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ecwl

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About ecwl

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  1. Wow. I can’t believe this PSU thing is generating so much controversy. I don’t own a Qutest. Half the time, when Rob Watts writes something on Head-Fi, I don’t really understand what he’s saying. Takes re-reading it several times and thinking about it to understand a little more. Moreover, he changes his mind over time. Or he would say, he was expecting other people to use better source components or pre-amp/amp so the problem is not with Chord products/supplied PSUs but he acknowledges that a problem can exist. Going to Head-Fi and reading Rob Watts thoughts, the following is what I got even though I understood like 30% of what he’s saying: there is no ground with the supplied Qutest PSU; and that is done on purpose, as it eliminates the possibility of ground loops.for sure ground loops are the major issue, as it's a low impedance direct connection. The problem with a non ground connected PSU is much smaller again, as it is capacitively coupled to the mains and then to ground via the PSU transformer; so here we have the possibility of another loop; but it's capacitive, so only applies with RF signals, not leakage currents in the audio bandwidth. Clearly having as low as possible mains coupling capacitance will be good; so we need a PSU that has a low interwinding transformer capacitance - and guess what, the lowest capacitance are found on those awful SMPS - those pesky small mickey mouse things that audiophiles think are poor.Also - the capacitive problem only applies at RF, and guess what - you can use RF filters to further isolate the effects of the coupling capacitance - I have proven this via SPICE modelling, an RF PSU filter can be made to isolate the capacitive coupling to ensure that the mains loop is broken - no RF current can flow via this loop. and Qutest is full of RF filters to isolate the RF and capacitive coupling from the mains.To get rid of RF you must have effective RF filtering, and that means a complex multistage filter. But even simple SMPS filters are better than no filters that are often in linear PSU's.The hard bright sound is characteristic of more random RF noise entering your system, creating more noise floor modulation, which makes it sound brighter, and if bad, harder and grainy. But if you are worried about the mains loop then a simple way is to use a USB battery power pack. That will completely eliminate the issue, as it's totally isolated from the mains. My own listening tests revealed tiny differences by replacing the Qutest PSU with a battery - but that was with my setup so YMMV. The one I use is Poweradd Pilot Pro2. Now this has internal regulators - so it is noisy on the OP - but the key is the absence of mains bourne RF noise. With Hugo 2, adding the unit makes no difference to the SQ, and it's the issue of RF noise that is key, not the noise on the OP. Also, it's completely isolated from the mains, so no ground loops or leakage current is possible. Like I said, I don’t even fully understand most of this. And in other posts, Rob Watts has acknowledged that in some systems, the high-impedance leakage current ground loop noise can play a role in the sound. So my take is that obviously, with a linear power supply for Qutest, you’re going to get less high-impedance leakage current ground loop noise in your system if it’s in other components’ PSUs. So you might like the sound more with LPSU and Qutest in your system because of this. Alternatively, you might just like more RF from the LPSU creating a brighter sound. Or as some have said, there are LPSUs and then there are really good LPSUs that might actually address Rob Watts’ concerns. It would be great if someone with more expertise on LPSUs actually address Rob Watts’ comments instead of a blanket “battery better” or “LPSU better“ or “stock SMPS better”. Otherwise, it just sounds like we are just cheering for our favourite sports teams (not that there is anything wrong with that, I guess).
  2. I totally agree. Moreover, I’m sure Rob Watts only tested power supplies that would be reasonable to include in a product that’s Qutest price range. Like he’s not going to test a power supply that costs 25% of Qutest MSRP. On the flip side, the challenge for all of us is that if there’s an alternative power supply that costs 10-25% of Qutest, there’s no guarantee that it performs better than the stock switching power supply. And even if the pricier power supply outperforms the stock switching supply in some characteristics, the internal power filtering of the Qutest is probably optimized for the stock power supply. So let’s say the stock power supply has more non-RF noise and less RF noise and the Qutest internally filters out the non-RF noise, you can potentially get a pricy power supply that has no non-RF noise but more RF noise so Qutest could perform worse. I don’t really understand the details of how Qutest filters the power from the stock power supply but according to Rob Watts, it’s quite extensively. Ultimately, I think people interested in trying other power supplies should do what they want and see if it sounds better as long as they don’t accidentally blow their DAC with the wrong voltage.
