Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
jeffmeh;238373 Wrote: Newtonian physics is also inferior to Einsteinian physics. While that is an important distinction when trying to precisely calculate the paths of celestial bodies, it is not a consideration when playing billiards. Finally, something that an engineer of the mechanical persuasion can understand. This is the quote of the thread, IMO. Nice work everyone. -- mattbrown521 mattbrown521's Profile: http://forums.slimdevices.com/member.php?userid=13220 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Despite coming from an engineering background and being firmly of the opinion that it couldn't possibly matter, my opinion on the audible impact of clock jitter was changed forever when I sold my early, expensive DVD player and replaced it with a cheap recorder. I figured that 'bits is bits', and that as long as both managed to deliver a correct SPDIF output, both would sound identical through the same external DAC. (The one in my Yamaha DSP-A1, in this case). I was wrong. It took me a couple of weeks to fully realise it, but my music sounded flat and two-dimensional. The soundstage had become fuzzy and indistinct. On a couple of occasions it was so annoying that I had to just switch it off. Yet, in a quick back-to-back test, I very much doubt I'd be able to tell the difference. I ended up having to buy a new player, and sure enough, that cleared up the problem immediately. On the technical side: typical accuracy for a quartz crystal is around +/- 50 parts per million, with higher precision available at exponentially increasing cost. So, if the source and DAC were mismatched by that amount, the DAC would have to interpolate or drop 2.2 samples per second. Audible? Probably not. Good for marketing? Unlikely. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;238637 Wrote: On the technical side: typical accuracy for a quartz crystal is around +/- 50 parts per million, with higher precision available at exponentially increasing cost. So, if the source and DAC were mismatched by that amount, the DAC would have to interpolate or drop 2.2 samples per second. Audible? Probably not. Good for marketing? Unlikely. 2.2 samples/sec. X 60 sec./ min. X 80 min. / CD = 10,760 samples dropped or interpolated over the length of a CD. 10,760 samples / 44,100 samples / sec = 0.24 sec starting delay to half fill a FIFO buffer 0.53 sec. for 96,000 samples sec. I could live with that. Bill -- Listener Listener's Profile: http://forums.slimdevices.com/member.php?userid=2508 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;238566 Wrote: I think you're over-analysing the behaviour of the TOSLINK connection, and making comparisons that don't really apply. Of course if you're considering long-distance high speed communications, then pulse spreading due to optical line width and multiple propagation paths along the fibre are significant. But over a few feet, running at 5.6 MHz? (As an aside - try looking up a data sheet for the type of high speed comparator used as a line receiver for coax. I bet you'll find a skew, which translates into data-dependent jitter, which is orders of magnitude greater than any spreading due to optical effects in the cable). What I do find surprising is that anybody designs a DAC that uses the SPDIF input as a timing reference rather that merely a source of bits. I've spent some of my spare time this year designing a DAC - based around the AK4396 as it happens - which makes no attempt to directly recover a clock from the SPDIF input. Incoming edges are used merely to identify where bits start and finish so they can be sampled correctly, nothing more. So, it's an inherent property of the design that input jitter makes no difference at all. Doing this is not expensive, and I don't regard the use of a crystal and an FPGA as fancy. I do, however, regard the topology as correct - and, fortunately for those of us with a working design with commercial potential, unusual. One day, all DACs will be made this way. Ah.but you are assuming that a few feet and 5-6 MHz aren't all that hard to do. Actually, the laser diodes used in the glass fibre setups do not like a few feet of fibre. Light bouncing back from the RX end does all sorts of odd things to it, at those lengths. It is not a problem of spreading, but that the spectral lines move around way too much. I call them fancy, because most D/A boxes do not do that. They take the usual Crystal RX chiphook it up as shown in the data sheet (which was written by people as wrong as the engineers who designed it), and figure it will work. Yes, it obviously works. But how well is another matter. Since you seem to have some technical background, here is something to try: Put a audio listening device (I'll let you decide the best way) to PLL loop filter point on the RX chip. Listen to it. Then play some music and then listen to it. You may be surprised. Or sickened, possibly both. Then report to us, and let the naysayers tell you that jitter is a lot of codswallop. -- ar-t http://www.analogresearch-technology.net ar-t's Profile: http://forums.slimdevices.com/member.php?userid=13619 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Phil Leigh;238540 Wrote: Welcome to the forum - and thanks for the gratuituous comment. I was under the impression that being informed was the converse of being uninformed and thus represents a binary state. Therefore, being grossly uninformed makes no sense, since one cannot be less informed than uninformed. Since I didn't mention TOSLINK in my comment, I'm not sure what you are taking exception to. ADAT LightPipe (for example) is a variation on Toslink that has been in pro-use for a long time and some great recordings have been made using it - so clearly it can't be all that bad, can it? Also, no matter what your oscilloscope says, few people can reliably distinguish optical vs. SPDIF in various systems with their actual ears...this may well be because the DACS they are using effectively deal with the jitter arising from both the Toslink and SPDIF interfaces. My point was simply that IN PRACTICE there is little if any to choose between them. Theory well may say otherwise...but then theory has a poor track record compared to practice IMHO. You are the one who said it was a myth, not me. You can parse my words, but if you believe that it is a myth, then you are wrong. Misinformed, uniformed, or just plain ol' wrong: take your pick. TOSLINK and glass fibre both have problems. But for different reasons. It is possible to make a high-qulality fibre link, but few know how to do it. (They could start by reading the app notes more closely for a start.) Just because some people can not distinguish between the two is not the same as concluding it is a myth. Which you seem to have done. As to the great recordings that you refer to: how many were done that had an external clock fed to them? Anyway, there are sonic differences that can be heard. No, it does not take the most expensive system known to mankind to hear it. We have demonstrated in many times when we were in the business of selling that type of equipment. Somehow, it never hurt our sales. BTWthanks for the welcome! Pat -- ar-t http://www.analogresearch-technology.net ar-t's Profile: http://forums.slimdevices.com/member.php?userid=13619 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Many (all?) studios would now use a house clock to lock everything. However, this wasn't always the case. The myth I was referring to was the assertion that optical always sounds worse than coax. IMHO that is simply not true. I have found either no discernible difference or a very slight difference/preference either way depending on the components of the system. YMMV. -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... ...SB3+TACT+Altmann+MF DACXV3/Linn tri-amped Aktiv 5.1 system and some very expensive cables ;o) Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
I'd be interested to know if you can quantify the random and data-dependent jitter that's inherent in a TOSLINK connection. The receiver I'm using, for example, specifies a pulse width distortion of up to +/- 20ns, and a random jitter that's typically 1ns but with a max of another 20ns. At 44.1kHz, the line rate on the SPDIF interface is about 5.6 MHz - the pulse width is 177ns. So, whilst the receiver isn't so bad it's going to hamper reliable data recovery (provided the transmitted signal isn't total rubbish, of course), recovering a low-jitter clock from it could be a real challenge. If you can put a figure on how much of that jitter or skew is inherent, and how much of it is down to the cheapness of the receiver, I'd love to know. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;238637 Wrote: On the technical side: typical accuracy for a quartz crystal is around +/- 50 parts per million, with higher precision available at exponentially increasing cost. So, if the source and DAC were mismatched by that amount, the DAC would have to interpolate or drop 2.2 samples per second. Audible? Probably not. Good for marketing? Unlikely. Somone correct me if I am wrong, but that would only be the case if there is absolutely no jitter in the clock mismatch, and also only if we are talking about a configuration with a buffer design that is not very smart, where the mismatch *has* to lead to sample discards. It's relatively simple to design things as if to avoid discards every time there's a mismatch in an free running asynchronous configuration (and in audio systems we are talking plesiochronous rather than asynchronous). -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
opaqueice;238369 Wrote: Going into a Benchmark DAC1 I can't hear any change; same with a NOS DAC I experimented with. Yeah, but you can't hear the difference between a SB3 and a Transporter! -- Patrick Dixon www.at-tunes.co.uk Patrick Dixon's Profile: http://forums.slimdevices.com/member.php?userid=90 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Patrick Dixon wrote: opaqueice;238369 Wrote: Going into a Benchmark DAC1 I can't hear any change; same with a NOS DAC I experimented with. Yeah, but you can't hear the difference between a SB3 and a Transporter! Heh, I had exactly the same thought! R. ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Patrick Dixon;238470 Wrote: Yeah, but you can't hear the difference between a SB3 and a Transporter! Robin Bowes;238489 Wrote: Heh, I had exactly the same thought! Can you, blind? -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
ar-t;238344 Wrote: It is inferior, and it is not a myth. You are grossly uninformed. Galvanic isolation can be achieved by using transformers, althoough doing so requires some skill on the part of the designer. Of all the optical methods, TOSLINK is the worst. Single-mode fibre could be used effectively, but alas, the way it is commonly implemented is all wrong. (In case anyone actually cares, I helped to engineer the world's first single-mode long-haul fibre system. I may just have an idea what I am talking about. Not that the ignorant will care; they rarely are open-mended enough.) Pat Welcome to the forum - and thanks for the gratuituous comment. I was under that being informed was the converse of being uninformed and thus represents a binary state. Therefore, being grossly uninformed makes no sense, since one cannot be less informed than uninformed. Since I didn't mention TOSLINK in my comment, I'm not sure what you are taking exception to. ADAT LightPipe (for example) is a variation on Toslink that has been in pro-use for a long time and some great recordings have been made using it - so clearly it can't be all that bad, can it? Also, no matter what your oscilloscope says, few people can reliably distinguish optical vs. SPDIF in various systems with their actual ears...this may well be because the DACS they are using effectively deal with the jitter arising from both the Toslink and SPDIF interfaces. My point was simply that IN PRACTICE there is little if any to choose between them. Theory well may say otherwise...but then theory has a poor track record compared to practice IMHO. -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... ...SB3+TACT+Altmann+MF DACXV3/Linn tri-amped Aktiv 5.1 system and some very expensive cables ;o) Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
