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Why does SPDIF basically suck?


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16 hours ago, One and a half said:

one needs to know the enemy in order to defeat it.

 

Without precisely measuring noise and how much can affect DAC front ends, even methods of isolation can be defeated,

 

the conquest of noise is, so far, a blunderbuss approach instead of lasers. 

 

 

Hey <2 - if you do NOT know just say so - or don't pollute in the first place

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46 minutes ago, plissken said:

 

A vast amount of sighted evaluation you mean. Validation has yet to happen. 

 

 Despite what you may wish to believe, not ALL C.A. members use sighted evaluation of the products they test !

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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19 hours ago, One and a half said:

Audio interfaces have a such a poor method of standardisation, reminds me of the Fleetwood Mac song 'Go your own Way'. Was it Sonore that listed dozens of different methods of I2S over LVDS, apart from PSAUDIO which has a small following, everyone else is going their own way. 

Part of the appeal of spdif/AESEBU/Toslink is that they are just plug n'play. Asynch  USB 2 may be slightly harder in that it might require specialized driver software in the PC.  It is the difference between a dumb, one way communications system and a smart,  two way protocol.  I simply look to my DAC manufacturer to supply that software mechanism, and I have no problems.

 

I see absolutely no inherent technical advantages in I2S vs. asynch USB, no matter the interconnection method.  It might synchronize clocking between player and DAC, but the wrong way, slaving the DAC clock to the player.  However, I2S is not designed for long interconnect runs, and clock jitter in whatever interconnect may be hard to eradicate. In the now widely available, more easily implemented asynch USB, jitter simply vanishes, except for any residual jitter, usually quite low,  internal to DAC itself as delivered via its short internal I2S circuit traces.

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10 minutes ago, sandyk said:

 

 Despite what you may wish to believe, not ALL C.A. members use sighted evaluation of the products they test !

Ok, fine.  But, which ones, and how many?  And, if your point is that the inherent superiority of spdif, etc. over asynch USB is manifest in each and generally EVERY case, how many and which different and specific implementations did they test under unsighted, bias controlled conditions?

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12 minutes ago, Fitzcaraldo215 said:

Part of the appeal of spdif/AESEBU/Toslink is that they are just plug n'play. Asynch  USB 2 may be slightly harder in that it might require specialized driver software in the PC.  It is the difference between a dumb, one way communications system and a smart,  two way protocol.  I simply look to my DAC manufacturer to supply that software mechanism, and I have no problems.

 

I see absolutely no inherent technical advantages in I2S vs. asynch USB, no matter the interconnection method.  It might synchronize clocking between player and DAC, but the wrong way, slaving the DAC clock to the player.  However, I2S is not designed for long interconnect runs, and clock jitter in whatever interconnect may be hard to eradicate. In the now widely available, more easily implemented asynch USB, jitter simply vanishes, except for any residual jitter, usually quite low,  internal to DAC itself as delivered via its short internal I2S circuit traces.

Yes, agree totally here. I2S with LVDS can work, if source to target is from the same manufacturer, using the same protocols, and the timing is taken care of. The new Auralic G2 gear may have this concept with their L-Link, but would use something different at a higher speed since their LEO reference clock operates at some MHz, yet another non standard technique.

AS Profile Equipment List        Say NO to MQA

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7 minutes ago, mansr said:

USB Audio Class devices are now supported natively by all major operating systems. Unfortunately, not all DACs expose all functionality over this standard protocol. The popular DAW products also demand (on Windows) ASIO drivers, which are another nightmare. It's a bit of a mess, but it's getting better, if slowly. That said, pure playback on recent DACs tends to be plug and play these days.

 

I2S allows either end to be the master clock. However, not all sources support slave mode. The products with external I2S over LVDS/HDMI are all over the place in this regard.

Thank you for the clarification and elicitation. 

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28 minutes ago, Fitzcaraldo215 said:

Ok, fine.  But, which ones, and how many?  And, if your point is that the inherent superiority of spdif, etc. over asynch USB is manifest in each and generally EVERY case, how many and which different and specific implementations did they test under unsighted, bias controlled conditions?

 

 If you wish to know, simply because you refuse to accept that many members still obtain improved results using additional measures, you ask them !!!

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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1 minute ago, sandyk said:

 

 If you wish to know, simply because you refuse to accept that many members still obtain improved results using additional measures, you ask them !!!

No, I quite accept that "many" have found such and such.  What I do not accept is that "many"  means anything at all under totally varied and uncontrolled conditions. 

 

Is is that all ya got besides "many"?  It seems not.

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1 hour ago, sandyk said:

 

 Despite what you may wish to believe, not ALL C.A. members use sighted evaluation of the products they test !

 

while that s a pity - it is not relevant here -- unless you have some specifics(?) so please start your own many many sighted confirmation bias welcome thread

 

I will request deletion of further off topic or trolling posts by you

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2 minutes ago, Ralf11 said:

back to TOSLINK and SPDIF - how bad are they?

Depends on the quality at both ends. Done well, it can be very good. Done poorly, it is dreadful. Feeding 192 kHz S/PDIF into a cheap Cambridge Audio receiver actually made it emit smoke. That's not done well.

