optical cables?

[oldson]

hi simple question
are the more expensive toslinks any better than bog standard cheapies?
any facts to back up replies would be helpfull!
thanks

[rossman]

Here is one mans opinion

www.tnt-audio.com/accessories/toslink_comparison_e.html

[Deleted]

I've been a big user of optical signal transfer for many years and have never found an "audiophile" one that performed any better than the basic offering.

For normal analogue I like Nordost Blue Heaven (with my kit at least) and have found the VDH 102 III to work well under certain circumstances, messed about with many others but never been happy with them.

75ohm digital? Standard satellite cable with reasonble plugs will out perform pricey alternatives surprisingly. Although there are some decent ones out there too.

[Deleted]

75ohm digital? Standard satellite cable with reasonble plugs will out perform pricey alternatives surprisingly.

cjarchez
I have never been able to pick the difference between SPDIF leads of no more than 1 Metre length,even when using a rotary switch to select between a couple of different sources,BUT I think much depends on the proper implementation at both the transmit end and receive end, using decent signal transformers.
I have always found a properly impemented SPDIF superior to a normal optical setup, although optical will avoid problems due to earthing issues.For this reason I have not pursued trying various types of optical leads.

SandyK

P.S. I didn't read the review mentioned by Rossman, until after posting the section above. I hope to be trying a higher speed optical receiver in the X-DAC V3 shortly, assuming that it is easy to modify the existing to suit.I think that XTRProf may have already tried this ?

[fanboi]

Had a look at that review myself and felt that it was rather "rushed out the door" so to speak, as if he really could not be bothered but was being nagged to do it.
From what I gathered from it, I would have said his testing methodology would have been likely to conceal rather than reveal differences.
That said, it would be my preference (backed by no particular evidence one way or the other) to generally avoid optical connections except when required to eliminate earthing problems.
My suspicion is that they tend to be "the poor relations" in their most common implementations, ie, manufacturers will cut cost here first.
So, if it is correct, that the transmitter/receiver implementation is cheapo, then no cable will fix it.
Just my take FWIW

[rickcr42]

Optical cables for SPDIF audio suck on signal bandwidth even though they apparently are the cats ass for data transmission for digital communications but do i use them ?

Sometimes

If I just want to do a seriously long run and not go wireless and IF the end quality does not have to be Ultra-fi but more comparable to average Fm radio play (good enough for background music ;D ) then there are times.........

Other "personal usages" would be those goofy itty bitty combination jack direct digital outputs on portable players when I want to use the player more as a transport and which because of want to use an external dac but to be honest with Full Size digital audio sources i usually just rip the suckers out and replace them with a "proper" BNC terminated/transformer isolated coax SPDIF connection.

As for digital ground loop isolation having a pulse transformer at each end of the transmission line preserves the bandwidth while at the same time creating a "true" 75 ohm transmission line but only IF both ends are terminated with an actual 75 ohm connector (BNC) and the cable itself is 75 ohms.......

[Deleted]

As for digital ground loop isolation having a pulse transformer at each end of the transmission line preserves the bandwidth while at the same time creating a "true" 75 ohm transmission line but only IF both ends are terminated with an actual 75 ohm connector (BNC) and the cable itself is 75 ohms.......

Probably doesn't matter too much if a proper 75ohm coax lead is used, and the distance is 1 metre or less, but if you need to use a longer lead to the DAC/Receiver it would definitely pay to follow Rick's guidelines. Signal dropouts may occurr with longer leads if you don't do this.

SandyK

[rickcr42]

Probably doesn't matter too much if a proper 75ohm coax lead is used, and the distance is 1 metre or less, but if you need to use a longer lead to the DAC/Receiver it would definitely pay to follow Rick's guidelines. Signal dropouts may occurr with longer leads if you don't do this.

SandyK

correct because at that short length the cable reflections will kill you anyway

in my feeble laymans terms you can't think of data cables as you would audio transmission cables but more inline with "rf antenna theory" and as such impedances/travel distance/reflections mean everything so not only do you NEED to have a stable constant impedance along the entire path but need to keep in mind both a maximum AND a minimum cable length with the one going to losses and noise and the other cable reflections-and no matter you still need the pulse transformers if you want a proper termination at the ends...

don't care to follow constant impedance transmission and you are creating problems not easily fixed and with the cost of BNC connectors being what they are and good 75 ohm coax cable being as cheap as it is (Canare even with the additional cost of a coax stripper and a coax crimper STILL way less than many "questionable" aftermarket designer digital cables.