ar-t;238344 Wrote: It is inferior, and it is not a myth. You are grossly uninformed. Galvanic isolation can be achieved by using transformers, althoough doing so requires some skill on the part of the designer. Of all the optical methods, TOSLINK is the worst. Single-mode fibre could be used effectively, but alas, the way it is commonly implemented is all wrong. (In case anyone actually cares, I helped to engineer the world's first single-mode long-haul fibre system. I may just have an idea what I am talking about. Not that the ignorant will care; they rarely are open-mended enough.) Pat I think you're over-analysing the behaviour of the TOSLINK connection, and making comparisons that don't really apply. Of course if you're considering long-distance high speed communications, then pulse spreading due to optical line width and multiple propagation paths along the fibre are significant. But over a few feet, running at 5.6 MHz? (As an aside - try looking up a data sheet for the type of high speed comparator used as a line receiver for coax. I bet you'll find a skew, which translates into data-dependent jitter, which is orders of magnitude greater than any spreading due to optical effects in the cable). What I do find surprising is that anybody designs a DAC that uses the SPDIF input as a timing reference rather that merely a source of bits. I've spent some of my spare time this year designing a DAC - based around the AK4396 as it happens - which makes no attempt to directly recover a clock from the SPDIF input. Incoming edges are used merely to identify where bits start and finish so they can be sampled correctly, nothing more. So, it's an inherent property of the design that input jitter makes no difference at all. Doing this is not expensive, and I don't regard the use of a crystal and an FPGA as fancy. I do, however, regard the topology as correct - and, fortunately for those of us with a working design with commercial potential, unusual. One day, all DACs will be made this way. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;238566 Wrote: What I do find surprising is that anybody designs a DAC that uses the SPDIF input as a timing reference rather that merely a source of bits. I've spent some of my spare time this year designing a DAC - based around the AK4396 as it happens - which makes no attempt to directly recover a clock from the SPDIF input. Incoming edges are used merely to identify where bits start and finish so they can be sampled correctly, nothing more. So, it's an inherent property of the design that input jitter makes no difference at all. How do you deal with buffer underrun/overflow due to differences in average clock rates between your DAC's oscillator and the source's? There's the rub, I think. -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Actually you'd be amazed just how hard it is to hear when a sample is dropped or duplicated - not that the final design ever actually does that, of course. I hope you'll forgive me for not disclosing all the inner workings of the design right now - it does seem to be a peculiar characteristic of hi-fi companies that they seem unusually willing to discuss their trade secrets in public. I guess there's a trade-off between maintaining a competitive advantage, and gaining credibility with an inquisitive customer base. As of this moment in time, though, my DAC is not available for sale - so I have no particular need to earn that credibility just yet by explaining the precise ins and outs. Hope you understand. I will say that the crystal I use is actually a VCXO, with a specified rms output jitter of 2.72 picoseconds, and that it's connected directly to the master clock input pin of the AK4396. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Andy I always imagined that by dumping the bits frame by frame into a buffer and then reading them out aysnchronously but with a very high-rez/low jitter clock, the end result would be good. Provided that the buffer never underruns then I see no reason why this wouldn't work. Since the sampling frequency is a given, there's no need to re-discover it from the the bitstream. Just grab the bits and feed them into the DAC nice and steady. I wish you success with your design - Phil -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... ...SB3+TACT+Altmann+MF DACXV3/Linn tri-amped Aktiv 5.1 system and some very expensive cables ;o) Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Thanks Phil :) I have a prototype and it works very well indeed. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Andy, that's fine - of course you don't have to discuss it. Phil Leigh;238596 Wrote: I always imagined that by dumping the bits frame by frame into a buffer and then reading them out aysnchronously but with a very high-rez/low jitter clock, the end result would be good. Provided that the buffer never underruns then I see no reason why this wouldn't work. Since the sampling frequency is a given, there's no need to re-discover it from the the bitstream. Just grab the bits and feed them into the DAC nice and steady. The problem is that the frequency of the input is -not- given, because each oscillator has a slightly different average frequency. So your local clock will never match the one that generated the input exactly, which means the buffer will eventually overflow or empty. Unless... unless you can vary the speed of oscillation of the DAC clock in response to the state of the buffer (slow it down if it's getting close to empty, speed it up if it's getting close to full, no adjustment if it's just right). That's how Lavry's DACs are supposed to work (although evidently the DA10 doesn't), and it sounds like that's what Andy is doing. -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
I must be missing something...the ORIGINAL sampling frequency is a given...let's say it's 44.1 kHz. So all you need to do is read those frames out at that frequency. Why exactly is that so hard? Assuming you never run out of frames to read. As far as I can understand things, the whole clocking problem comes about if - and only if - there is no buffer. If the design is synchronous end-to-end I can see how the clocks and clock drift and jitter can really mess things up. -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... ...SB3+TACT+Altmann+MF DACXV3/Linn tri-amped Aktiv 5.1 system and some very expensive cables ;o) Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
opaqueice;238603 Wrote: The problem is that the frequency of the input is -not- given, because each oscillator has a slightly different average frequency. So your local clock will never match the one that generated the input exactly, which means the buffer will eventually overflow or empty. (My comment isn't a criticism of anyone's previous posting.) This is like a lot of discussions of possible effects on sound quality. It poses a theoretical effect and proceeds directly to the solution. A couple of questions always come to my mind: 1. Does this effect actually occur to an extent that can be detected? 2. How big is the effect? For example how far off would an SB3 clock be from an perfect clock? In this case, I wonder just how much difference is there between the average rates of the clock locally generated in a buffered DAC and the clock used to transmit the SPDIF stream from a good quality sound card in a PC? Or the transmit clock in an SB3? If the difference is fairly small, then a simple approach using a fixed local clock and a reasonable sized buffer may in fact work well enough. Deleting quiet samples or inserting quiet samples in a string of quiet samples every now and then might provide periodic re-syncing of the transmit and receive clocks. Bill -- Listener Listener's Profile: http://forums.slimdevices.com/member.php?userid=2508 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Phil Leigh;238608 Wrote: I must be missing something...the ORIGINAL sampling frequency is a given...let's say it's 44.1 kHz. So all you need to do is read those frames out at that frequency. Why exactly is that so hard? Assuming you never run out of frames to read. As far as I can understand things, the whole clocking problem comes about if - and only if - there is no buffer. If the design is synchronous end-to-end I can see how the clocks and clock drift and jitter can really mess things up. It's just that no two oscillators give you exactly the same frequency. So suppose the DAC clock is slightly faster. Then when you hit play, maybe there's a slight pause to let the buffer fill a little, and then away you go. Since the DAC clock is faster after a while the buffer is completely empty, and then you have a problem. Listener;238610 Wrote: 2. How big is the effect? For example how far off would an SB3 clock be from an perfect clock? I looked this up once, and don't remember the numbers - but the answer is that it's big enough to cause problems, particularly on long tracks. Making the buffer bigger doesn't help you when the local clock is faster - unless you're willing to have a long pause before the music starts. And you have to remember that a good commercial DAC should be able to deal with quite a wide variety of digital sources. It wouldn't be a very good design if it depended crucially on how accurate the clock was in the source. How audible any of this is - that's another question :-). -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Phil Leigh;184095 Wrote: No optical is NOT inferior and is used extensively in certain professional circumstances. At the frequencies and distances involved in domestic digital applications this is a non-issue. In fact I would go as far as to say that optical is preferable in many circumstances due to the lack of galvanic coupling. This is one of the great audio myths of our time. (similar to all switching supplies are inherently flawed and jitter doesn't exist anymore because transports and DACs are so great) It is inferior, and it is not a myth. You are grossly uninformed. Galvanic isolation can be achieved by using transformers, althoough doing so requires some skill on the part of the designer. Of all the optical methods, TOSLINK is the worst. Single-mode fibre could be used effectively, but alas, the way it is commonly implemented is all wrong. (In case anyone actually cares, I helped to engineer the world's first single-mode long-haul fibre system. I may just have an idea what I am talking about. Not that the ignorant will care; they rarely are open-mended enough.) Pat -- ar-t http://www.analogresearch-technology.net ar-t's Profile: http://forums.slimdevices.com/member.php?userid=13619 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
ar-t;238344 Wrote: It is inferior, and it is not a myth. You are grossly uninformed. Pat, do you think it makes an audible difference? Going into a Benchmark DAC1 I can't hear any change; same with a NOS DAC I experimented with. -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
