Why does SPDIF basically suck?

[jabbr]

2 hours ago, Fitzcaraldo215 said:

What could possibly be better than total control of the totally buffered d-a process by the DAC master clock?  Oh, wait.  Spdif/Toslink/AESEBU do not do that.  Asych USB does.  Hmmm.

 

No doubt one could treat SPDIF as an async clock, and do a proper clock domain crossing rather than reconstruct the clock at the receiver. No doubt one could reimplement the Toslink transceivers using high quality, low jitter optics. No doubt a new version could overcome the low bitrate limits. The real world, however, has moved on. More modern synchronous alternatives such as I2S via LVDS over HDMI haven't achieved market penetration and require specialized PCIe cards ... and still don't do DSD.

 

Realistically we have USB and Ethernet and Thunderbolt moving forward 

[jabbr]

10 minutes ago, Ralf11 said:

 

which is best?

 

and how bad is the optical link in the Apple TV3?

 

 

The market will sort that out and no doubt there is a role for all three. 

 

USB: is here to stay, particularly if we consider Lightning as a variant of USB -- In my view not the best technically going forward but will likely hold the mass market DAC space.

 

Wireless and bluetooth will hold a space as well (should have placed these on the above list)

 

Ethernet: my favorite for long term "best"

 

Thunderbolt: hmm ... gaining traction in the "pro" space, I see this taking over the prior "Firewire" segment? Maybe, we will see. Don't have enough personal experience to compare with Ethernet.

 

I still put my $$$ on a singlemode fiber SFP+ module for killing the price/quality comparison. Hands down at this point.

 

optical link from Apple TV3 ain't no single mode

 

 

 

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1 minute ago, esldude said:

I have a Thunderbolt interface that also does USB.  I suppose I must consider the Thunderbolt to be superior as the required cable costs the most. 

Thunderbolt is basically PCIe on a wire — so if you have a PCIe card, easy to remote. 

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7 minutes ago, esldude said:

Yes I was just thinking the electron spin is reversed below the equator or something like that. 

Maybe that’s why the Internet works differently there? Ethernet cables have the wrong chirality — but fiber? ?

 

Hmmm ... perhaps we could do balanced streaming where the (-) path goes in the Southern Hemisphere ... and do we need to listen in Ecuador?

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28 minutes ago, mansr said:

No, you can't. You can do something more elaborate than the standard PLL and achieve much lower jitter, but you always must somehow avoid drift between your local clock and the incoming signal. USB does this by providing a feedback channel whereby the receiver can instruct the sender to slow down or speed up as needed to keep the fifo at a suitable fill level. S/PDIF is unidirectional, so nothing like this is possible there.

Of course it’s possible — every reasonable FIFO codes for the possibility of buffer over or under runs. Big enough buffer and should be statistically rare. 

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2 hours ago, Superdad said:

 

Remember, DACs which have digital isolators (what you refer to as galvanic isolation) ALWAYS have them on the I2S lines AFTER the USB input PHY/processor. (So far the ONLY exception to that is the new Auralic Vega G2, which uses the same Silanna isolator chip as our ISO REGEN, right at the input.)

 

 

 

Please, @PeterSt isolates the Phasure NOS1a/G3 at the USB input 

 

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21 hours ago, Ralf11 said:

how does that noise get transmitted?  are you claiming it goes thru the optical cable?

It does! Toslink uses very cheap transceivers GIGO — not the photon’s fault