SwissBear Posted September 16, 2017 Share Posted September 16, 2017 8 hours ago, Confused said: Ultimately it goes back to needing a few more 'data points' before this makes more sense or at least we can discern some clear trends. I would suggest these data points include the tx-USB Ultra into the chain. I had the opportunity to listen to the tx-USB Ultra together with the sMS-200 Ultra I already have in the chain this afternoon and this is another significant step forward in terms of transparency. This tx-USB Ultra is, IMHO, a much more pertinent clue to our difference of perception than the cables. So better a Trifecta than an sMS-200 Ultra. Don't understand why, apart from charging more, they didn't package them together Link to comment
SwissBear Posted September 16, 2017 Share Posted September 16, 2017 1 hour ago, rickca said: @julian.david is it not possible for Mutec to significantly improve the performance of the MC-3+ Smart Clock USB to yield something more cost effective than the REF 10 Masterclock? Good idea ! Actually I had the same thought. Packaging the good LPSU of the Ref-10, a down-scaled Ref-10 with only one or two clock outputs, and one or two MC-3+ USB into one single box would be awesome. Would save some cable and allow for a 1st class reclocker all-in-one Link to comment
austinpop Posted September 16, 2017 Share Posted September 16, 2017 4 minutes ago, SwissBear said: I would suggest these data points include the tx-USB Ultra into the chain. I had the opportunity to listen to the tx-USB Ultra together with the sMS-200 Ultra I have already in the chain this afternoon and this is another significant step forward in terms of transparency. This tx-USB Ultra is, IMHO, a much more pertinent clue to our difference of perception than the cables. So better a Trifecta than an sMS-200 Ultra. Don't understand why, apart from charging more, they didn't package them together Wow, the plot thickens! So your chain was: trifecta (modded switch+sMS-200ultra+tX-USBultra) > Mutec MC-3+ USB > Devialet DAC (using AES)? Ref 10 feeding 10 MHz to sMS, tX, and MC-3+ USB? As to why SOtM didn't package them together. Well ... the trifecta was not their brainchild. In fact, it was a discovery based on a conjecture (not even a theory) of @romaz's - as he explained over on the other thread! His findings were soon confirmed by me and many others. Indeed, his first mods predated the existence of the Ultra gear - he essentially had them graft an sCLK-EX board into their existing DDC, the dX-USB HD. I don't think even SOtM expected the SQ benefits we derived! The Utra line came after those findings. After the fact - now - I do believe they offer bundles, at least through their US distributor Crux. I am sure our findings here and on the other thread have not gone unnoticed by the Mutec's, the SOtM's, the Uptone's and the Sonore's, and others of the world. I am sure none of us want these absurd chains of devices, other than the result sounds so damn good! In my mind, the race is on for a singular device that combines the goodness of the trifecta, DDCs like the MC-3+ and the SU-1, master reference clocks like the Ref 10, and PSUs like LPS-1 and the SR7. If I could get a single box at a fair price that did all that, while giving me the flexibility to attach an external PSU and reference clock, I would gladly replace my so-called "clock chain" with it. It's a fantastic time to be a computer audiophile! julian.david 1 My Audio Setup Link to comment
k-man Posted September 16, 2017 Share Posted September 16, 2017 2 hours ago, rickca said: @julian.david is it not possible for Mutec to significantly improve the performance of the MC-3+ Smart Clock USB to yield something more cost effective than the REF 10 Masterclock? I also hope to see something better at a price point somewhere in between the MC3+ and REF 10. Link to comment
mourip Posted September 16, 2017 Share Posted September 16, 2017 I would be interested in a comparison between the REF10 and the Cybershaft 10MHz OCXO premium master clock. $3k vs ~$800 usd To be fair the Cybershaft only has one BNC output. "Don't Believe Everything You Think" System Link to comment
romaz Posted September 16, 2017 Share Posted September 16, 2017 On 9/11/2017 at 1:44 PM, barrows said: The DS DAC from PS Audio always operates in master mode for its converter section, as it is an asynchronous DAC by design, that is it resamples all incoming data asynchronously to its single internal masterclock. This does not matter what input you use. Here is John Swenson's response to asynch USB DACs: "But what about asynch USB, isn't the DAC in control? Overall yes, the DAC has its OWN FIFO and also checks it, but instead of changing a clock frequency it sends a command back to the computer which tells it to speed up or slow down the average sample rate. So even though the local DAC clock is in ultimate control of the sample rate, as far as the MC3+/USB is concerned the USB data stream is in control, it just passes it on down to the DAC." Link to comment