opaqueice;238369 Wrote: Pat, do you think it makes an audible difference? Going into a Benchmark DAC1 I can't hear any change; same with a NOS DAC I experimented with. That is actually a darn good question. A DAC that has all sorts of fancy reclocking and stuff may not sound much different with crappy interfaces. That is the purpose of all of that stuff, and why it costs more to implement. While the absolute amount of jitter may not be significantly worse for poor interfaces, the spectral distribution will be. And there is the key. Not all forms of jitter will sound exactly alike. Close-in jitter, or heavily data correlated will stand out more than random jitter, with an even spectral distribution. So, it will depend on the system. I know...sounds like a cop out, which leads to proliferation of brash statements like Well, I can't hear any difference, so it does not exist. With the Benchmark, I am not surprised. I talked to the guy from Audio Circle last night about how the modded unit sounded. He said that both transformer outputs were susbstantially better than stock, but they did not sound any different in relation to each other. He does have a fancy D/A box, with all of that fancy circuitry. So, from that, it seems plausible that gross interface problems are very audible, but minor ones are not. At least not on a fancy unit. As for the non-o/s one..I am not fond of them. Yes, they have a sound that appeals to many. I am not sure that they are capable of enough resolution to enable you to tell for sure. So, any thoughts regarding that one would be a pure guess. Based partially on bias, so I could be mistaken. Part of the misconception about the usefullness of optical interfaces comes from the bits is bits assumption. Even the poorest of TOSLINK connections will pass data, and probably at 99.99% accuracy. But that is a far cry from being able to extract the clock with a minimal amount of jitter. One of the problems comes from pulse dispersion. An optical output will have mulitple spectral lines, that travel at just a slightly different velocity, due the minute differences in the paths it takes to reach the RX end. This spreads out the pulse, which of course, mucks up the rise time. (And other stuff.) When things get interesting is when you pick the fibre up, and start to move it around! Yeah, I knowhow likely is that to happen when you are listening to music. Well, that happens to a lesser degree when it is just sitting there. When we were in the evaluation stages of that big fibre install, we fought amoung ourselves constantly over how the best way was to come up with a measurement for pulse dispersion. Single-mode fibre is NOT designed to work under 1 km or so. We were never able to resolve whether or not we could put 1 km of fibre on a spool, or if it had to be spread all over the lab, similar to how it would be in the field. Ah...but that would still require some bending of the fibre. Anyway...while we continued to argue about it, the system went in. We eventually sent one of our worst Ph.D. weenies to the field to measure it. He screwed up somehow, and not sure we ever got a number to compare. Too bad, because that would have answered our question. Not that any of that addresses your question, but it was rather funny for those of us involved. But it does highlight that fibre is not perfect. It has dispersion and reflection problems just like coax. Immune to EMI, generates no EMI, isolates things electrically. Has some problems of its own. Pat -- ar-t http://www.analogresearch-technology.net ar-t's Profile: http://forums.slimdevices.com/member.php?userid=13619 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi;238057 Wrote: Getting back to the original question, last Stereophile, review of Bel Canto DAC3, measurements section: JA names Toslink inherently jittery. So, there's nothing wrong with Toslink, huh? True, but in the same article he also said using a 20 FOOT length of generic plastic TosLink gave a sound that was hard to distinguish from the electrical connection (COAX) He also said using the TosLink from a SqueezeBox resulted in sound that kept distracting me from the computer ... Not sure if that means the DAC3 is excellent at dealing with jitter or that the TosLink connection produces insignificant jitter ... or maybe a bit of both ... ;-) -- USAudio SB3 CIAudio VDA-2/VAC-1 CIAudio PLC-1 CIAudio D-200 Revel Concerta F12 + SVS SB12-Plus USAudio's Profile: http://forums.slimdevices.com/member.php?userid=8580 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Getting back to the original question, last Stereophile, review of Bel Canto DAC3, measurements section: JA names Toslink inherently jittery. So, there's nothing wrong with Toslink, huh? -- 325xi sb3 || simaudio nova cdp simaudio moon i-5 revel performa m20 on *skylan* stands via acoustic zen matrix reference ii and acoustic zen satori sb3 audioengine 5 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi;186718 Wrote: Andy, I would be thrilled to know your findings. It's especially interesting because nearly all posters on the previous 10 pages declined the very possibility of Toslink connection to be more jittery then coax. Right, as promised! I've just finally got round to spending a few minutes with a digital source (my Marantz CD63, for what it's worth), an optical cable and a Toslink receiver of the type commonly used in offboard DACs, A/V amps and the like. For starters: here's the CD63's coaxial output: [image: http://www.cawte.nildram.co.uk/Jitter/cd63.jpg] The jitter is horrible - about 11ns, and strongly data dependent. In my professional opinion, its output driver is total rubbish, maybe even faulty. Nevertheless it does work when plugged into a DAC, so I presume it's not necessarily all that unusual. By contrast, the output from the inexpensive Toslink receiver is much cleaner - a nice square 3.3v CMOS signal with clean edges. Jitter is around 2ns, which still isn't very impressive, but in this case it is much better than the coax output. Other coax sources I've looked at are much cleaner. With my inexpensive 100MHz 'scope I can't actually see any jitter on the SB3's coax output at all, which is exactly how it should be. The CD63 does seem particularly bad. What is interesting is that wiggling the optical plug, or pulling it out slightly, does make jitter considerably worse - more so than I was expecting, and easily adding a couple of ns. So it would appear that, if you're bothered by the existence of jitter at this point in the system, you should worry about the quality of your optical cable and its connectors. If anyone's really bothered, I'll repeat the test with the SB3. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Eric Carroll;184206 Wrote: Wire them both up to the destination device. Cover your eyes and do something like the following (coopt the SO as an assistant): - have the assistabnt .. Did the same and was going to suggest that al do the same. I can't hear _any_ difference in my 1m run to my DAC. -- kphinney SB3 CIAudio DVA-2 JoLida 102B Omega Grand 6's BW 602 S2's PowerMac Zhaolu D2.5 AKG K501 kphinney's Profile: http://forums.slimdevices.com/member.php?userid=10409 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;184223 Wrote: Unless there's a good bottle of red wine involved, really. Try it out. You have to be chilled out to qualify for subjectively valid listening tests. Heaven knows what they hand out in audiophile mags. :-) Okay... I second that one to! -- kphinney SB3 CIAudio DVA-2 JoLida 102B Omega Grand 6's BW 602 S2's PowerMac Zhaolu D2.5 AKG K501 kphinney's Profile: http://forums.slimdevices.com/member.php?userid=10409 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie wrote: jeffmeh;186851 Wrote: Of course they can, but I will stand by my point. It is negligible without a highly revealing combination of system, room, speakers, and ears. It is probably negligible in most cases even where such a combination exists. Not sure it has to be a very accurate system - it simply has to happen to be a chain that happens to produce a more individually tailored and appealing sound based on the particular change in the chain. Absolutely. Digital problems tend to affect the sound in a certain way - I describe it as a loss of fluidity, a hardening of the sound, a loss of depth and sound stage. It may not be immediately obvious on first listen but listening fatigue quickly sets in. My personal theory is that this is caused by phase relationships getting mangled, particularly at high-frequencies. I heard a similar sound through a Rotel amp with a bad tone control design - even when supposedly bypassed, the tone controls sucked the life out of the sound. When I took them out of circuit, the amp totally changed - it became musical. I put this down to phase effects too. Anyway, my point is to agree with pablolie in that I don't think it necessarily needs a particularly accurate system to identify certain changes in the digital source. R. ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi;186512 Wrote: To summarise the overwhelming response - Toslink works according to specification, which no inherent production flaws, so there's no reason to avoid it, or even better, use coax only when Toslink isn't available. I didn't miss anything, right? Toslink works by shining an LED along a length of cable, which is then received by a phototransistor at the other end. The signal from this phototransistor is likely to be smaller and have less clearly defined on/off edges than the signal received at the end of a coax cable. Therefore, it is not unlikely that jitter at the input to the clock recovery circuit will be worse, and that in turn may mean that jitter at the DAC chip (where it matters) is also worse. Now the next step. Few mentioned here that quality of optical connector can cause problems. Any advise of how to discern a good quality optical cable from something with cheap flaky connectors? Is it a matter of particular brands, or whatever else? I presume I can't evaluate quality just by looking at the cable or its price tag, right? The connector in an optical cable doesn't really make any difference - it's just a mechanical thing designed to hold the fibre in place so that the light coming out of the end shines onto the phototransistor. I seriously doubt there's any performance difference at all between connectors - it's not like in an electronic system where the connector is actually a part of the signal path. The transparency of the cable itself and the quality of the cut ends might be important. Keeping it as short as possible will help. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;186654 Wrote: The connector in an optical cable doesn't really make any difference - it's just a mechanical thing designed to hold the fibre in place so that the light coming out of the end shines onto the phototransistor. With all due respect.. The cheap one that came with my DAC wouldn't even stay connected to the input on squeezebox. The one I tried defined generic, so YMMV. Do some models have a lock or other method to secure them? -- Skunk Skunk's Profile: http://forums.slimdevices.com/member.php?userid=2685 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
The free one that came with my PlayStation 2 clicks very positively into place - I assumed that would represent about the cheapest component available. The ability of consumer electronics manufacturers to shave a penny or two off a product never ceases to amaze me. Let me revise my assertion: provided it actually holds the end of the fibre in place, the type of connector used on a Toslink cable should make absolutely no discernable difference to sound quality. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;186694 Wrote: The ability of consumer electronics manufacturers to shave a penny or two off a product never ceases to amaze me. Yeah it kind of makes one wonder what's been shaved inside the box. Thanks for the info, looks like I should try a different cheap one. -- Skunk Skunk's Profile: http://forums.slimdevices.com/member.php?userid=2685 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;186611 Wrote: So don't even drive the car, just stick to brand dogma?? :-) Dude, may I say you drive me crazy? Do you really see only blacks and whites? I just say your so beloved empirical methods ARE necessary as a part of the whole, but not when used alone. A mere audition what taken out of context proves nothing. But add it to other ways to elaborate your system, and it may become quite useful information. -- 325xi 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;186654 Wrote: Therefore, it is not unlikely that jitter at the input to the clock recovery circuit will be worse, and that in turn may mean that jitter at the DAC chip (where it matters) is also worse. Oops, here we go again! So, Andy, what's your conclusion here - Toslink is more prone to jitter related problems then coax? AndyC_772;186654 Wrote: The connector in an optical cable doesn't really make any difference - it's just a mechanical thing designed to hold the fibre in place so that the light coming out of the end shines onto the phototransistor. I seriously doubt there's any performance difference at all between connectors - it's not like in an electronic system where the connector is actually a part of the signal path. The transparency of the cable itself and the quality of the cut ends might be important. Keeping it as short as possible will help. Do you think that flimsy connector can't cause cable cut end to be set up at slightly wrong angle against receiver, causing reflections, delays, etc? Oh, I mentioned quality of cut ends in one of my very first posts of this thread... One of cable makers confirmed they use plastic and not glass, therefore losses are higher, but they tested that with length under hundreds of meters it does keeps signal as per Toslink specs, so generic transparency shouldn't be a big deal for couple of meters cable. -- 325xi 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi;186710 Wrote: Oops, here we go again! So, Andy, what's your conclusion here - Toslink is more prone to jitter related problems then coax? Forgive me for side-stepping the question, but I think it would be pointless to guess without making some quantitative measurements on the electrical output from a typical Toslink receiver module. That said, I have made a couple of observations which may be relevant: - if you look at the end of a Toslink cable, the light coming out of it is fairly omnidirectional; there is no particular angle at which it suddenly looks much brighter than others. Therefore, it's unlikely that a misalignment of a degree or so would make much difference. - an opto-isolator designed to pass data at a couple of Mbits typically has rather slow rising edges on its output, because of the passive pull-up used to bring the output to a logic '1' in the absence of light from the LED. This would inherently tend to increase jitter - and a Toslink connection is basically just an opto-isolator with a particularly wide separation between the two halves. I will be looking into this properly in the not-too-distant future, so I'll post my findings if anyone's really bothered. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;186717 Wrote: ... an opto-isolator designed to pass data at a couple of Mbits typically has rather slow rising edges on its output, because of the passive pull-up used to bring the output to a logic '1' in the absence of light from the LED. This would inherently tend to increase jitter - and a Toslink connection is basically just an opto-isolator with a particularly wide separation between the two halves. I will be looking into this properly in the not-too-distant future, so I'll post my findings if anyone's really bothered. Andy, I would be thrilled to know your findings. It's especially interesting because nearly all posters on the previous 10 pages declined the very possibility of Toslink connection to be more jittery then coax. -- 325xi 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Having followed this thread, I am definitely more jittery than when I started. A purely subjective observation, YMMV. -- konut konut's Profile: http://forums.slimdevices.com/member.php?userid=1596 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Whichever is subject to more jitter, unless you have an extremely revealing system, very good speakers, a room with good acoustics, and some very keen ears, it is likely to be negligible. If you possess all of the above, I'm envious, lol. -- jeffmeh jeffmeh's Profile: http://forums.slimdevices.com/member.php?userid=3986 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
jeffmeh;186751 Wrote: Whichever is subject to more jitter, unless you have an extremely revealing system, very good speakers, a room with good acoustics, and some very keen ears, it is likely to be negligible. If you possess all of the above, I'm envious, lol. The original question was purely technical, as stated in one of the much earlier posts, I'm interested to know jitter difference regardless of it's audible or not. -- 325xi 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi;186709 Wrote: Dude, may I say you drive me crazy? Do you really see only blacks and whites? I just say your so beloved empirical methods ARE necessary as a part of the whole, but not when used alone. A mere audition when taken out of context proves nothing. But add it to other ways to elaborate your system, and it may become quite useful information. First of all, I was clearly kidding. Second of all, you must confuse me with someone else when it comes to the so beloved empirical methods. I actually have a very pragmatic approach when it comes to audio equipment. I like to understand some of the theories behind it, but then again I am very open minded, and fully aware of the emotional element of psychoacoustics that go into it - then again, I'll put a $ cap on the emotional stuff, there's not a single multi-thousand $ esoteric element in my chain. I'll buy a cable that's a couple $100 mostly because it looks cool, makes me feel good, and the money doesn't hurt - but try to sell me a $2,000 cable and I'll be get outta here - I'd rather fly to Cabo for the week!. Then again, I think controlled listening tests are *very* important. I have a pretty decent ear for differences. It's simply important to know and stand to one's sound preferences, and acknowledge that better sounds for me may not be better sound for someone else. Often the resolution and detail is identical, but some aspects of it are presented a bit different. I'll stand to my prefrence every time, and if I am able to detect a difference every time (like between the SB3's internal DA and the SB3-Toslink-AccuphaseDA chain), it's what ultimately makes me decide on a certain configuration. I'll grant what a listening test like that doesn't prove is utter linearity and perfect transparency - we may *prefer* somewhat distorted sound that compensates for our individual hearing etc. Then again, the fact that something comes out perfectly accurately our of the system does not mean it'll make it equally accurate into my brain. Besides, I'd really find if funny if some of those talking about Toslink jitter due to distorted flanks then prove to have a tube amp in their system. But that's the fun part of audio. :-) 325xi;186709 Wrote: BTW, if we were talking about BMW, then my answer to your question is definite yes. That's fine, but you can't claim that's a purely pragmatic choice then. There is a very irrational and emotional element to a priori brand preference - and it's totally fine. -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
jeffmeh;186751 Wrote: Whichever is subject to more jitter, unless you have an extremely revealing system, very good speakers, a room with good acoustics, and some very keen ears, it is likely to be negligible. If you possess all of the above, I'm envious, lol. Funnily enough, that's exactly what I thought about a year ago, when I confidently ditched my (early, and rather expensive) DVD player in favour of a cheap DVD recorder. I figured that all digitally connected sources should sound the same, and therefore, that I could play CDs using the DAC in my A/V receiver and they'd sound just as good as before. My old DVD player used a coax connection, the new one used Toslink. It took me about a week to realise that something was wrong. Music was boring, the soundstage rather flat and instruments hard to pick out individually - I just wasn't enjoying it any more. Sadly by this point my old DVD player had vanished at the hands of Ebay. So, I bought another one - a newer model well reviewed for its audio quality - and plugged it in with a coax connection. It sounds great, normal service is resumed. This isn't a controlled experiment, of course, but it does prove (to me, at least) that all digital sources are not equal. The same DAC and amp combination really can sound different when fed with a different source. Ironically it's the cheap recorder that's most tolerant of discs in poor condition, so I don't believe for a minute that bit errors are creeping in to cloud the issue. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;186759 Wrote: First of all, I was clearly kidding. Please accept my sincere apologies then. :) pablolie;186759 Wrote: Second of all, you must confuse me with someone else when it comes to the so beloved empirical methods. I actually have a very pragmatic approach when it comes to audio equipment. I like to understand some of the theories behind it, but then again I am very open minded, and fully aware of the emotional element of psychoacoustics that go into it - then again, I'll put a $ cap on the emotional stuff, there's not a single multi-thousand $ esoteric element in my chain. I'll buy a cable that's a couple $100 mostly because it looks cool, makes me feel good, and the money doesn't hurt - but try to sell me a $2,000 cable and I'll be get outta here - I'd rather fly to Cabo for the week!. Then again, I think controlled listening tests are *very* important. I have a pretty decent ear for differences. It's simply important to know and stand to one's sound preferences, and acknowledge that better sounds for me may not be better sound for someone else. Often the resolution and detail is identical, but some aspects of it are presented a bit different. I'll stand to my prefrence every time, and if I am able to detect a difference every time (like between the SB3's internal DA and the SB3-Toslink-AccuphaseDA chain), it's what ultimately makes me decide on a certain configuration. I'll grant what a listening test like that doesn't prove is utter linearity and perfect transparency - we may *prefer* somewhat distorted sound that compensates for our individual hearing etc. Then again, the fact that something comes out perfectly accurately our of the system does not mean it'll make it equally accurate into my brain. I see again that we basically have very similar views... I know I tend to react too harsh when I ask purely technical question, in attempt to have a purely technical answer, but the replies are try to listen. pablolie;186759 Wrote: Besides, I'd really find if funny if some of those talking about Toslink jitter due to distorted flanks then prove to have a tube amp in their system. But that's the fun part of audio. :-) You didn't mean me here, right? 8-0 The last tubed thing I had in my life was black-white TV 30 years back... -- 325xi simaudio nova cdp simaudio moon i-5 revel performa m20 via acoustic zen matrix reference ii and acoustic zen satori -planned additions:... deq2496 lavry da-10 ...- 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;186765 Wrote: Funnily enough, that's exactly what I thought about a year ago, when I confidently ditched my (early, and rather expensive) DVD player in favour of a cheap DVD recorder. I figured that all digitally connected sources should sound the same, and therefore, that I could play CDs using the DAC in my A/V receiver and they'd sound just as good as before. My old DVD player used a coax connection, the new one used Toslink. It took me about a week to realise that something was wrong. Music was boring, the soundstage rather flat and instruments hard to pick out individually - I just wasn't enjoying it any more. Sadly by this point my old DVD player had vanished at the hands of Ebay. So, I bought another one - a newer model well reviewed for its audio quality - and plugged it in with a coax connection. It sounds great, normal service is resumed. This isn't a controlled experiment, of course, but it does prove (to me, at least) that all digital sources are not equal. The same DAC and amp combination really can sound different when fed with a different source. Ironically it's the cheap recorder that's most tolerant of discs in poor condition, so I don't believe for a minute that bit errors are creeping in to cloud the issue. Actually, I was not referring to the differences between different sources, but between the same source connected via coax vs. toslink. -- jeffmeh jeffmeh's Profile: http://forums.slimdevices.com/member.php?userid=3986 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
jeffmeh;186773 Wrote: Actually, I was not referring to the differences between different sources, but between the same source connected via coax vs. toslink. Two different connection methods are comparable to two different sources. If one of the cases can sound different, so can the other. -- P Floding No, I didn't ABX it. And I won't even if you ask me. (Especially not if you ask me.) P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
P Floding;186832 Wrote: Two different connection methods are comparable to two different sources. If one of the cases can sound different, so can the other. Of course they can, but I will stand by my point. It is negligible without a highly revealing combination of system, room, speakers, and ears. It is probably negligible in most cases even where such a combination exists. -- jeffmeh jeffmeh's Profile: http://forums.slimdevices.com/member.php?userid=3986 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