  3. I think Rob Watts has said on Head-Fi on a number of occasions that if you change the power supply and you think the music sounds better but also slightly brighter, he believes it’s because there is more RF from the power supply, causing more noise floor modulation which seems to give more detail. Specifically referring to the Hugo TT2 and M-Scaler switching power supply (but Qutest has a different one), Rob Watts has also said that he chose that supply because it has the best measured and sound quality performance, measuring similar to battery power supply, even though there is a 100uA leakage current to ground in that power supply. He acknowledges that if the upstream devices have leakage ground currents, then it would affect the performance of Qutest but he really thinks that’s the problem of the streamer and not of his DAC power supply. Moreover, he also fully acknowledges the possibility that the switching power supply could affect the performance of your amplifier but he sees the issue as the amplifier being sensitive, rather than a DAC design issue. He also thinks the problem is rare because most amplifiers are well-designed. While I really admire Chord DACs, I’m a bit less dogmatic about the power supply. My take is that for most people, if they want to hear their DAC as the designer intended, just connect the DAC to a battery-powered USB source or via Toslink to stop the ground noise. However, I am aware that there are battery-powered USB sources (usually very old laptops) that are so noisy that Chord DACs can’t completely filter. But for most people, we would use a grounded computer/streamer to feed USB to Qutest so if replacing the Qutest power supply gives you a better sound, and at a lower cost than upgrading the streamer, why not? More importantly, just like there are people who love Chord DACs, there are others who think that they are just like any other DACs and prefer other DSD DACs or R2R DACs. Since personal preferences sometimes kick in here, if people try a power supply and believes it to be superior to the stock one for the Qutest, even if the designer thinks that the new power supply is actually worsening the performance of Qutest, I’d once again say why not? Your system, your sound, your call. With all that said, Rob Watts has used the PowerAdd Pilot Pro2 when travelling to power some of his devices. He said it’s actually a noisier power supply but at least there are no mains borne RF noise and that at least Hugo2 has enough filtering to filter out the noise coming from the PowerAdd Pilot Pro2. For those who’s interested in the designer’s thoughts on power supply, I’ve done a search specific for Qutest: https://www.head-fi.org/search/1205039/?q=Power+supply&t=post&c[thread]=869417&c[users]=Rob+Watts&o=relevance You can click on the individual comments to read more about it. There are only like 12 posts so it’s not a hard read.
  4. Actually the Chord DAC designer Rob Watts only said that for the Chord DAVE, 90% of the processing power is dedicated to the first stage upsampling. We actually don’t know how he divided Qutest in terms of processing power for WTA1 vs WTA2. But of course, your main points are still valid.
  5. I have the Mojo and Hugo2. I can tell you the difference between Mojo & Hugo2. The sonic difference is the same as the specs and designs would tell you. Mojo has a 38000 taps 16fs upsampling and Hugo2 has a 49152 taps for 16fs upsampling. But more importantly, Mojo only has a 4-element 104MHz pulse array DAC with a 5th order noise shaper whereas the Hugo2 has a 10-element 104MHz pulse array DAC with a 11th order noise shaper. Because the WTA filter is fundamentally the same for both DACs, the more taps there are, the more precise the transients so every string plucks, every drum strikes are generally more realistic. Moreover, the timbre of instruments are more accurate. The increase in elements in the pulse array DAC and the improvement in noise shaper order means that you’re going to get less noise, better SNR, so you get more microdetails and soundstage depth. Other than for cost and portability reasons, I don’t recommend anyone who can afford it to get Mojo anymore because I think the jump from Mojo to Qutest/Hugo2 is reasonably significant. That said, when I don’t want to carry Hugo2 around, I do use the Mojo. Qutest is just the Hugo2 without the battery supply and without the 2nd order analog noise shaper which is needed for the amplification for headphones. Sonically, in a system with preamps, the Hugo2 and Qutest should sound fairly similar.