austinpop Posted September 16, 2017 Share Posted September 16, 2017 28 minutes ago, mourip said: I would be interested in a comparison between the REF10 and the Cybershaft 10MHz OCXO premium master clock. $3k vs ~$800 usd To be fair the Cybershaft only has one BNC output. Coincidentally, I just received a Cybershaft OP-14 in the house that is burning in. I will be trying it on my trifecta, and reporting on the novel thread. I would love to do the comparison you suggested, but sadly, I don't live in the Utopian world of @SwissBear and @zoltan, where local dealers come by with loaner Ref 10s, and presumably, frankincense and myrrh. This is 'Murica. That's not how we roll. My Audio Setup Link to comment
austinpop Posted September 16, 2017 Share Posted September 16, 2017 12 minutes ago, romaz said: Here is John Swenson's response to asynch USB DACs: "But what about asynch USB, isn't the DAC in control? Overall yes, the DAC has its OWN FIFO and also checks it, but instead of changing a clock frequency it sends a command back to the computer which tells it to speed up or slow down the average sample rate. So even though the local DAC clock is in ultimate control of the sample rate, as far as the MC3+/USB is concerned the USB data stream is in control, it just passes it on down to the DAC." Thanks Roy. I try to remind folks of this every chance I get. Asynchronous USB only means the receiver controls the average sample rate. The data is still clocked by the source. That is why reclockers/regenerators upstream can still impact the SQ of async USB. simonklp 1 My Audio Setup Link to comment
Popular Post romaz Posted September 17, 2017 Popular Post Share Posted September 17, 2017 I'm back from my travels for now. I also just a few days ago received my gear back from SOtM. I have gone a bit crazy with my build, more than I really needed to but I wanted to answer for myself certain questions about what matters and what doesn't with respect to all this clocking. While I will need more time to draw my definitive conclusions, here is what I can say for now. Back in Munich, I was quite enamored with how the REF10 elevated the SQ of Mutec's very fine MC-3+USB, enough so that I bought the REF10. While I fully believed the REF10 would elevate SOtM's products, I didn't know to what extent and so this was a bit of a gamble. I would have to agree with SwissBear that the REF10's impact on individual Ultra components from SOtM is less prominent when compared against what I heard with the MC-3+USB. Is this because the sCLK-EX's stock internal clock is better than the stock clock in the MC-3+USB? I'm not sure but if someone is going to buy a REF10 for something like the sMS-200ultra and stop there, I'm not sure I would consider a REF10 purchase worthwhile. Where the REF10 earns its keep (and boy, does it earn it) is when its abilities are applied en masse. From one component to the next, I have noticed a variable impact but as you add them together, it becomes an "OMG" moment. As of now, here are the 8 clocks I have replaced using 2 SOtM's sCLK-EX clock boards: 1. Netgear C3000 cable modem/router/switch - 2 clocks. There are more powerful devices like this out there with a richer feature set but I specifically chose this model because it uses low power components. While this device has Wi-FI capability, I don't use it. I use a separate device in a separate room as my Wi-Fi access point for my home and so this device only serves as an internet modem, simple router and 2-port switch. It only draws 1.5A at 12V and so it was my feeling that this would result in better SQ. When I compared it against my much more powerful Netgear Nighthawk Wi-Fi router which draws up to 3.5A, with each powered by their stock SMPS, I found slightly better SQ with this low power C3000. Powering either with a 12V lead from my Paul Hynes SR7 predictably improved SQ but again, I felt SQ was slightly better from the low power C3000. As such, I sent this unit to SOtM and they replaced its 2 clocks and added capacitors. The switching regulators could not be replaced due to excessive heat concerns. 2. DFI BW171 motherboard - 1 clock. This is a mini-ITX motherboard with an embedded Celeron that consumes no more than 8 watts. It is passively cooled, has a very small electrical footprint and when powered by my SR7, SQ was superior to my modified Mac Mini which was also powered by my SR7. This board's 25MHz system clock was replaced. This system clock then serves as a reference clock for many "subclocks" embedded within the motherboard and many of these clocks are not replaceable but there are ways around this. For example, the USB clock on this motherboard can't be replaced although if you use a PCIe USB card, the clock on that card can be replaced. 