SPDIF is evil

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  • ar-t
    Senior Member
    • Oct 2007
    • 217

    #46
    Well, sort of. 16' is a number that we chose to agree on. It could have just as easily been...........oh, I dunno..........12'. Or 22'. The whole point was to make something that was long enough to do the job. A few extra feet thrown in for good measure. You can go a lot further, and not degrade the signal significantly.

    Pat
    http://ar-t.co

    Comment

    • NewBuyer
      Senior Member
      • Oct 2006
      • 436

      #47
      Originally posted by ar-t
      Well, sort of. 16' is a number that we chose to agree on. It could have just as easily been...........oh, I dunno..........12'. Or 22'. The whole point was to make something that was long enough to do the job. A few extra feet thrown in for good measure. You can go a lot further, and not degrade the signal significantly.

      Pat
      Hi Pat,

      If using such a long S/PDIF coax cable for a short distance: Is it appropriate to just coil-up the extra coax cable? I've previously been advised that coiling the unused cable-length within audio setups can cause problems & should be avoided - but perhaps this doesn't apply to S/PDIF coax connections?

      Comment

      • NewBuyer
        Senior Member
        • Oct 2006
        • 436

        #48
        SPDIF is evil

        ar-t;491667 Wrote:
        > Well, sort of. 16' is a number that we chose to agree on. It could have
        > just as easily been...........oh, I dunno..........12'. Or 22'. The
        > whole point was to make something that was long enough to do the job. A
        > few extra feet thrown in for good measure. You can go a lot further, and
        > not degrade the signal significantly.
        >
        > Pat


        Hi Pat,

        If using such a long S/PDIF coax cable for a short distance: Is it
        appropriate to just coil-up the extra coax cable? I've previously been
        advised that coiling the unused cable-length within audio setups can
        cause problems & should be avoided - but perhaps this doesn't apply to
        S/PDIF coax connections?


        --
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        • arnyk
          Senior Member
          • May 2015
          • 778

          #49
          Originally posted by NewBuyer
          ar-t;491667 Wrote: [color=blue]

          If using such a long S/PDIF coax cable for a short distance: Is it
          appropriate to just coil-up the extra coax cable?
          Yes. Don't be mislead by all the BS about digital cables that is being passed around by audiophiles that lack the ability to properly test their claims.

          Comment

          • arnyk
            Senior Member
            • May 2015
            • 778

            #50
            Originally posted by pfarrell
            (starting a new thread)

            Themis wrote:
            > In any case, it would have been much better if in the digital audio
            > protocol the clock was explicitly indicated by the A/D (in the data)
            > and stored with it. This way, transport wouldn't have to add its own
            > jitter.
            >
            > Now, whatever is done, we can't go back.

            False claim. One reason why digital signalling is so valuable is that the digital signal can often be purified by means of regeneration. For example when it is read off the disc, the digital data stream that is read from optical disks is highly jittery, and often has errors. These are generally perfectly removed by the normal functioning of a standard optical disc player.

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            • Golden Earring
              Senior Member
              • Feb 2017
              • 372

              #51
              Archaeology?

              Originally posted by arnyk
              False claim. One reason why digital signalling is so valuable is that the digital signal can often be purified by means of regeneration. For example when it is read off the disc, the digital data stream that is read from optical disks is highly jittery, and often has errors. These are generally perfectly removed by the normal functioning of a standard optical disc player.
              Hi Arny!

              I'm fascinated to notice that you've suddenly popped up over here. It's actually quite spooky but disregarding that, are any of the members who previously posted on this thread still active on the forum?

              I recall that somewhere in the Good Book (which I read once in my youth for completeness) it says "there is nothing new under the sun". It seems that a lot of people were using external DACs & the word clock in on the TP back in the day, although no-one seems to have conducted any kind of rigorous testing of the ABX kind. It was interesting to find Sean Adams description of how he derived the quoted measurements for the TP. There didn't appear to be much consensus amongst the earlier posters as to which kind of lab measurements would be useful in the context of external DACs and digital connections...

              I believe that your position on this remains that it shouldn't make an audible difference because the TP's internal jitter is low enough to be inaudible & similarly that its in-built DAC is good enough to be indistinguishable from an external DAC in terms of discernible audible differences in a domestic listening environment with real ears, despite the possibility that minute measurable differences might be detected in lab testing. That's if I've understood your "reliable subjectivist" concept correctly. Please put me right if I've got any of this wrong, I'm not précising your early statements in my own words to irritate you but simply to ensure that I've fully got your drift.

              On the other thread (which has been getting a bit silly, I must shoulder my share of the blame for that!) you commented that you should perhaps write up something on the (or your, I wasn't quite sure) theory of audible perception in homo sapiens. With my deadly serious face on for once, I should be most interested to read that.

              Hope that you're having a pleasant weekend!

              Dave

              Comment

              • arnyk
                Senior Member
                • May 2015
                • 778

                #52
                Originally posted by Golden Earring
                Hi Arny!