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43 minutes ago, Fitzcaraldo215 said:

Is is that all ya got besides "many"?  It seems not.

 

 The sad fact remains that many people like yourself will still refuse to even accept the results of properly performed DBTs if the results don't go the way you insist they should have.

 Is it any wonder that most members who report subjective findings couldn't be bothered to even try and provide the level of proof that members like yourself so often demand ?

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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29 minutes ago, Ralf11 said:

back to TOSLINK and SPDIF - how bad are they?

 Properly implemented Coax SPDIF works very well up to 24/192 for 2 channel stereo.

Toslink, through a better than average system sounds inferior to well implemented Coax SPDIF, partly due to the extra conversion stages necessary at both ends, and bandwidth limitations (and possibly S/N too?) of many Toslink receivers.

Quite a few members do however report an improvement when a more expensive Glass Toslink cable is used.

IIRC, even wgs recommends the use of a glass Toslink cable ?

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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3 hours ago, Ralf11 said:

I will request deletion of further off topic or trolling posts by you

 

Requesting deletion of off topic posts is fine, provided that it is done for ALL members, including yourself, such as the 1st post on page 3 which was not warranted.

 

 

 

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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45 minutes ago, Superdad said:

What's the source?  TOSLINK or S/PDIF from a computer motherboard?

 

And if the Toslink or S/PDIF source is from a quality  internal Audio card, using further processing and cleaner power , not from the Motherboard itself ?

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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how reliable is the widely used "J test" that ASR and Archimago use?  All of the J test measurement data I've seen all looks like it would be a non-issue the jitter levels are so close to the noise floor and 100db below the music level at worst!  The measurements would indicate that today jitter is "solved".  

 

Then you have guys like Ted Smith (PS Audio) who can easily identify jitter.  And I can hear a difference when I use my "reclocker" right before my dac (which measured very well on its own in the J test w/o a reclocker).  This improvement I hear could be due to another issue other than jitter I suppose, but I digress....

 

I'm not sure I buy that this test is the be-all-end-all to testing the accuracy of timing.  Can someone chime in as to why the J test is inadequate?

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Well here is a J-test signal comparing optical and toslink. 

 

Computer USB source feeding Musical Fidelity V-link spdif converter.  It has coax and toslink.  I measured both into the same gear only difference being a coax or toslink connection.   Here are a couple close in 128k FFTs of that. 

 

5af7b65725a5e_Tactopti-coaxclosein40hz.thumb.png.80f2c38bfd8b0f833a6f54313f26cedb.png

 

5af7b66bc635a_Tactopti-coaxclosein200hz.thumb.png.6af4b9291a31b4b3d719b8a8d59dfc3a.png

 

Here is the Vlink with the same gear vs an Audiophilleo SPDIF converter which is BNC connected coax otherwise all the same gear.  The Audiophilleo is in light blue or cyan.  Looks much the same except a bit of a spike 75 hz each side of the central tone.  That is about 115 db down from the main signal however.  In a wider view there are a few more of those.  I would think maybe the PLL of the SPDIF input on the DAC is the main determiner of these results.  Both converters are asynch USB and probably lower intrinsic jitter than the receiving PLL is capable of managing. 

 

5af7b943be8f6_tactvlinkvsaudiophileoinblue.thumb.png.2b9c3c3dac9133fafba83889bdf804f9.png

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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  Is the top graph the toslink and the second test coax?

 

2012 Mac Mini, i5 - 2.5 GHz, 16 GB RAM. SSD,  PM/PV software, Focusrite Clarett 4Pre 4 channel interface. Daysequerra M4.0X Broadcast monitor., My_Ref Evolution rev a , Klipsch La Scala II, Blue Sky Sub 12

Clarett used as ADC for vinyl rips.

Corning Optical Thunderbolt cable used to connect computer to 4Pre. Dac fed by iFi iPower and Noise Trapper isolation transformer. 

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2 hours ago, Panelhead said:

  Is the top graph the toslink and the second test coax?

What mansr said. 

 

The top graph covers 11980 hz and 12020 hz.  

 

The second and third are showing 11,900 hz to 12,100 hz.  The top two are the same signals. 


The third one is a different pair of signals.  Toslink via V-link USB to SPDIF converter and coax via Audiophilleo converter.  Same DAC in all cases.  

 

The clock speed of the V-link relative to the Audiophilleo is different by about 60 ppm.  The V-link had the same clock rate with coax as with toslink which makes sense.  The same crystal would be generating the clock used by both connections.  

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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So the J test is done using only one tone at 0 dbfs (or close to) and observing the effects on the rest of the spectrum.  Anyone else see the shortfall here besides me?  Even if a J test ran on a sweep, it would be better, but still wouldn't really be sufficient.  Music isn't just one perfectly oscillating sine wave.  And it's reasonable to assume that when the USB chip is presented data that doesn't repeat as nicely as an encoded sine wave, that jitter could increase substantially.

 

Or maybe I'm looking at this through the lens of a lay person, and these tests are really good proxies for real music.  But I haven't heard the any counter argument yet. 

 

 

 

 

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