3. Intel i211AT 2-port LAN board - 1 clock. Because of lack of available PCIe slots, I chose to use the motheboard's integrated LAN board. Each of the 2 ports has its own clock that is replaceable but because these clocks are identical, I was able to use a single clock from the sCLK-EX board to provide clocking to both ports. If I was outputting to an Ethernet endpoint such as an sMS-200ultra or ultraRendu, I probably would have opted for a dedicated PCIe Ethernet card where capacitors can be added and the switching regulators replaced. 4. SOtM tX-USBhubIN - 1 clock. This internal USB clock board is the same board used in the tX-USBultra. Many will be surprised to know that I chose this card not as an output card but as an input card. Many who have followed my build on the other thread know that I noted a nice bump in SQ when I connected my music data drive to an Adnaco fiber USB card instead of one of the motherboard's stock USB ports. With further testing, I found a further bump in SQ with this card over the Adnaco and so this card is used to connect my array of Lexar 512GB compact flash cards for music storage (presently 2TB worth of storage). I have found this solution easily superior to anything I have tried thus far, either direct storage or NAS. 5. SOtM tX-USBexp USB card - 1 clock. This is SOtM's PCIe-based USB card. If I had another available PCIe slot, I would have bought 2 of these instead of the tX-USBhubIN card because according to Lee, SOtM's lead engineer, this card is his finest product. Of interest, while at Munich, he described his sMS-200ultra and tX-USBultra as his "mid-level" products. He suggested his very best product is his sMS-1000SQ and a large reason for this is because of this card. While similar in many ways, the USB chipset, regulator circuitry and the filtration built into this card are his very best. He said with this card in "Ultra" form, there should be no need for an sMS-200ultra. As an owner of an sMS-200ultra, I would have to agree. 6. ISO-Regen - 1 clock. I have to agree with SwissBear, this very fine device is a step down compared to the tX-USBultra with regards to resolution and while I like how it improved the tonal density of my slightly thin SOtM setup, the perceived compromise in resolution made it a "no-go" for me -- unless of course I could replace its clock and so that is what I have done. First off, SOtM will not replace the clock on any ISO-Regens. While they have great respect for Uptone Audio, they feel this device is too close a competitor. Feel free to ask them but don't be surprised if they politely tell you "no." With that said, there are many out there with the skill set to replace the 25MHz clock on the ISO-Regen for those so inclined. Is this modified ISO-Regen now at the level of the tX-USBultra? Not quite. I still prefer the tX-USBultra as my final endpoint before my DAC but the improvement is undeniable. 7. tX-USBultra - 1 clock. This unit served as the host for my 2nd sCLK-EX board and is the endpoint that connects directly to my DAC. What the above setup allows me is that from the beginning of my digital chain up to my Chord Blu Mk2 / DAVE, every bad clock that I can replace has now been replaced to the level of the REF10's OCXO. With the exception of my OS drive and my compact flash USB hubs that I use for storage, everything is powered by independent rails from several Paul Hynes SR7s. What I am saying is that both clocking and power delivery are of an equivalent standard from beginning to end. Now, Chord DAVE is an asynchronous USB DAC and in fact, this is its best input. Rob Watts implemented a floating USB design that provides very effective galvanic isolation to the extent that an Intona made no positive difference. Even the galvanic isolation offered by the ISO Regen results in minimal impact. Chord's new Blu Mk 2 with built-in M-scaler has now been added to my chain and what this effectively does is it increases DAVE's TAP resolution 6-fold to the extent where DAVE now has a TAP-length filter in excess of 1-million TAPS. This device also incorporates galvanic isolation and paired with DAVE, it was assumed by many including Rob Watts that all of my tinkering would have much less impact, if any at all. Despite the gigantic impact of the M-scaler in Blu Mk 2 to my Chord DAVE, my server build with all clocks replaced seems to be making an even larger impact than before. No matter how good a DAC, no matter how many defenses it implements to ward off RF and jitter, it would appear to me that there are huge