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In Reply to: RE: Digital cables posted by Mike C on June 15, 2015 at 16:12:38
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
Follow Ups:
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.
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