jeffmeh;186851 Wrote: Of course they can, but I will stand by my point. It is negligible without a highly revealing combination of system, room, speakers, and ears. It is probably negligible in most cases even where such a combination exists. Not sure it has to be a very accurate system - it simply has to happen to be a chain that happens to produce a more individually tailored and appealing sound based on the particular change in the chain. Negligible is not a rational term - at least not to anyone that follows a forum under the term audiophile! A negligible difference to most is the *huge* difference to the audiophile!! At least that is the way I see it. I love the fact other people love the passion - I love to disagree with them because they do. :-) -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
OK, people - now, after everybody finally believed in jitter existence, can we return to the original subject? :) To summarise the overwhelming response - Toslink works according to specification, which no inherent production flaws, so there's no reason to avoid it, or even better, use coax only when Toslink isn't available. I didn't miss anything, right? Now the next step. Few mentioned here that quality of optical connector can cause problems. Any advise of how to discern a good quality optical cable from something with cheap flaky connectors? Is it a matter of particular brands, or whatever else? I presume I can't evaluate quality just by looking at the cable or its price tag, right? -- 325xi 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi;186512 Wrote: OK, people - now, after everybody finally believed in jitter existence, can we return to the original subject? :) To summarise the overwhelming response - Toslink works according to specification, which no inherent production flaws, so there's no reason to avoid it, or even better, use coax only when Toslink isn't available. I didn't miss anything, right? Now the next step. Few mentioned here that quality of optical connector can cause problems. Any advise of how to discern a good quality optical cable from something with cheap flaky connectors? Is it a matter of particular brands, or whatever else? I presume I can't evaluate quality just by looking at the cable or its price tag, right? You could try listening to it... -- Phil Leigh Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Phil Leigh;186516 Wrote: You could try listening to it... Phil, cable with flimsy connectors is to-be-defected cable, and not every defect can be revealed from the very first test. It may work OK first day, a week, a month... and then show me an intermittent problem, for which I won't know whom to blame, as I won't be able to reproduce it consistently... Besides, when I'm looking for a new car, I normally try to look deeper then into a sole driving test... Brands normally do well for me... -- 325xi 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Thank you Andy! I've been reading about jitter for years and your post was the best explanation ever. -- ebrandon ebrandon's Profile: http://forums.slimdevices.com/member.php?userid=10414 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
You should read what I write when I'm sober :) -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
seanadams;184848 Wrote: Not to go too far off the deep end here, but even if the transitions were infinitely steep and perfectly timed, it would be difficult to extract a clean clock. Due to zeroes having one fewer transition than ones, the receiving PLL will generate data-correlated jitter of its own as it drifts slightly between bits. Julian Dunn's J-Test paper describes how this works and how to reveal a receiver's worst-case behavior using a special square-wave signal, which is measured after the DAC. There are ways to minimize data correlated jitter by using an elaborate two-stage PLL, but even then it's still an analog circuit susceptible to noise. You could never do better than a local oscillator. Interesting. S/PDIF really is flawed... A question for those interested in getting as close as possible to audio perfection: it seems (for reasons discussed in this thread and many times before on this forum) that a SB or Transporter using its own DAC has a huge advantage over nearly any external DAC. Why do so few people here use it that way? It´s possible that with some very clever and complicated engineering an external DAC could overcome these problems, but why trust that it has when you have a much simpler and more elegant solution already available? -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
opaqueice;184856 Wrote: ... it seems (for reasons discussed in this thread and many times before on this forum) that a SB or Transporter using its own DAC has a huge advantage over nearly any external DAC. Why do so few people here use it that way? I think most have tested things out, and found out that for whatever reasons the setup they sttled for sounded the best. Jitter at the digital input certainly is not ever going to be the one and only thing that will result in differences coming out on the A end of a DA subsystem. And it stands to reason that more comproming DA designs may sound better than the DA of a $299 SQB despite possible clock mismatches of the separate components due to jitter. I did initial tests, and while the DA in the SQB seems very good, I somehow preferred the external DA option and could hear a clear difference. For one, due to my power setup I had a slight hum issue. I could easily solve it with very little work, but it hasn't been a priority because I am throughly pleased with the sound as it is now, a huge testament to the SQB, which has rendered a $7k CD system increasingly jobless. I'll revisit it later. -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
opaqueice;184856 Wrote: Interesting. S/PDIF really is flawed... A question for those interested in getting as close as possible to audio perfection: it seems (for reasons discussed in this thread and many times before on this forum) that a SB or Transporter using its own DAC has a huge advantage over nearly any external DAC. Why do so few people here use it that way? It´s possible that with some very clever and complicated engineering an external DAC could overcome these problems, but why trust that it has when you have a much simpler and more elegant solution already available? This is the reason I concluded, a year and a half ago, to go with a Red Wine modded SB3. Lately I have been thinking about getting an external DAC. Thanks for reminding me why this is an excercise in futility that will undoubtedly get me a 'different' sound though not nessesarily better. Need to buy more CDs!! -- konut konut's Profile: http://forums.slimdevices.com/member.php?userid=1596 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
opaqueice;184856 Wrote: Interesting. S/PDIF really is flawed... A question for those interested in getting as close as possible to audio perfection: it seems (for reasons discussed in this thread and many times before on this forum) that a SB or Transporter using its own DAC has a huge advantage over nearly any external DAC. Why do so few people here use it that way? While I agree that S/PDIF is a flawed interface, those flaws do not necessarily produce any audible degradation of sound. (They may or may not depending on a host of other system factors.) And I would hardly say that an internal DAC as a huge advantage. It has a slight advantage, which in my system, at least, is insignificant compared to the disadvantages of the SB3's internal DAC. The analog output of DAC in my SB3 sounds noticeably inferior to the S/PDIF optical digital output routed to my external DAC (using the same interconnects to the amp for both). This isn't a case of needing ABX double blind testing to distinguish whether or not very subtle perceived differences are real. The external DAC flat out smokes the SB3's internal DAC, even using the flawed S/PDIF. I would happily give up the external DAC if that wasn't so. Now, if I had a Transporter, things might be different... -- TiredLegs TiredLegs's Profile: http://forums.slimdevices.com/member.php?userid=6201 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Robin Bowes;184379 Wrote: pablolie wrote:[color=blue] It's digital data, but it's sent over an analogue transmission path. The 1s and 0s are converted to different voltages and the resulting signal sent down the cable. At the other end, the receiver reads the signal and converts the different voltages into 1s and 0s. If the signal on the cable gets distorted in any way then the signal produced by the receiver may not match that fed into the transmitter. R. It's *data*. Data integrity is the key. It does not matter of the signal gets somewhat distorted. That's actually one of the key advantages of digital interfaces: you don't have to worry as much over signal integrity. It's no misconception at all. An ugly bit is still a bit. -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;184524 Wrote: It's *data*. Data integrity is the key. It does not matter of the signal gets somewhat distorted. That's actually one of the key advantages of digital interfaces: you don't have to worry as much over signal integrity. It's no misconception at all. An ugly bit is still a bit. That isn´t true. It´s a digital stream, but the DAC uses transitions to construct a clock, and therefore variations in the timing of the bits will affect the clock and distort the analogue output. That will happen even if there are zero bit errors - so an ugly bit, while still a bit, is a problem for S/PDIF. -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie wrote: It's *data*. Data integrity is the key. It does not matter of the signal gets somewhat distorted. That's actually one of the key advantages of digital interfaces: you don't have to worry as much over signal integrity. It's no misconception at all. An ugly bit is still a bit. I'm afraid you're wrong. I suggest you read up on how SPDIF works and the potential weaknesses inherent in its design. R. ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Robin Bowes;184562 Wrote: pablolie wrote: It's *data*. Data integrity is the key. It does not matter of the signal gets somewhat distorted. That's actually one of the key advantages of digital interfaces: you don't have to worry as much over signal integrity. It's no misconception at all. An ugly bit is still a bit. I'm afraid you're wrong. I suggest you read up on how SPDIF works and the potential weaknesses inherent in its design. R. SPDIF is BMC encoded, and *digital*. Please tell us what's wrong about that. Consequently, the quality of the phyiscal signal has to be quite compromised for a bit error to occur, and until a bit error occurs the signal issues are immaterial. Truly. You seem to disagree about the probability of that happening, but to argue ver the fact that the data is encoded digitally is lunacy. Of course there will always be analog effects at the signal transmission level, and those have been discussed in this forum when the merits of RCA and Toslink were compared. That's where the signal quality discussion kicks in. Other than that I truly have no idea what analog effect you should be talking about: we ought to simply be worried whether your 20 bit (or 24) audio data stream emerges identical on the remote end as it is presented to the DAC subystem. The fear seemed to be the data goes into the DAC subsystem with additional jitter if the Toslink connector is used. You seem to be introducing a data integrity element that as far as I have seen no one has brought up, since the interface is quite resilient at that level, irrespective of the interface type used for transmission. -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
SPDIF is BMC encoded, and therefore *digital*. Absolutely 100% wrong. The _TIMING_ information which is carried by s/pdif is an analog signal in the truest sense, not just on the wire but from end to end. Are you really questioning that? -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