gains to be had by paying attention to your digital front end. While the REF10s impact on any individual component ranges from small to large, its collective impact on my whole chain cannot be adequately expressed in words because as of now, I have never heard a system quite like this with respect to smoothness, resolution, transparency and dynamics. These are traits generally reserved for analog devices like amplifiers and speakers and so to make this claim with digital gear before the DAC is really quite a statement. Like many of you, I value simplicity whenever I can get it which is one of the reasons I went away from Ethernet endpoints like the sMS-200ultra. As a minimum, I know I could be very happy using a single sCLK-EX board (and its 4 clocks) and forgo reclocking the modem/router/switch, Iso-Regen and tX-USBultra. This means that with a single box server with integrated sCLK-EX board, a 4-rail SR7, and a REF10, I would feel I was in end-game territory but I will say that adding the reclocked modem/router/switch, ISO-Regen and tX-USBultra definitely improves things further. Lastly, with regards to clock cables, I have explored this to some extent although I have a few other clock cables coming in. With the Habst cables against a 0.5m Pasternack RG-59 (about $40) and a 0.5m Blue Jeans Cables RG-6 with Canare BNCs ($17), there's no contest, unfortunately. With these lesser cables, there is an obvious HF glare that is present. I can get used to it and things can sound pretty good but as soon as I swap in the Habst, the improvement in detail clarity and the disappearance of this glare is very apparent. If someone is contemplating an inexpensive clock cable, I would suggest the less expensive Blue Jeans Cables over the Pasternack. Whether this is because RG-6 is better shielded and has less signal attenuation then RG-59, it's hard to say but one seems to sound a little better than the other although the difference is small. Next week, I have a Black Cat Silver Star 75 coming in. It is supposed to play in the league of the big boys at a more affordable price point of $250 and so we'll see. johndoe21ro, austinpop, Confused and 5 others 4 1 3 Link to comment
mozes Posted September 17, 2017 Share Posted September 17, 2017 56 minutes ago, romaz said: adding the reclocked modem/router/switch, ISO-Regen and tX-USBultra definitely improves things further. I suppose reclocking these components is only to improve streaming e.g Tidal or from a NAS. Link to comment
barrows Posted September 17, 2017 Share Posted September 17, 2017 2 hours ago, romaz said: Here is John Swenson's response to asynch USB DACs: "But what about asynch USB, isn't the DAC in control? Overall yes, the DAC has its OWN FIFO and also checks it, but instead of changing a clock frequency it sends a command back to the computer which tells it to speed up or slow down the average sample rate. So even though the local DAC clock is in ultimate control of the sample rate, as far as the MC3+/USB is concerned the USB data stream is in control, it just passes it on down to the DAC." RE the PS Audio DS, I was not referring to its USB input in this case, which is of course async as are all commonly used USB inputs. I was actually referring to operation of the rest of the DAC after the USB input . The I2S feed comes from wherever (any of the inputs) and is then oversampled into an entirely new clock domain controlled by a separate masterclock oscillator. The masterclock in the Directstream is the only clock which has any involvement in what happens after that. SO/ROON/HQPe: DSD 512-Sonore opticalModuleDeluxe-Signature Rendu optical with Well Tempered Clock--DIY DSC-2 DAC with SC Pure Clock--DIY Purifi Amplifier-Focus Audio FS888 speakers-JL E 112 sub-Nordost Tyr USB, DIY EventHorizon AC cables, Iconoclast XLR & speaker cables, Synergistic Purple Fuses, Spacetime system clarifiers. ISOAcoustics Oreas footers. SONORE computer audio | opticalRendu | ultraRendu | microRendu | Signature Rendu SE | Accessories | Software | Link to comment
barrows Posted September 17, 2017 Share Posted September 17, 2017 2 hours ago, austinpop said: Asynchronous USB only means the receiver controls the average sample rate. The data is still clocked by the source. This is factually inaccurate. Asynchronous USB does the following: Data stream coming in is buffered and the buffer is controlled by software, the software sends commands upstream to the serving device only to manage the buffer such that it does not get too full or too empty. This is done so that there are always samples available to the output. The output of the buffer is directly clocked by a free running oscillator, and the only thing which determines the timing of the samples is the accuracy of this oscillator: output jitter has no relation to anything going on further upstream (except perhaps due to low level noise effects affecting the local clocks jitter). d_elm 1 SO/ROON/HQPe: DSD 512-Sonore opticalModuleDeluxe-Signature Rendu optical with Well Tempered Clock--DIY DSC-2 DAC with SC Pure Clock--DIY Purifi Amplifier-Focus Audio FS888 speakers-JL E 112 sub-Nordost Tyr USB, DIY EventHorizon AC cables, Iconoclast XLR & speaker cables, Synergistic Purple Fuses, Spacetime system clarifiers. ISOAcoustics Oreas footers. SONORE computer audio | opticalRendu | ultraRendu | microRendu | Signature Rendu SE | Accessories | Software | Link to comment