                I'm fascinated to notice that you've suddenly popped up over here. It's actually quite spooky but disregarding that, are any of the members who previously posted on this thread still active on the forum?

                I recall that somewhere in the Good Book (which I read once in my youth for completeness) it says "there is nothing new under the sun".
                Umm yes, Ecclesiastes.

                It seems that a lot of people were using external DACs & the word clock in on the TP back in the day, although no-one seems to have conducted any kind of rigorous testing of the ABX kind. It was interesting to find Sean Adams description of how he derived the quoted measurements for the TP. There didn't appear to be much consensus amongst the earlier posters as to which kind of lab measurements would be useful in the context of external DACs and digital connections...
                If you follow the relevant scientific argument that a DAC can only have 4 kinds of technical problems, all of which are readily measurable and for whom we know quite a bit about the audible thresholds...

                I believe that your position on this remains that it shouldn't make an audible difference because the TP's internal jitter is low enough to be inaudible & similarly that its in-built DAC is good enough to be indistinguishable from an external DAC in terms of discernible audible differences in a domestic listening environment with real ears, despite the possibility that minute measurable differences might be detected in lab testing. That's if I've understood your "reliable subjectivist" concept correctly. Please put me right if I've got any of this wrong, I'm not précising your early statements in my own words to irritate you but simply to ensure that I've fully got your drift.
                Confirmed.

                The TP's internal DAC was tested pretty comprehensively by Archimago in his blog. If I ever get around to writing that article about understanding technical measurements in terms of sound quality, the executive summary can be expected to say that the TP is vast overkill. Of course people say they sound different, but as you say good listening tests confirming that are harder to find than rooster teeth.

                There are 400 or more different makes and models of audio DACs, each selling to Audiophiles on the grounds of "Better sound". Technically, there aren't that many significantly different designs. The vast majority are based on less than 20 different DAC chips with just a few using proprietary parts. Almost all of those chips are very good and can't be logically expected to audibly change the sound of music conveyed by the analog signals they output. People hoot and holler about differences in power supplies and buffers, but they are even less likely to affect sound quality.
                Last edited by arnyk; 2017-05-14, 14:51.

                Comment

                • Golden Earring
                  Senior Member
                  • Feb 2017
                  • 372

                  #53
                  Roger that!

                  Originally posted by arnyk
                  Umm yes, Ecclesiastes.



                  If you follow the relevant scientific argument that a DAC can only have 4 kinds of technical problems, all of which are readily measurable and for whom we know quite a bit about the audible thresholds...



                  Confirmed.

                  The TP's internal DAC was tested pretty comprehensively by Archimago in his blog. If I ever get around to writing that article about understanding technical measurements in terms of sound quality, the executive summary can be expected to say that the TP is vast overkill. Of course people say they sound different, but as you say good listening tests confirming that are harder to find than rooster teeth.

                  There are 400 or more different makes and models of audio DACs, each selling to Audiophiles on the grounds of "Better sound". Technically, there aren't that many significantly different designs. The vast majority are based on less than 20 different DAC chips with just a few using proprietary parts. Almost all of those chips are very good and can't be logically expected to audibly change the sound of music conveyed by the analog signals they output. People hoot and holler about differences in power supplies and buffers, but they are even less likely to affect sound quality.
                  Hi Arny,

                  Thanks for your prompt & helpful response.

                  At least I for one appear to have bothered to actually ingest your posts!

                  Relaxing into the music now (Emmylou Harris + Mark Knopfler today, All The Roadrunning + live tour album) then heading into highlights of Spanish GP. Alonso managed to put his hopelessly underpowered McLaren-Honda in 7th on the grid. He's looking like a good prospect for the Indy 500...

                  All the best,
                  Dave

                  Comment

                  • RonM
                    Senior Member
                    • Apr 2008
                    • 1491

                    #54
                    Originally posted by Golden Earring
                    Relaxing into the music now (Emmylou Harris + Mark Knopfler today, All The Roadrunning
                    That's exactly what I was doing yesterday, appreciating the technology uncritically with one of my favorite albums.
                    LMS on a dedicated server (PiCorePlayer)
                    Transporter (Ethernet) - main listen ining, Onkyo receiver, Paradigm speakers
                    Touch (WiFi) - home theater 5.1, Sony receiver, Energy speakers
                    Boom 1 (WiFi) - work-space
                    Boom 2 (WiFi) - various (deck, garage, etc.)
                    Radio (WiFi) - home office
                    Control - Squeeze Control (Android mobile), 2 Controllers (seldom used), Squeeze Remote (on Surface Pro 4)
                    Touch x 1 - spare
                    UE Radio x 1 - spare
                    Boom x 1 - spare
                    Controller x 1 - Spare

                    Comment

                    • ar-t
                      Senior Member
                      • Oct 2007
                      • 217

                      #55
                      Originally posted by seanadams
                      Just to clarify I was talking about AES/EBU _in general_. There's nothing wrong with how I did Transporter's AES/EBU output. The interface is defective by definition, and therefore not possible to execute reasonably by anyone.
                      Hope no one is upset I found this old thread and dredged it back up!