What a lovely thread - it has passion, enthusiasm and complete BS all rolled into one :) Let me try to clear some of it up; apologies to those of you for whom this is all basic stuff, but I've yet to see a good explanation of signal integrity in an audiophile forum, and there's an awful lot of vagueness and pedantry around with remarkably little science to back it up. With any digital data link, there are always two aspects to consider: the data itself, and the associated clock. Let's consider them separately for a moment. The data is the easy bit. It's just ones and zeroes, and as long as there isn't so much noise on the wire that they actually get misinterpreted, it's easy to reliably recover -exactly- what was transmitted. It doesn't matter whether they originally came from a CD, or a file on a hard disc, or over an Ethernet or wireless connection. Then there's the clock, which is more complicated. In some communications systems, the clock is carried on a separate wire, and the receiver samples the data whenever the clock changes from low to high or from high to low. If all you're doing is storing the data in memory or forwarding it on to another device, that's all there is to it. As long as the clock transitions line up with the data bits, the link works. Zero degradation. In many modern systems (Ethernet, USB, S/PDIF), no separate clock wire is used. Instead the clock is recovered by looking at the timing of transitions in the data. In the case of something like Ethernet, where all you care about is getting the data from A to B reliably, this also works fine. The problem comes when you have to start caring about not just getting the bits from A to B, but also about exactly when they arrive at their destination. This is the problem with S/PDIF - you need to play the music at the same rate it comes in. A CD is sampled at 44.1kHz. But, no oscillator in the world (and certainly, no oscillator in your hi-fi) ticks at precisely that speed. Standard tolerance on a quartz crystal is +/-50 parts per million, which is no problem in itself - you can't hear the difference if you CDs are played back at 44.1002205kHz instead. However, say your DAC were running 50ppm fast and your CD transport (or whatever) were 50ppm slow. About 4 times per second the DAC won't have a sample to play, and you might hear this as a click. Not very hi-fi, I'm sure you'd agree. So, there has to be a mechanism to ensure that the clock in the DAC runs at precisely the same speed as the one in the source component. Because S/PDIF is unidirectional - it only provides a path from source to DAC and not the other way round - it has to be this way. When music is digitised, samples are taken at precisely determined intervals by very expensive studio equipment, and so to reproduce the original signal as accurately as possible, the output from the DAC has to be updated equally precisely, so that the time interval between successive samples is the same as it was originally. Variation in this period between samples is what we all know and love as jitter. [/i]The only place this jitter matters is at the DAC chip itself.[/i] In a device like a Squeezebox, big bursts of data are sent over the network into a buffer memory, then it's broken into smaller packets and stored in a FIFO (first in, first out) buffer by the CPU, and finally clocked into the DAC a bit at a time at regular intervals. It's only at the point where the last bit is clocked in and the DAC updates that jitter makes any difference whatsoever. If an external DAC is in use, it's only the clock pulse that causes that DAC chip to update that matters. Jitter elsewhere is basically a non-issue. What does this have to do with S/PDIF? This is all down to implementation. For the reasons explained above, a circuit in the DAC has to recover the clock from the S/PDIF signal and, from this, generate a clock to the DAC which is synchronised and yet has the least amount of jitter possible. Typically this is done with a circuit called a Phase-Locked Loop or PLL, and although they're very good at rejecting jitter, they're not perfect. The more that's fed in, the more comes out. So, jitter on the S/PDIF link can lead to jitter at the DAC input, which in turn can affect the sound. That's why all S/PDIF links are not equal :) The ideal is to have the master clock located in the DAC, not the source. Then you can have a high quality, stable oscillator right by the DAC chip itself, where it matters. But S/PDIF doesn't allow for this, because there's no way for the DAC to control the rate at which data is transferred. Bidirectional links like Ethernet, USB and Firewire get around this problem. (I have a USB connected headphone amp at work with its own built-in DAC. It sounds wonderful!). Optical vs coax? Both can give rise to unwanted jitter. With an optical cable, the signal from the phototransistor in the receiver (which is what matters) is fairly small and its rise/fall time isn't
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;184693 Wrote: ... Hope that helps a bit :) Andy This thread is over. You put it perfectly. -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
ps. I can tell the difference between a poor digital transport connected via an optical lead, and a good one connected by coax. Last year I replaced my high quality (but early and buggy) DVD player with a cheap recorder. I was convinced that they'd sound identical played through the same external DAC. It took me about a week to work out that I just wasn't enjoying the music any more. The soundstage was flat and it was hard to pick out individual instruments. One used, high-end universal player from Ebay later, normal service is resumed. The Squeezebox sounds pretty good too :) -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
This is so well understood and so easily observed that I just don't know what to say. It's as if you're pointing at the sky screaming it's red and expecting a meaningful argument. I wonder if you're just trolling, and the joke is on me. Also, my comments in the other thread about the audibility of small levels of incremental jitter do not make the phenomenon cease to exist. But that was a nice try. -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;184694 Wrote: have you truly claimed analog transmission elements that do *not* affect SPDIF bit integrity still have an effect? i could imagine reasons why that´s that case in a real world implementation, but that has little to do with the SPDIF protocols... Yes of course they do, and it has everything to do with the S/PDIF protocol. That´s a basic fact about synchronous digital transmission; it´s called jitter. It can have a dramatic and easily audible effect (although it can also be controlled and rendered inaudible with modern techniques). No offense, but you´ve demonstrated a rather basic ignorance of this subject numerous times in this thread. I suggest you do some research before posting again. -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
seanadams;184699 Wrote: It's as if you're pointing at the sky screaming it's red and expecting a meaningful argument. I wonder if you're just trolling, and the joke is on me. I'm sorry - if everyone understands all this already and I'm the ignorant one for not realising it, then I humbly apologise. But, as an outsider looking in, I sometimes read stuff on hi-fi forums that (to me!) seems to illustrate a lack of understanding of the fundamentals behind how a digital system works. That's not meant as a criticism BTW; I've been reading car tuning forums for the last few years and have a reasonable idea about how people go about getting more power from an engine - but that doesn't mean I could actually tune my own car, and I certainly couldn't design a better engine from scratch. I greatly admire those people who can. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;184705 Wrote: I'm sorry - if everyone understands all this already and I'm the ignorant one for not realising it, then I humbly apologise. But, as an outsider looking in, I sometimes read stuff on hi-fi forums that (to me!) seems to illustrate a lack of understanding of the fundamentals behind how a digital system works. Could you be more specific about what you don´t understand? If it´s how an S/PDIF stream with no bit errors can produce a distorted signal, read any article about jitter in digital audio. Possibly you´re used to asynchronous digital protocols like TCP/IP (which are very different). -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;184705 Wrote: I'm sorry - if everyone understands all this already and I'm the ignorant one for not realising it, then I humbly apologise. But, as an outsider looking in, I sometimes read stuff on hi-fi forums that (to me!) seems to illustrate a lack of understanding of the fundamentals behind how a digital system works. That's not meant as a criticism BTW; I've been reading car tuning forums for the last few years and have a reasonable idea about how people go about getting more power from an engine - but that doesn't mean I could actually tune my own car, and I certainly couldn't design a better engine from scratch. I greatly admire those people who can. That was to pablolie, not you. Sorry, I should have quoted. Your explanation was fine. Thanks for taking the time to post it. -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Guys, I think your postings all crossed in mid-write and we are having a clock slip here ;-) I think sean was responding to pablolie not Andy. I think Andy's response to sean was because he thought it was to him not pablolie (sean's posts overlapped a couple). And opaqueice did you mistake Andy's posting for the subthread you were having with pablolie? I suggest a quick look backwards - I am just forcing the clock resync. :-) -- Eric Carroll Transporter-Bryston 3B SST-Paradigm Reference Studio 60 v.4 SB3-Rotel RB890-BW Matrix 805 SB3-Pioneer VSX-49TXi-Mirage OM7+C2+R2 ReadyNAS NV+ Eric Carroll's Profile: http://forums.slimdevices.com/member.php?userid=9293 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;184698 Wrote: :) (disclaimer: I'm a professional electronic engineer specialising in communications systems... so I -ought- to know what I'm talking about!) I am an electrical engineer myself, but went off into the marketing side of things. So I am paid to make overzealous claims. :-) -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
D'uh! I'm easily confused, especially after a hard day at work and a beer or two... thanks guys :) -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
seanadams;184699 Wrote: ... do not make the phenomenon cease to exist. ... what phenomenon? i can't recall anyone talking about a phenomenon. other than possible you carrying a grudge over being caught making too generic a claim about memories. which would be disappointing. -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
opaqueice;184700 Wrote: Yes of course they do, and it has everything to do with the S/PDIF protocol. That´s a basic fact about synchronous digital transmission; it´s called jitter. Yeah, and SPDIF carries the data to overcome it. It is not a matter of the protocol, it's a matter of implementation. And that's why DACs have an input buffer. Jitter at the SPDIF layer should not be an unsurmountable issue. But no one disputes it can be an issue with a flawed design. # It can have a dramatic and easily audible effect It can. With a well implemented design it shouldn't. Someone else out there can tell us whether the good DAC chipes have an input buffer or not to avoid starvation. Basic voice communication codecs from 10 years ago did, so I am pretty sure DAC designers would take starvation issues into account. # I suggest you do some research before posting again Thanks. I suggest you provide useful information instead of just going ad hominem, because I haven't seen you make a point. -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