simonklp Posted September 17, 2017 Share Posted September 17, 2017 2 hours ago, austinpop said: Thanks Roy. I try to remind folks of this every chance I get. Asynchronous USB only means the receiver controls the average sample rate. The data is still clocked by the source. That is why reclockers/regenerators upstream can still impact the SQ of async USB. Thank you @austinpop for your valuable information. This is the answer that I want for the question that I had asked about "why music playback by asynchronous USB process is still affected by accuracy of the clocks in the chain at upstream of the DAC" in several weeks ago. At that time, instead of not getting this answer, I got a feeling in some of the subsequent discussion that people was always challenging the observations in this thread. After all, I would like to point out that progress in many aspects (e.g. science & etc.) is made by questioning, making hypothesis, conducting experiments, observation, drawing conclusions and etc. By reiterating this process, human beings have achieved the advancement in these many aspects nowadays. Thanks again to @austinpop for your valuable information. Wish you a nice weekend. Cheers. Link to comment
barrows Posted September 17, 2017 Share Posted September 17, 2017 5 minutes ago, simonklp said: Thank you @austinpop for your valuable information. This is the answer that I want for the question that I had asked about "why music playback by asynchronous USB process is still affected by accuracy of the clocks in the chain at upstream of the DAC" in several weeks ago. At that time, instead of not getting this answer, I got a feeling in some of the subsequent discussion that people was always challenging the observations in this thread. After all, I would like to point out that progress in many aspects (e.g. science & etc.) is made by questioning, making hypothesis, conducting experiments, observation, drawing conclusions and etc. By reiterating this process, human beings have achieved the advancement in these many aspects nowadays. Thanks again to @austinpop for your valuable information. Wish you a nice weekend. Cheers. That information is inaccurate. This is not how async USB works. Just because something is the answer you "wanted" does not actually change how async USB receivers work. simonklp 1 SO/ROON/HQPe: DSD 512-Sonore opticalModuleDeluxe-Signature Rendu optical with Well Tempered Clock--DIY DSC-2 DAC with SC Pure Clock--DIY Purifi Amplifier-Focus Audio FS888 speakers-JL E 112 sub-Nordost Tyr USB, DIY EventHorizon AC cables, Iconoclast XLR & speaker cables, Synergistic Purple Fuses, Spacetime system clarifiers. ISOAcoustics Oreas footers. SONORE computer audio | opticalRendu | ultraRendu | microRendu | Signature Rendu SE | Accessories | Software | Link to comment
simonklp Posted September 17, 2017 Share Posted September 17, 2017 Just now, barrows said: That information is inaccurate. This is not how async USB works. @barrows Ok. Fair enough. I welcome open minded discussion of counter theory. Again, as I said that through questioning (or proposing counter theory), making hypothesis, conducting experiments, observation, drawing conclusions and etc, progress in the computer audiophile technologies and many other aspects can be made. After all, we are in the 21st century now. Wish you a great weekend. Cheers. Link to comment
pkane2001 Posted September 17, 2017 Share Posted September 17, 2017 2 minutes ago, simonklp said: @barrows Ok. Fair enough. I welcome open minded discussion of counter theory. Again, as I said that through questioning (or proposing counter theory), making hypothesis, conducting experiments, observation, drawing conclusions and etc, progress in the computer audiophile technologies and many other aspects can be made. After all, we are in the 21st century now. Wish you a great weekend. Cheers. Just remember that a counter theory is only applicable to things that can be reasonably questioned. How isochronous USB protocol works is not one of those. A counter theory or a new hypothesis are not needed since there is a very clear and detailed documented definition. There is no doubt as to how it works, and @barrowsdescribed the function correctly. Now, noise in the USB transmission and receiver is another matter and that is subject to (frequent) speculation and debates. simonklp 1 -Paul DeltaWave, DISTORT, Earful, PKHarmonic, new: Multitone Analyzer Link to comment