                      Too bad Sean is not around here these days. You will note what he said..................."The interface is defective by definition, and therefore not possible to execute reasonably by anyone."

                      Yeah, it is! Which is too bad. By using a balanced cable, it could have been better than plain ol' SPDIF. Especially when some jerks down in Texas try to isolate things with a transformer, which makes the shield "hot", and..................well, it isn't the best approach, but it works. But, they (AES et al) messed up. (In fact, the original version was MUCH WORSE. I had a long phone conversation with the guy who headed up the AES working group on that, and without ever seeing an implementation of it, I 'splained to him what was obviously wrong with it. I can only imagine the look of horror, on his face, as I told him what was wrong and why. Funny thing is.............................less than a year later, they came out with a new version of it! With all of my suggestions. Too bad I didn't nail him down on the output voltage, and some of the other dumb things that were in it. Just goes to show how hard it is to make things idiot proof when the idiots are so dang ingenious. And the worst piece of gear I ever saw, with AES/EBU outputs came from Philips! And cost several grand. Go figure. Guess they never thought putting DC on the output would be a problem. Worked for them, as it was designed to go with something that needed DC on the output........................oy vey.)

                      OK, where was I?

                      Ok, TOSLINK..............

                      A few years back, I measured the "jitter" of the old Toshiba TOSLINK parts, and compared them to the flavor-of-the-month Chinese brand. Since someone paid me to do this, I can not share the details. But, I can give you a rough idea.

                      All of them have a very high noise floor. That is the part that gives the "jitter number". (See other posts on why that number is useless.) The Toshiba is a bit better. The FOTM Chinese one performed better if you used the "high-speed" one. You could see the effects caused by using a crappier phototransistor in the regular speed one. It was bad. And right where you should expect a noisy transistor to have noise.

                      In all cases, all of the "jitter" contribution was caused by the noise floor. IOW, they DID NOT affect the "close-in" jitter, which is what is really important. (No, I am not going to into that. I have done so numerous times over the last decade or two, and I am not going over it again. If it annoys you, keep it to yourself. I am not interested in hearing why you think I am wrong.)

                      The fact that none of these methods (SPDIF, AES/EBU or TOSLINK) do not totally wreck the sound, even though they are highly flawed and have a ton of problems, is because it does not do anything to the signal in the most critical region. IOW, down around 1 Hz, and lower.

                      And back to the question of return loss..............

                      Yes, it does make a difference. I find it odd few ask about it. I'll just add if you get the return loss of the source, the cable and the receiver all correct (iow, below a certain level we put a lot of work into figuring out what that number is), then guess what?

                      They all sound the same. Which would put a lot of cable companies out of bidnis. Where would this industry be without something to sell the punters that will make their system sound "different"/"better"?

                      Peace. Out.
                      http://ar-t.co

                      Comment

                      • sfraser
                        Senior Member
                        • Oct 2005
                        • 300

                        #56
                        I never understood why they just can't put a decent clock and jitter buffer in the DAC . If they did , the jitter and clocking issues should disappear. A decent size jitter buffer will remove any jitter which may occur during the unidirectional transmission of the data stream from the transport device/LMS server etc. Reclocking the jitter buffer playout to the DC chip locally would also help solve the problem.
                        Home Office
                        SB2->Benchmark DAC-1-> Bryston P-25, preamp -> Carver M1.0t Amp->PMC TB2
                        Home Theater System#1
                        SB2->Anthem AVM60->Bryston 9B ST -> PSB Stratus Goldi
                        /Home Theater System #2/ LazyEye Bar
                        Pi3 w/7" screen/HiFiBerry DAC>Outlaw 976-> Bryston 3B ->Klipsch La Scala's, 2x Bryston 4B (mono) EV 18" subwoofers
                        Bedroom System
                        SB2-> Sony BoomBox
                        Rear Deck/Patio
                        Pi3 HiFiBerry DAC --> Crown XLS 1500-> PSB Mini's,
                        Kitchen
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                        Comment

                        • Julf
                          Senior Member
                          • Dec 2010
                          • 2567

                          #57
                          Originally posted by sfraser
                          I never understood why they just can't put a decent clock and jitter buffer in the DAC . If they did , the jitter and clocking issues should disappear. A decent size jitter buffer will remove any jitter which may occur during the unidirectional transmission of the data stream from the transport device/LMS server etc. Reclocking the jitter buffer playout to the DC chip locally would also help solve the problem.
                          Most modern DACs do, and use an ASRC as well.
                          "To try to judge the real from the false will always be hard. In this fast-growing art of 'high fidelity' the quackery will bear a solid gilt edge that will fool many people" - Paul W Klipsch, 1953

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