optical cables all created equal?

[nick_charles]

Nobody, anywhere with any combination of any format of optical cables of normal length (non faulty) at any price levels or construction or any material has ever shown any verifiable measurable differences in the integrity or interpretation of an optical data stream passed from transmitter to receiver, the end....afaik - if someone can point to some ***empirical*** evidence to challenge this I will be more than happy to read it, and I heard a difference does not count...

 

[Dr. Strangelove]

welcome to www.jitter.de

A good read for those interested. They state that they used a long Toslink (10 meters) to make the measurable jitter more apparent for the scope.

 

[nick_charles]

Quote:

Originally Posted by Dr. Strangelove /img/forum/go_quote.gif welcome to www.jitter.de A good read for those interested. They state that they used a long Toslink (10 meters) to make the measurable jitter more apparent for the scope.

10 meters is bang on the limit for toslink optical cables without using repeaters and these chaps sell a jitter attenuator so are maybe not the most unbiased source ?

 

[Andrew_WOT]

Quote:

Originally Posted by Dr. Strangelove /img/forum/go_quote.gif welcome to www.jitter.de A good read for those interested. They state that they used a long Toslink (10 meters) to make the measurable jitter more apparent for the scope.

Excellent article. Thanks for posting that.

 

[Maxvla]

But really who runs a 25 foot optical cable?

 

[krmathis]

Quote:

Originally Posted by Dr. Strangelove /img/forum/go_quote.gif welcome to www.jitter.de A good read for those interested. They state that they used a long Toslink (10 meters) to make the measurable jitter more apparent for the scope.

Thanks!
Looks like a *must read* ...

 

[qusp]

Quote:

Originally Posted by Devolve /img/forum/go_quote.gif Are these "slightly different times" even detectable at the speed of light?

lol whether something is traveling at the speed of light or a snails pace is irrelevant; if a reflection causes a piece of information to arrive later than it should; then the signal will be decoded in a way that is inaccurate.

 

[ashmedai]

Quote:

Originally Posted by Dr. Strangelove /img/forum/go_quote.gif welcome to www.jitter.de A good read for those interested. They state that they used a long Toslink (10 meters) to make the measurable jitter more apparent for the scope.

*cough*snake oil*

 

[Chri5peed]

All this talk of jitter, is it acftually a noticable pop or jump?

As my DAC can use all 3 digital signals, I've extensively used all 3 and have always gone back to Optical, never given me cause for concern.

 

[moogoob]

Quote:

Originally Posted by Devolve /img/forum/go_quote.gif $2 cables deserve some sort of award then for slowing down the speed of light.

This may belong in sound science, but technically ANY transparent material (other than a vacuum, which is the absence of material) slows the speed of light.

That's what refraction is indicative of.

/Okay, you can all get back to your regularly scheduled thread

 

[tubaman]

This is all you need.[/QUOTE]

I once had someone told me that when she saw my $600 truck.

 

[Dr. Strangelove]

Quote:

Originally Posted by ashmedai /img/forum/go_quote.gif *cough*snake oil*

How is it snake oil? They cite papers written by experts, show scope measurements.

 

[ashmedai]

Quote:

Originally Posted by Dr. Strangelove /img/forum/go_quote.gif How is it snake oil? They cite papers written by experts, show scope measurements.

For starters, since you like that one: Scope measurements? Showing minor fuzzyness? On a DIGITAL signal?

That, assuming they didn't rig it, which would be almost trivial to do.

(Yes, I'm being deliberately vague, because I don't want to get into a detailed technical discussion. And I definitely want to avoid a protracted argument about cables on head-fi, which is about as fun as fighting a land war in Asia in the dead of winter. But it should be clear enough what I'm thinking is wrong if you've used an oscilloscope much & had experience with digital signals. But then again if you did wouldn't you have been all "hey, wait a minute..." too? Hmm...)

 

[nick_charles]

Quote:

Originally Posted by Dr. Strangelove /img/forum/go_quote.gif How is it snake oil? They cite papers written by experts, show scope measurements.

Actually they are being a bit misleading and I shall explain why.

1. They use 3ns as an exemplar for jitter, this is a lot of jitter but still below the threshold of human perception (Benjamin and Gannon, 1998)

2. They cite Julian Dunn. Dunn never measured the audibility of jitter ever, he modelled it but never ever performed any jitter listening tests and even revisited his views on audibility after B and G..

3. The BB paper states that all digital is PCM, where have they been since 1998, no mention of DSD ???

4. 3ns is a lot of jitter, and way above what commercial audio device actually sport in jitter terms, read a few stereophile measurements of digital audio devices , you will not find any **CD** players with 3ns jitter , a music server and one DVD player but no , even cheap end, CD player manifests 3ns jitter.

5. 3ns is inaudible in "proper" listening tests

6. The Philips CD723 had to be **bodged** to give it an optical feed, it does not have one normally, hmmmm no possibility that they didnt rig that test ?. Why did thye not buy a CD player with an optical out ?

7. Sighted listening tests sigh

 

[ashmedai]

Nick also has good objections, and is more explicit about them than I.