barrows Posted September 17, 2017 Share Posted September 17, 2017 15 minutes ago, simonklp said: @barrows Ok. Fair enough. I welcome open minded discussion of counter theory. How async USB audio actually works is not a "theory". simonklp 1 SO/ROON/HQPe: DSD 512-Sonore opticalModuleDeluxe-Signature Rendu optical with Well Tempered Clock--DIY DSC-2 DAC with SC Pure Clock--DIY Purifi Amplifier-Focus Audio FS888 speakers-JL E 112 sub-Nordost Tyr USB, DIY EventHorizon AC cables, Iconoclast XLR & speaker cables, Synergistic Purple Fuses, Spacetime system clarifiers. ISOAcoustics Oreas footers. SONORE computer audio | opticalRendu | ultraRendu | microRendu | Signature Rendu SE | Accessories | Software | Link to comment
simonklp Posted September 17, 2017 Share Posted September 17, 2017 42 minutes ago, pkane2001 said: Just remember that a counter theory is only applicable to things that can be reasonably questioned. How isochronous USB protocol works is not one of those. A counter theory or a new hypothesis are not needed since there is a very clear and detailed documented definition. There is no doubt as to how it works, and @barrowsdescribed the function correctly. Now, noise in the USB transmission and receiver is another matter and that is subject to (frequent) speculation and debates. Ok, fair enough too. Also thank you for your valuable information. I think even though your information is the fact, if other people have observations that appears to be in conflict with this, it is fine for any volunteer to propose new theory (not necessarily conflicting to the previous "fact") in an attempt to find out somethings that may be overlooked and/or etc., such as hypothesis in the area of "noise in the USB transmission and reception" that you have just mentioned. The process mentioned by me earlier still applies except that it may start with observation and then questioning, making hypothesis, conducting experiments, … and etc., i.e. change in the process sequence only. I think that this kind of situation had also happened in many aspects before, which includes the scientific or technological exploration fields. Again, after all, we are in the 21st century. It is a nice to treasure the experience sharing and objective questioning from others. Wish you a nice weekend too. Cheers. Link to comment
simonklp Posted September 17, 2017 Share Posted September 17, 2017 35 minutes ago, barrows said: How async USB audio actually works is not a "theory". Ok, noted with thanks. Cheers. Link to comment
barrows Posted September 17, 2017 Share Posted September 17, 2017 38 minutes ago, simonklp said: Ok, noted with thanks. Cheers. The reason i am so adamant in my reponses is because it does a disservice to the community to suggest "theories" which are factually incorrect. As I mentioned in my first response, the influence of noise coming over USB may be able to reduce clock performance in the USB receiver/DAC influencing jitter caused artifacts in the DACs analog output, hence the great lengths we go to with Sonore Rendu products to reduce that noise. I have no doubt that USB source qualities can influence the overall outcome of system performance, but the important point here is that the clocking of Async USB is not reliant on the upstream clocks, the only clocks which matter (for this) are those which clock out the I2S feed from the USB interface buffer. The upstream clock(s) appear to exert what I would term a second order effect which may effect DAC output quality, but the important distinction is that this effect is not directly related to how the I2S data is clocked out of the USB interface. This is why Sonore uses a "femto" clock in the ultra and Signature Rendu products. The only plausible explanation for this second order effect is noise coming over the USB input, causing some disruption in the DAC (ground bounce, etc). simonklp 1 SO/ROON/HQPe: DSD 512-Sonore opticalModuleDeluxe-Signature Rendu optical with Well Tempered Clock--DIY DSC-2 DAC with SC Pure Clock--DIY Purifi Amplifier-Focus Audio FS888 speakers-JL E 112 sub-Nordost Tyr USB, DIY EventHorizon AC cables, Iconoclast XLR & speaker cables, Synergistic Purple Fuses, Spacetime system clarifiers. ISOAcoustics Oreas footers. SONORE computer audio | opticalRendu | ultraRendu | microRendu | Signature Rendu SE | Accessories | Software | Link to comment