P Floding wrote: Isn't the Benchmark DAC1 supposed to reject all jitter due to propritary (correct!?) use of its ASRC? The Benchmarks folks do claim that it is immune to jitter. I don't know if it is real, or just marketing. I do know it sounds great to me. As does my Transporter -- Pat http://www.pfarrell.com/music/slimserver/slimsoftware.html ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Eric Carroll;184313 Wrote: And, by the way, its not an assumption, I said there are papers on this issue. For example, 'here is a paper on this issue.' (http://www.jstage.jst.go.jp/article/ast/26/1/50/_pdf). There are others I don't have handy right now. Unfortunately studies of the effects of _random_ jitter have little significance when it comes to correlated jitter. There are other issues with the test you are refering to -such as the simulation of jitter effects. -- P Floding No, I didn't ABX it. And I won't even if you ask me. (Especially not if you ask me.) P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Phil Leigh;184345 Wrote: Sorry Eric - I didn't mean to steal your thunder! I use to believe that toslink was bad too - until I realised what I had in my studio was piles of the stuff! (ADAT lightpipe anyone?)...that started me thinking...and testing...and now I don't care - both work fine most of the time...but sometimes toslink can help (certainly my studio benefitted from the removal of certain ground loops! - and that strange tingling feeling when you brush against a rack full of gear at slightly different ground potentials...) Anyway, on the other hand, I do feel that jitter (especially synchronous jitter) is still a problem today. In the studio of course most gear is wordclocked...which helps! But the bad effects of jitter are only actually realised during the analogue conversion (until then, bits are just bits) so provided you minimise it just before that point... Your last point is not quite true nowdays, with ASRC and other asynchrounous digital domain processing going on. -- P Floding No, I didn't ABX it. And I won't even if you ask me. (Especially not if you ask me.) P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;184348 Wrote: He stated what *really* matters: The identical framing protocol (S/PDIF) runs on top of both optical and coax, meaning you'll get identically timed data out of the two - whatever jitter there is at a physical layer is immaterial. The clock is embedded into the signal via BMC. BMC provides a very solid clock for synchronization. The jitter thus doesn't matter, nor does noise in coax, by the way - this is digitally encoded data and thus remarkably noise resistant. If interface jitter rejection is good at the DAC, this would be correct. Unfortunately digital audio is badly engineered from the very start since jitter effects weren't understood at the time of designing the SPDIF interface. Today we live with at variety of equipment with varying susceptibility to SPDIF jitter. -- P Floding No, I didn't ABX it. And I won't even if you ask me. (Especially not if you ask me.) P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;184686 Wrote: Biphase Mark Coding is encoding for *digital* data, plus the frequency of the clock is twice the frequency of the original signal. The result is that at the physical level it's not about 0 and 1, but about even simpler polarity changes, which makes data *and* clock *easier* to recover. I never claimed there are no analog elements at the transmission layer - my point is that analog signal integrity is less critical for sound purity than with pure analogue signal transmission. Are you questioning that? Truly don't know what we're arguing about here? Are you claiming digital data transported via SPDIF is prone to bit errors? Are we back to the jitter issue, which you labeled immaterial yourself? Or are you saying that signal integrity is just as critical for purity in the pure analog as it is in the digital domain, as the person I was countering seemed to maintain? I think the OSI layers are getting mixed up in there discussions. At the lowest physical layer, there'll always be analog effects. but the interface to the data link layer is purely digital, and as long as it presents the same digital information for the higher layers to process whatever signal distortion at the physical analog level does not matter an ounce provided everything is properly contained in its respective module. Easier said in theory than done in practise. How is that saying now? A little knowledge kan be a dangerous thing? I bet you can't even imagine the flaws inherent to the old SPDIF system. -- P Floding No, I didn't ABX it. And I won't even if you ask me. (Especially not if you ask me.) P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
P Floding;184737 Wrote: Your last point is not quite true nowdays, with ASRC and other asynchrounous digital domain processing going on. Yes - true - which is exactly why I found that there was a big improvement when I stuck the Altmann JISCO+UPCI after my TACT, just before the input of the DAC...it seems to deal with the extra jitter coming out of the TACT ASRC process... I was thinking of the general case without ASRC. -- Phil Leigh Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Thanks :) TCP/IP is a higher level protocol anyway - it really couldn't have less to do with S/PDIF and its limitations. You could run TCP/IP over a pair of S/PDIF links (one Tx, one Rx) if you really wanted. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
P Floding;184744 Wrote: Did you read AndyC_772's postings? He explains that the way SPDIF works makes it impossible to have the master clock at the DAC, and hence the amount of interface jitter rejection is implementation dependent. Which is how it is. I'd ask all engineering types who think they know things without actually reading up on the subject to please go and read up first. (And, yes, I am an EE too, AND an audiophile. And, no, I don't believe in alternative woodoo laws of physics, nor do I believe we now got it all figured out and can lay back and stop questioning.) (General comment, not directed at you opaqueice!) Best regards Yes but...it is entirely possible to remodel the clock at the DAC input (ie right on the SPDIF socket) - see here http://www.altmann.haan.de/jitter/english/engc_navfr.html -- Phil Leigh Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Phil Leigh;184748 Wrote: Yes but...it is entirely possible to remodel the clock at the DAC input (ie right on the SPDIF socket) - see here http://www.altmann.haan.de/jitter/english/engc_navfr.html That's not entirely correct, though. That little gadget may attenuate jitter at the S/PDIF socket, but that's not the same as reducing jitter at the DAC where it matters. It's reducing jitter at the entry to the box that contains the DAC, which is not the same thing. There will still be a PLL or VCXO circuit between the S/PDIF socket and the DAC chip itself. In fact, if the transport is well designed and has low output jitter, then the Altmann gadget is really just removing the jitter resulting from signal degradation in the cable. The stuff on www.lessloss.com is, on the other hand, very accurate and a good read. -- AndyC_772 AndyC_772's Profile: http://forums.slimdevices.com/member.php?userid=10472 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Phil Leigh;184748 Wrote: Yes but...it is entirely possible to remodel the clock at the DAC input (ie right on the SPDIF socket) - see here http://www.altmann.haan.de/jitter/english/engc_navfr.html A lot of things are possible. But those claiming that SPDIF is a non-issue are not talking about what is possible, but what they think is the current state of things. -- P Floding No, I didn't ABX it. And I won't even if you ask me. (Especially not if you ask me.) P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
AndyC_772;184754 Wrote: That's not entirely correct, though. That little gadget may attenuate jitter at the S/PDIF socket, but that's not the same as reducing jitter at the DAC where it matters. It's reducing jitter at the entry to the box that contains the DAC, which is not the same thing. There will still be a PLL or VCXO circuit between the S/PDIF socket and the DAC chip itself. In fact, if the transport is well designed and has low output jitter, then the Altmann gadget is really just removing the jitter resulting from signal degradation in the cable. The stuff on www.lessloss.com is, on the other hand, very accurate and a good read. Well yes but... In my setup, I have 2 coax cables and a TACT rcs between my sb3 and DAC - plenty of opportunity for jitter to be added to the low levels coming out of the SB3. Also, the whole point is that not much jitter is added between the spdif socket and the DAC chip...the fact that there is a PLL en route is neither here nor there. -- Phil Leigh Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;184727 Wrote: It can. With a well implemented design it shouldn't. Someone else out there can tell us whether the good DAC chipes have an input buffer or not to avoid starvation. Basic voice communication codecs from 10 years ago did, so I am pretty sure DAC designers would take starvation issues into account. I agree with your first statement, but an input buffer (which all DACs - including those in CD players - must have in order to function) does nothing in itself to resolve this problem. You still need to generate a clock from somewhere, and if you use the transitions in the input for that you´re still sensitive to jitter. There are some easy but inconvenient ways to make a DAC that is completely insensitive to input jitter (for example buffer the entire input and then clock it out with a crystal), and some hard but convenient ways as well (see e.g. the Lavry whitepaper for the DAC10). AndyC - sorry, ignore my earlier post. -- opaqueice opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
opaqueice;184798 Wrote: I agree with your first statement, but an input buffer (which all DACs - including those in CD players - must have in order to function) does nothing in itself to resolve this problem. You still need to generate a clock from somewhere, and if you use the transitions in the input for that you´re still sensitive to jitter. There are some easy but inconvenient ways to make a DAC that is completely insensitive to input jitter (for example buffer the entire input and then clock it out with a crystal), and some hard but convenient ways as well (see e.g. the Lavry whitepaper for the DAC10). AndyC - sorry, ignore my earlier post. Quite! - but that only works if you wordclock the DAC to the transport. Anything less is just a guess... -- Phil Leigh Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;184727 Wrote: Basic voice communication codecs from 10 years ago did, so I am pretty sure DAC designers would take starvation issues into account. How old do you think the CD system is? Getting close to 30 years now, I believe. I know the problem at hand is EASILY solved, but you make the logical error of assuming that so has been done in all modern audio equipment. This is simply not true. A one-box solution, like the SB, solves this problem, but it would be nice if SPDIF-usage was better implemented. -- P Floding No, I didn't ABX it. And I won't even if you ask me. (Especially not if you ask me.) P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie wrote: opaqueice;184700 Wrote: # I suggest you do some research before posting again Thanks. I suggest you provide useful information instead of just going ad hominem, because I haven't seen you make a point. Let me make a point: you don't know what you're talking about. SPDIF transmits digital data over an analogue transmission line. The receiver must extract the clock signal from the signal it receives. Now, in an ideal world, this wouldn't be a problem - the signal received would have nice square edges and it would be easy to determine precisely when each sample occurs and, hence, construct the clock signal. However, because SPDIF is transmitted over an analogue path, the signal received does *not* have square edges so it is possible that the clock signal extracted from the stream is not 100% accurate. As (several) others have pointed out, you obviously just don't get this. Now, you can continue to point at the sky and scream it's red if you like, but the fact is, you're wrong, and you need to go and read up on the SPDIF specification and the inherent problems it has. I have no more to say on the matter. R. ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Robin Bowes;184814 Wrote: However, because SPDIF is transmitted over an analogue path, the signal received does *not* have square edges so it is possible that the clock signal extracted from the stream is not 100% accurate. R. i have not claimed the extracted signal is always accurate, or that errors aren't possible. but the fact the encoded signal is digital makes it more resilient, it's one of the whole friggin' advantages of digital data, foe heavens sake. that's telecom 101. that and nothing else has been my point. since the analog signal quality can vary more without affecting the data integrity an ounce, as would be the case with a total analog transmission. that is and has been my point. and not sure where you heard me claim the analog signal has or is supposed to have square edges. and if you're trying to claim you need a perfectly clean signal to extract clocking information... well, really. time's too precious. arrogance blends more credibly without blatant reading comprehension issues. -- pablolie pablolie's Profile: http://forums.slimdevices.com/member.php?userid=3816 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Robin Bowes;184814 Wrote: Now, in an ideal world, this wouldn't be a problem - the signal received would have nice square edges and it would be easy to determine precisely when each sample occurs and, hence, construct the clock signal. Not to go too far off the deep end here, but even if the transitions were infinitely steep and perfectly timed, it would be difficult to extract a clean clock. Due to zeroes having one fewer transition than ones, the receiving PLL will generate data-correlated jitter of its own as it drifts slightly between bits. Julian Dunn's J-Test paper describes how this works and how to reveal a receiver's worst-case behavior using a special square-wave signal, which is measured after the DAC. There are ways to minimize data correlated jitter by using an elaborate two-stage PLL, but even then it's still an analog circuit susceptible to noise. You could never do better than a local oscillator. Of course, in an _ideal_ world we would have perfect PLLs, so I guess it would be a non-issue. :) Incidentally, this test is what Stereophile and others use, and while it is a very clever test that can be performed without any exotic gear, it unfortunately has been applied far beyond its intended purpose. I've seen it used even to characterize devices that don't have s/pdif inputs! I suspect this is where the unfortunate, widely believed notion that jitter is a number comes from. -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