Ok, I need some digestion of the information. To get the music out of my computer I purchased a Chaintech AV710, which at +/-$25 was an inexpensive way to get an optical out.

If I understand the above I made a poor decission. Instead I should have purchased a soundcard w/ a coaxial 75 ohm output. So, I have a few questions:

1. Which soundcard do you all recomend? Note: All I care is to get digital out to my Oritek V4.1 Dac.
2. What is this on transformers at both end? BTW, the coaxial cable would be 6 feet long or less.

Thanks.

Don't sweat it man,the fix is a simple one ;

Option-1:Replace the optical outputs with a coax output.Both are SPDIF serial transmission streams with the only difference (other than potential quality )

Option-2:Keep the TOS,add the coax,use but one-your choice

do a google on "adding spdif output" or some such.I can probably help out with the specifics but not just now it being 4:30 AM here at the moment (blazing hot week screwing with my sleep )

the actual transformers are the most excellant ones use by Hagerman Audio (name escapes my numb brain momentarily )

as for the cable length ? 6 Ft is just about right bubba

[rickcr42]

good starting point ;D

www.epanorama.net/documents/audio/spdif.html

[rickcr42]

Why longer is better.............

www.positive-feedback.com/Issue14/spdif.htm

[leo]

Jun 10, 2008 8:37:48 GMT rickcr42 said:

good starting point ;D

www.epanorama.net/documents/audio/spdif.html

Excellent link Rick!
I'm actually going to try out this PLL synthesizing digital output www.geocities.com/koalavilla/audio_tweak.htm

[Deleted]

Rick
There is no doubt whatsoever, that a properly terminated link is the best way to go, and that short cable lengths can not achieve this. Unfortunately, most of us have very little/no control over how the manufacturers have implemented both ends, neither is it always possible to readily install proper 75 ohm BNC connectors at both ends,so that we would have very little chance of an optimum link with most reasonably priced consumer gear.

Alex

[rickcr42]

Jun 13, 2008 22:36:38 GMT @sandyk said:

Rick
There is no doubt whatsoever, that a properly terminated link is the best way to go, and that short cable lengths can not achieve this. Unfortunately, most of us have very little/no control over how the manufacturers have implemented both ends, neither is it always possible to readily install proper 75 ohm BNC connectors at both ends,so that we would have very little chance of an optimum link with most reasonably priced consumer gear.

Alex

piece of cake man.

6Ft of Canare 75 ohm RG-6 or RG-11 plus two BNC connectors,a coax stripper,a coax crimping tool.............................

DONE !

as for the internals of the electronics at each end,again a cakewalk :

Q&D : some resistors and caps
All Out : add a 75 Ohm pulse transformer

all you are doing is matching the load and blocking DC just as you would when loading an audio cable,no big assuming the internal "drive" and "receive" mechanisms are up to snuff


www.epanorama.net/documents/audio/spdif.html

a "send" example :








BTW-if the cable manufacturers/hobbyists can't get a simple coax right then i fear as well for their home video which pretty much uses an IDENTICAL cable for the 75 ohm connections so find a good video cable and you find a good spdif digital at prices i'm thinking WAY below the craziness they charge for anything once labelled "for high end audio use".

yes they will have RCA plugs and yes also no RCA plug is a 'true" 75 ohms but that still a better alternative than paying out large deniro for crap that has no shot at being 75 ohms OR good for digital anyway.

SCREW all that fancy "heavy metal" or "connectors as art" !

If you must use an RCA then the el-cheapo Canare is as good as or better than any



choose your color,Canare has 'em all ;D

[Deleted]

Rick
I appreciate what you are saying, and of course you are correct. I would do similar myself wherever possible, but it is not so easy to implement in a lot of recent consumer gear.
DIY DACs etc are of course a different matter,as the people constructing them would normally be expected to have a higher degree of expertise, and there is often a more open layout.
Better quality CD/DVD players will normally have proper 75 ohm SPDIF transformers already fitted,which makes the job much easier.

Alex.