simonklp Posted September 17, 2017 Share Posted September 17, 2017 45 minutes ago, barrows said: The reason i am so adamant in my reposes is because it does a disservice to the community to suggest "theories" which are factually incorrect. As I mentioned in my first response, the influence of noise coming over USB may be able to reduce clock performance in the USB receiver/DAC influencing jitter caused artifacts in the DACs analog output, hence the great lengths we go to with Sonore Rendu products to reduce that noise. I have no doubt that USB source qualities can influence the overall outcome of system performance, but the important point here is that the clocking of Async USB is not reliant on the upstream clocks, the only clocks which matter (for this) are those which clock out the I2S feed from the USB interface buffer. The upstream clock(s) appear to exert what I would term a second order effect which may effect DAC output quality, but the important distinction is that this effect is not directly related to how the I2S data is clocked out of the USB interface. This is why Sonore uses a "femto" clock in the ultra and Signature Rendu products. The only plausible explanation for this second order effect is noise coming over the USB input, causing some disruption in the DAC (ground bounce, etc). @barrows Thank you very much for your valuable information. This is what I treasure to have discussion or sharing accompanied with so much new information to me. There are always new things for me to learn in the CAS technology. That's the reason I always browses through this forum to understand more. So, do you mean that the plausible explanation to the effect of upstream clocks is due to their lower noise instead of their higher timing accuracy? Am I understand it correctly? Thank you again for your valuable information. Cheers. Link to comment
barrows Posted September 17, 2017 Share Posted September 17, 2017 9 minutes ago, simonklp said: So, do you mean that the plausible explanation to the effect of upstream clocks is due to their lower noise instead of their lower timing accuracy? Am I understand it correctly? The only plausible explanation is that the result of a better clock in the upstream digital USB source (say an ultra Rendu) is that the improved timing reduces noise on the USB feed to the DAC. I will not rule out the possibility that there might be some other advantage to a better clock in this position, but at this time it appears to be extremely unlikely, to the point of being virtually absurd. Note the same does not apply to digital sources where one is using a SPDIF output, that is an entirely different thing, I am referring to USB output devices here. As this is the mutec clock thread, i would also suggest that it is crazy to use such a high quality clock on (like an SMS-200 ultra) a USB output device unless first the actual DAC clock has been brought up to at least the same low level of phase noise. Upgrading the DAC clock is going to offer an exponentially better improvement than upgrading the clock in a USB source device ( or router, switch etc). For the price of the Mutec, one could get a competent tech/modder to put a really awesome clock(s) upgrade in their DAC for a much larger performance increase. simonklp 1 SO/ROON/HQPe: DSD 512-Sonore opticalModuleDeluxe-Signature Rendu optical with Well Tempered Clock--DIY DSC-2 DAC with SC Pure Clock--DIY Purifi Amplifier-Focus Audio FS888 speakers-JL E 112 sub-Nordost Tyr USB, DIY EventHorizon AC cables, Iconoclast XLR & speaker cables, Synergistic Purple Fuses, Spacetime system clarifiers. ISOAcoustics Oreas footers. SONORE computer audio | opticalRendu | ultraRendu | microRendu | Signature Rendu SE | Accessories | Software | Link to comment
simonklp Posted September 17, 2017 Share Posted September 17, 2017 2 minutes ago, barrows said: The only plausible explanation is that the result of a better clock in the upstream digital USB source (say an ultra Rendu) is that the improved timing reduces noise on the USB feed to the DAC. I will not rule out the possibility that there might be some other advantage to a better clock in this position, but at this time it appears to be extremely unlikely, to the point of being virtually absurd. Note the same does not apply to digital sources where one is using a SPDIF output, that is an entirely different thing, I am referring to USB output devices here. As this is the mutec clock thread, i would also suggest that it is crazy to use such a high quality clock on (like an SMS-200 ultra) a USB output device unless first the actual DAC clock has been brought up to at least the same low level of phase noise. Upgrading the DAC clock is going to offer an exponentially better improvement than upgrading the clock in a USB source device ( or router, switch etc). For the price of the Mutec, one could get a competent tech/modder to put a really awesome