Coax vs. Toslink

good stuff - i'm always interested in people's set ups.

perhaps more of a function of the comcast box, unfortunately, but, like you say, who knows...

sometimes you just can't figure out why things sound the way they do.

i have comcast as well and had to switch to an optical cable on one of my tvs because of a ground loop and it took a while to even find an optical cable that came close to sounding as good as my rca cable(s) on that system.

Got a nice 2-meter optical cable from Atlona; they also make decently-priced coaxial cables - They're out of San Jose (Support local industry).

I think that going through the optical link from the cable box dodges the built-in Comcast HD/Dolby decoder in the box, which allows my preamp(Anthem 30)to apply its own Dolby PL-IIx. TV sound is acceptable (Not my area of interest - Annoying ads are the same in any decoding). In any event, the two classical stations on Comcast are quite tolerable.

Cheers,
Jon

Cable boxes have a different earth ground than the AC outlets. This is why I use a Jensen isolation transformer on the RF cable before it enters the cable box. Once I did this, the coax sounded better, but its a really good coax.

Steve N.
Empirical Audio

The reason why the optical output sounds better than the coax on your cable box is most likely that it isn't an electrical connection. Without an electrical connection, it can't transmit it's own electronic noise to the rest of the system. Ground differences between them are also eliminated.

Too many people say coax always sounds better than optical. They probably haven't tried a good glass optical cable and/or the source they were using didn't transmit much electrical grunge.

A good glass cable doesn't have to cost much. I use a Sonicwave glass optical cable from Amazon that I paid $25 for. Sounds excellent.

Audioengr wrote:
Cable boxes have a different earth ground than the AC outlets. This is why I use a Jensen isolation transformer on the RF cable before it enters the cable box.

But it doesn't have to be a different earth. It took 5-6 visits from cable techs before I could convince one to actually MOVE the cable ground next to the main house ground. It took him less than 5 minutes and it is a permanent cure, not a band-aid.

Kal

+1 with Kbarkamian...

I commented on another identical thread like this and concluded that my optical connection certainly sounded better. There seemed to be something extra mixed into the sound when I hooked up the coax. So for cd/dvd/blu-ray playback I run optical into the dac. I'd run optical from the sonos but considering the bit stream is only at 192k/b and I only have one optical connection on my dac I just use the coax on that. In a way I think the coax works better for the sonos because it mushes the incoming signal just enough to make it sound better. :)

This topic resurfaces every 18 onths or so - below is link to earlier thread.

http://forum.audiogon.com/cgi-bin/fr.pl?fcabl&1019742769&openusid&zzUpgrade1394&4&5#Upgrade1394

IMHO, I have NEVER found coax to sound better than a decent toslink - the toslink has better body, lower noise floor and just overall clean musical sound. In some systems, poorly executed optical outs (especially high-end gear which biases towards selling astronomically priced coax cables) may give a false impression of inferior sound, but all things being the same (i.e. execution and cost of coax and toslink outs), the optical is inherently superior. Please, do not even mention bandwidth...

Well, the bandwidth is the problem. Toslink has very low bandwidth (tens of MHz) while coax has high bandwidth (hundreds of MHz). Because of limited slew rate in Toslink system (receiver and transmitter) noise converts to jitter (because noise affects threshold). Many measurements showed Toslink having 2x worse jitter than coax. On the other hand non-expensive transports have slew rates in order of 25ns making it similar to Toslink. Fancy transport can swing in few ns but this requires expensive well impedance matched digital cables to avoid reflections on impedance boundaries. Whole thing is system dependent making it difficult to make any definitive statements. Often Toslink is a blessing since it breaks ground loops.