pablolie;184215 Wrote: I hear your pain given recent events around a question I asked! :-) But if you read between the lines, I think the answer is Toslink is not flawed. The same interface works in applications demanding high resiliency, is all I can say. I don't think anything's flwaed about the interface - any weaknessses have to be attributed to the application running on top... Interesting, my understanding is quite opposite... Eric mentioned that consumer Toslink does have higher jitter, but because of his assumption we can't perceive jitter less then ridiculously high :) +-0.5ns (that were nanoseconds, right?) he expressed his little concern about that. I've already said what I think about inaudibility assumptions. I'm somewhat concerned with that massive feedbacks that people don't like Toslink, we may define it BS, but I'm not sure those complains are totally baseless... So I'm Googling to find out... -- 325xi simaudio nova cdp simaudio moon i-5 revel performa m20 via acoustic zen matrix reference ii and acoustic zen satori -planned additions:... deq2496 lavry da-10 ...- 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi wrote: Eric mentioned that consumer Toslink does have higher jitter, [snip] I've already said what I think about inaudibility assumptions. I'm somewhat concerned with that massive feedbacks that people don't like Toslink, we may define it BS, but I'm not sure those complains are totally baseless... I can detect zero different when my SqueezeBox was feeding my Benchmark DAC-1. I believe the bad reputation is more caused by the fact that consumer Toslink is designed and used in consumer products. Quality is not the driver in that market, price and features are. -- Pat http://www.pfarrell.com/music/slimserver/slimsoftware.html ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Good! Can you guys tell me why didn't you replaced all your coax connections with Toslink - theoretically Toslink blows coax out of the water? -- 325xi simaudio nova cdp simaudio moon i-5 revel performa m20 via acoustic zen matrix reference ii and acoustic zen satori -planned additions:... deq2496 lavry da-10 ...- 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi;184284 Wrote: Eric mentioned that consumer Toslink does have higher jitter, but because of his assumption we can't perceive jitter less then ridiculously high :) +-0.5ns (that were nanoseconds, right?) he expressed his little concern about that. I've already said what I think about inaudibility assumptions. I'm somewhat concerned with that massive feedbacks that people don't like Toslink, we may define it BS, but I'm not sure those complains are totally baseless... So I'm Googling to find out... Please don't misquote me. I didn't say that at all. I am saying the following: 1. toslink works. 2. Issues with plastic fibre and connectors were problems with consume grade equipment over a decade and half ago. These kinks have been resolved. 3. there is no *data* to support it does not work that I have seen, and I have looked. 4. S/PDIF is a protocol that runs almost the same on fibre, coax and balanced lines (AES/EBU). If S/PDIF is broken then all three are broken. No audiophile argues that coax is broken, just toslink (S/PDIF on fibre). 5. There is no engineering rationale to argue that fibre is worse than coax even on plastic fibre. 6. SD PUBLISHES their S/PDIF jitter tolerance for the Transporter. It is 35ps. This is stunningly low. 7. SD measured the jitter of the SB2 and published it in this forum. It was around 65ps as I recall. 8. Much of this whole discussion was triggered by Stereophile article quoted above. See the Audio Critic rebuttal. And I didn't say nanoseconds, I say microseconds. And, by the way, its not an assumption, I said there are papers on this issue. For example, 'here is a paper on this issue.' (http://www.jstage.jst.go.jp/article/ast/26/1/50/_pdf). There are others I don't have handy right now. In other words, if you accept scientific investigation of this issue, then the achieved jitter of S/PDIF using the SD equipment is many orders of magnitude better than the requirement. I have not yet seen an audiophile arguement on this issue backed up by actual data or a study of any kind. I have only seen claims of personal listening preference and the Stereophile article, both of which echo around alot. If you don't believe in audibility testing and don't accept the scientific basis of looking into this issue, then we don't have common ground for further discussion. Feel free to select whichever one you have a personal preference for. Right now we are at the edge of the subjectivist/objectivist argument, and I won't enter into that. Good! Can you guys tell me why didn't you replaced all your coax connections with Toslink - theoretically Toslink blows coax out of the water? I preferentially use toslink, but a) it is more expensive b) not all my gear has optical connections c) not all my gear has coax connections d) some of my gear has more of one than other So I use both. -- Eric Carroll Transporter-Bryston 3B SST-Paradigm Reference Studio 60 v.4 SB3-Rotel RB890-BW Matrix 805 SB3-Pioneer VSX-49TXi-Mirage OM7+C2+R2 ReadyNAS NV+ Eric Carroll's Profile: http://forums.slimdevices.com/member.php?userid=9293 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
As I think I mentioned before, I have a friend (who is an engineer by profession) who owns a company that makes fibre for many of the big telcos and ISPs...he also likes his hi-fi... He did fall off his chair laughing...I had to buy him another drink! Toslink over 5 metres is absolutely fine for the (relatively) pathetic bandwidth/response requirements of SPDIF. Even plastic is fine. In some setups, coax (BNC or RCA) or even AES/EBU causes issues that don't exist with toslink. This is a result of earth loops and/or RFI Injection via the cable/terminations. However this is all pretty small beer in the scheme of things. After all, many of the CD's we listen to carry audio that has been down an optical fibre interface or two at some point in its develpment :o) -- Phil Leigh Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Eric Carroll;184313 Wrote: Please don't misquote me. I didn't say that at all. I didn't cite you, I said that was my understanding, which well might be erroneous. Eric Carroll;184125 Wrote: c) yes, it is possible some manufacturer fubared their design. If so its not TOSLINKs fault as a design. Bad cables impact networks the world over. But in a .5-1 MHz signal regime the cable has to be pretty appaling. d) This is the kicker. If you think that you need +-100ps jitter control on a TOSLINK connection than there is no way a LED and plastic can achieve that. If you think you need +-.5us I don't see how it couldn't achieve it. Its all in the requirements you believe a TOSLINK has to achieve. This is what I was talking about. I didn't mean to say that Toslink doesn't work on paper. I thought that so wide rejection of Toslink might originate in real world part quality, and may be that belongs to a past - I don't know. As for jitter - you said that about +-100ps. I never claimed I need 100ps or 500ps in particular, but I'm interested to find out the limit of jitter control of LED-plastic toslink vs. coax - please note - regardless of its audibility. Eric Carroll;184313 Wrote: And, by the way, its not an assumption, I said there are papers on this issue. For example, 'here is a paper on this issue.' (http://www.jstage.jst.go.jp/article/ast/26/1/50/_pdf). Very interesting paper, it answers on some of my concerns. Too bad they didn't make it fine enough between 500 and 250ns - I'd be curious to know. Eric Carroll;184313 Wrote: If you don't believe in audibility testing and don't accept the scientific basis of looking into this issue, then we don't have common ground for further discussion. Feel free to select whichever one you have a personal preference for. Right now we are at the edge of the subjectivist/objectivist argument, and I won't enter into that. You really don't have to be arrogant to sound convincing. I'm not believer at all. And of course I accept scientific basis. I don't believe in listening tests unless arranged in a proper way. The test you suggested is by no means scientific, and you acknowledged that first. -- 325xi 325xi's Profile: http://forums.slimdevices.com/member.php?userid=5661 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
325xi;184327 Wrote: ...I'm interested to find out the limit of jitter control of LED-plastic toslink vs. coax - please note - regardless of its audibility And of course I accept scientific basis. I don't believe in listening tests unless arranged in a proper way. The test you suggested is by no means scientific, and you acknowledged that first. AHA!!! I think we got hung up on language here then. Thank you for the clarification. If I misunderstood your position I think it was due to the language getting used in this discussion and its relationship to Audiophile beliefs - you did the post on the Wiki page so perhaps you understand what I mean here. When people say around here they don't believe in listening tests, it generally means they do not accept the scientific study of audibility and the engineering associated to that or that their principles are very different than the objectivist crowd. So, let me see if understand your question. If we took a signal, and split it to run through a S/PDIF standard LED and plastic fibre, and put the same signal through a 75ohm coax link, then looked at the receiver end and measured one standard deviation of jitter, which would be smaller? -- Eric Carroll Transporter-Bryston 3B SST-Paradigm Reference Studio 60 v.4 SB3-Rotel RB890-BW Matrix 805 SB3-Pioneer VSX-49TXi-Mirage OM7+C2+R2 ReadyNAS NV+ Eric Carroll's Profile: http://forums.slimdevices.com/member.php?userid=9293 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Optical connection - inferior by default?
Eric Carroll;184333 Wrote: AHA!!! I think we got hung up on language here then. Thank you for the clarification. If I misunderstood your position I think it was due to the language getting used in this discussion and its relationship to Audiophile beliefs - you did the post on the Wiki page so perhaps you understand what I mean here. When people say around here they don't believe in listening tests, it generally means they do not accept the scientific study of audibility and the engineering associated to that or that their principles are very different than the objectivist crowd. So, let me see if understand your question. If we took a signal, and split it to run through a S/PDIF standard LED and plastic fibre, and put the same signal through a 75ohm coax link, then looked at the receiver end and measured one standard deviation of jitter, which would be smaller? Now look, you know full well that cable-induced jitter is related to the length of the cable and this is different for coax and toslink...so how are you going to compare apples with apples? -- Phil Leigh Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