clock(s) upgrade in their DAC for a much larger performance increase. @barrowsThank you again for your valuable advice. In fact, this is actually the discussion or information that I would like to get. I had made an incorrect statement in my earlier message in this thread about 2 hours ago. In fact, my question about "why music playback by asynchronous USB process is still affected by accuracy of the clocks in the chain at upstream of the DAC" in several weeks ago was made in another thread namely "A novel way to massively improve the SQ …". At that time, I stated statements in that thread, which is listed as follows: - QUOTED "I had doubt that whether this kind of improvement by using a better clock (e.g. sCLK-EX) only applies to cases where the Asynchronous USB Transfer mode is not properly implemented. Because under this transfer mode, the clock of the DAC is the master that the clocks of the upstream devices should not really affect so much. For example, in case of playback using HQPlayer with NAA, the NAA isolates as much as possible at the software side by using a large asynchronous FIFO buffer. Is there really a substantial improvement by replacing the original clocks by better ones at the upstream side of DAC? Was there any experiment on this case? Thank you for your kind advice in advance." UNQUOTED At that time, neither did I get related advice nor the related information. Instead, there was comment in the thread criticising people of their act to question the observation of others. It was not a good experience to me. That's the reason why I always say that I always treasure contradicting information, questioning, sharing experience and information and etc. so that progress maybe made. In any case, it's good to communicate with you and learn more from you. Thank you again for your kind advice and sharing. Cheers. barrows 1 Link to comment
austinpop Posted September 17, 2017 Share Posted September 17, 2017 4 hours ago, romaz said: No matter how good a DAC, no matter how many defenses it implements to ward off RF and jitter, it would appear to me that there are huge gains to be had by paying attention to your digital front end. Roy, Thanks for another invaluable post. Your sentence above perfectly represents my experience too. My Audio Setup Link to comment
Popular Post austinpop Posted September 17, 2017 Popular Post Share Posted September 17, 2017 4 hours ago, barrows said: This is factually inaccurate. Asynchronous USB does the following: Data stream coming in is buffered and the buffer is controlled by software, the software sends commands upstream to the serving device only to manage the buffer such that it does not get too full or too empty. This is done so that there are always samples available to the output. The output of the buffer is directly clocked by a free running oscillator, and the only thing which determines the timing of the samples is the accuracy of this oscillator: output jitter has no relation to anything going on further upstream (except perhaps due to low level noise effects affecting the local clocks jitter). You are correct about what happens in a typical DAC, but I was referring to the incoming data stream from the source, which is still clocked by the source. The reason for my statement was that there is a pervasive, yet incorrect, impression out there that in "asynchronous USB," the target supplies the clock for the data flowing from source to target. In fact, as John mentioned, the target only uses an explicit feedback mechanism, effectively a flow control mechanism. Both source and target have free running clocks. Here's a nice simple explanation paper: https://www.silabs.com/documents/public/white-papers/usb-audio-simplified.pdf What Roy, I, and others have found is that improving the source clock in an asynchronous USB transfer yields incredible improvements in SQ. This, despite the fact that many/most DACs have buffers after their USB input stages from which they reclock the data, not to mention all sorts of sophisticated schemes for galvanic isolation, jitter reduction, and what not. I don't pretend to know why such profound SQ improvements happen, even though on face value, the buffering and reclocking within the DAC should render upstream effects irrelevant. But empirically, we are finding these SQ improvements are very real. Clearly, there is more to be learned. Even with a $20k+ combo of Chord Blu M-Scaler/DAVE, Roy still found the upstream clock improvements to profoundly matter. I don't want to go off on the weeds with this, given that this is a Mutec Ref 10 thread. I will stipulate I am not a USB audio engineer, so my explanation was in laymen's terms. romaz and auricgoldfinger 2 My Audio Setup Link to comment
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