Thoughts on Audio: Digital Coax or Optical? (1 Viewer)

[Marty Christion]

Here's a quote which I agree with:
"RG-6 cable is excellent for running broadband RF applications like CATV and DBS Satellite LNB outputs long distances. It has excellent low-loss characteristics in the gigahertz frequency range. For the 2Mbit/sec digital signal used in S/PDIF it borders on ludicrous (sort of like driving a Peterbuilt to the corner store to buy a 6-pack, or using 4" schedule-L copper pipe to a connect a garden hose bib... you won't get any more water out of that hose). You can run 10baseT ethernet's 10Mbit/sec signals down 350 feet of TELEPHONE WIRE without a single bit loss.
*ANY* cheap coax that has 75 ohm characteristic impedance and is reasonably low-loss at video frequencies of 2-4MHz will be FINE for for S-PDIF digital audio applications. Yes, you spent $1000's on your transport and DAVs and stuff, but digital is digital, 'jitter' be damned. That cheap Sony video cable with the yellow sleeves on the chrome RCA jacks _will_work_absolutely_PERFECTLY_.
Serial digital data is clocked. If ANY jitter is introduced, its either a problem with the encoder, or the decoder. The data is buffered at the reciever end, various synchronization and subcode fields are stripped off before the actual 16 bit stereo samples are reclocked and sent to the D/A convert to make your music. It would take an EXTREME abuse of the 0V-0.5V digital signal to cause ANY audio error at all, subtle distortions of the corners of the waveforms will have NO effect. THIS IS NOT ANALOG, ITS DIGITAL. IT IS *NOT* absolutely *NOT* black magic.
Excellent technical info on S/PDIF and its actual bi-phase encoding is on http://www.hut.fi/Misc/Electronics/d...dio/spdif.html
But, then, if the gold pinstripes on those OverKill 9000XL cables make you feel better, go for it. Just remember that your beloved recordings probably ran thru several 100 feet of perfectly mundane commercial Belden audio grade cable long before it was committed to CD..."

 

[RicP]

Quote:

This is absolutely untrue with regards to a PCM audio stream. Recievers do not buffer anything and nothing is "stripped off", nor is there any reclocking done at all. Perhaps you have packeted systems like DD confused with raw PCM. Jitter is not a figment of somebody's imagination. There have been well over 50 official AES papers documenting, measuring, and discussing Jitter as it relates to PCM.