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Copper vs Optical Fibre

Can anyone answer me (especially the equipment manufacturers) why copper connected components can have signal clarity and capacity to 32bit/768kHz, DSD 128, 256 etc, while optical fibre connections (toslink and the like) are restricted to 24bit/96, DSD over DOP, PCM if you are lucky to them up-sampled. In Australia, the National Internet being rolled out has very high up/download speeds on fibre is you can get it, and lousy speeds on copper. Why is optic fibre not used more extensively (between components and speakers if possible) as it does not suffer the maladies of copper connections?
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7 responses Add your response
erik_squires
16,058 posts
 
History really. In terms of analog transmission of audio, copper is good enough, and plenty easy to modulate. Fiber is relegated to digital only. 

So there's that. Next, if we are talking digital, while the USB standard evolved, the S/PDIF spec got stuck in the mud. Unlike S/PDIF, USB has asynchronous data transmission, allowing the DAC to drive the train, and not the source. Most modern DAC's include galvanic isolation, so the noise stays on one side of the connector. 

Best,

E
mattmiller's avatar
mattmiller
1,497 posts
 
It offers the WORST connection and the MOST Jitter...thats why. And as you pointed out its limited in resolution and bit rate. Utility companies love them because they are light weight and 100% isolated from electrical interference.

Matt M
amg56's avatar
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amg56 OP
887 posts
 
Hmmm....  so far so good. I can accept those explanations. If there is a (mild) expansion in self powered speakers, as per the new Dynaudio Focus 60XD, I would have thought there would have been a higher resolution on the digital side, but the copper cables to each produce a higher reproduction, according to the report. I honestly thought that optic cable would have the purist (albeit digital) transmission. It would certainly be cheaper than some of the big brand copper cables.
erik_squires
16,058 posts
 
@amg56 You might want to check out Meridian and see what they are offering lately. They have always been at the bleeding edge of digital, powered speakers. 
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amg56 OP
887 posts
 
@erik_squires I am not in the market for a set of digital powered speakers at this time. I put out the question because I didn't understand the "inner machinations of HiFi" such as jitter and so on. Slowly, as I read these posts, I am learning. It would be a game changer if the difficulties could be fixed.
erik_squires
16,058 posts
 
Well, I have read some measurements suggesting coaxial has better jitter reduction, but not sure how much, or that it is universal. 

This may be less important as DAC's in the last 5-8 years have much better jitter reduction overall than previous generation. 


willemj
1,036 posts
 
Archimago has measured the various interfaces, and usb turns out to be best, followed by coaxial, followed by optical. The differences only seem relevant at higher resolutions. See here for some of those measurements (but dig deeper and you wil find more): http://archimago.blogspot.nl/2017/08/measurements-smsl-a6-as-dac-part-ii.html
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