the earth screen). Though there are alternatives to SPDIF where the clock is sent on its own conductor; I think the Accuphase proprietary interface does this, and I think there are others.
I can perhaps only add that the 'analogue' performance of the SPDIF transmission may matter significantly, as I see several references to 'eye pattern' relevant to SPDIF; and 'eye pattern' is familiar to me regarding modem signals. And the 'fuzz' or blurring around the points of a modem eye pattern are ... guess what ... jitter.
Or perhaps I'm still confused! :-)
Anyway, Belden 89259 does make a *very* good SPDIF cable ...
Thought I would post a follow-up to my post.
I currently use a Clear Day RCA cable,as it has bettered a number of other cables ,feeding the Z-Systems unit (re-clock/upsample).I have a Monoprice premium XLR running to the BC-509.The sonic balance between the two is nearly ideal.
I may purchase a 1mete pair of r XLR PAD Aqueos Lumenist and compare.The "digital" are more costly and use strictly copper.I have found that the silver cables yield better high frequency reproduction,with slightly better rendition of "air"(pocketed> > more 3D) .YMMV
The PAD can be used as my phonostage link ,if it doesn't pan-out.
Tom:cat
I hate to say it,but replacing my favored combo with the analog PAD cables has converted me to an AES-EBU fan.The analog cables are performing so well that I don't feel a need to go any further.
My experience with dedicated digital cables has left me cold.
Analog rules in my book.And now on to the phono cartridge.
Tom:cat
Interesting.
I have successfully used quality RG6U 75-Ohm coaxial cable from a transport to DAC over 20-feet w/o issues and with excellent sonics. This is very similar to the stuff your Cable TV service uses. Analog audio interconnects will even work in a pinch for short distances but there's no substitute for megabuck digital audiophool reveiewed and approved cable. But everyone knows that. ;-)
Hi,
Strictly speaking techinical, we are covering a complex topic.
In an ideal world every transport would present an output Z of 75 Ohm from DC to several 100MHz.
And every DAC would present an input Z of 75 Ohm from DC to several 100MHz.
And every digital cable ever marketed would present a characteristic Z of 75 Ohm from DC to several 100MHz.
Under those ideal conditions all Cables indeed sound the same and if they do not it implicates a design flaw.
Unfortunately we live in the real world, where non of the above mkes much of a difference.
Ciao T
At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to untolerable pain. Really, what more could we need?
results will vary between brands and products within the brand. You simply have to compare to find one that suits your ear. Superb results can be obtained through using either a general RCA/XLR or purposed digital cable. Often one brand's RCA/XLR will outperform another brand's digital link. I do tend, however, to gravitate toward the purposed cable within the brand I prefer, and perhaps you will as well.
The greatest impediment to advancing an audiophile system is the audiophile.
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