  6. Every DAC actually has two parts, the oversampling + noise shaper part which is digital and then the actually digital to analog conversion part. So for ladder DACs, the R2R (chips) actually put out say 16-bit in levels at up to 192kHz (like Davide’s DAC) or 384kHz. PS Audio Directstream puts out 1-bit/1-element 5.6MHz DSD or Emm Labs DAC is 1-bit 44.8MHz. Sabre DACs I think can work to up to 40MHz for its 64?-elements. As discussed before, Mojo is 4-element 104MHz, Qutest is 10-element 104MHz. The idea of using DSD or multiple elements of PWM is that you’re trying to take the digital version of the analog wave you’ve calculated (say at 705.6kHz) and then convert it from say 705.6kHz 24-bit into 104MHz 5-bit so that the wave form in the audible range is the same but you get some ultrahigh frequency noise that you’ll just filter out with an analog filter. So the last step is really an upsampling/oversampling with noise shaping. So whenever you convert anything to DSD, you’re actually not just upsampling to say a higher sample rate e.g. 11.2MHz 1-bit but you’re also noise shaping it to that frequency. You’re essentially trying to target the DAC architecture. In Barrows’ case, upsampling to DSD256 and then feeding the noise shaped signal to the Sabre DAC’s 64 elements to reproduce makes sense as you’re bypassing the Sabre’s internal upsampling and noise-shaper and all 64 elements essentially gets the same DSD256 signal. But for Chord DACs, you cannot directly send the DAC 104MHz 5-bit signal from the PC to the DAC. So no matter what signal you send to a Chord DAC, if it’s PCM, it’ll get converted to 705.6/768kHz PCM (56-bit actually) first and then get upsample and noise shaped to 104MHz 5-bit and then noise shaped to the 4-elements or 10-elements or 20-element pulse array DAC (DAVE). If you send Chord DACs a DSD signal, the DAC will always convert the DSD64/DSD128/DSD256 into 705.6kHz PCM 24 bits? first and then convert the 705.6kHz PCM 24 bits into 104MHz 5-bit. But you’ve actually done extra math that is probably going to make the signal worse. That’s why for people who want to use HQPlayer, Jussi’s recommendation is to upsample to 705.6kHz which Chord DACs accept natively without conversion.
  7. Qutest first upsamples 44.1kHz PCM music to 705.6kHz. And then it takes the 705.4kHz to 104MHz for the 10-element Pulse Array DAC. If you do what davide does, Qutest would still take his 705.6kHz signal to 104MHz for the 10-element Pulse Array DAC. Bottomline is for your Chord Qutest, you should feed a native signal. The second thing to recognize is that all DACs upsample. Some people argue that R2R ladder DACs with NOS filters don't upsample. But in reality, even those R2R DACs can't actually take the native 44.1kHz signal. What they're doing is repeating each 44.1kHz signal 8 times to upsample to 352.8kHz so that the R2R DACs can accept the input. Because of the ultrasonic noise generated by this non-oversampling upsampling filter, you need a stronger analog filter to remove that noise. If you actually upsample (in Chord/DSD/DAC chip DACs), you can get less ultrasonic noise so you can use a different analog filter to filter the noise out. So for the DSD DACs or DAC chip DAC, the DACs have their native outputs. For DSD DACs, it might be 5.6MHz DSD or multiples of that. So any PCM music playing off a true DSD DAC has to be upsampled to 5.6MHz DSD or higher before playback. Similarly, most DAC chip DACs might have 32-element or 64-element playing at 2.8MHz or 5.6MHz so the 44.1kHz music is often upsampled to say 352.8kHz first and then further upsampled to 2.8MHz and 5.6MHz. I'm simplifying things a little since the upsampling conversion to 5.6MHz DSD or multi-element 2.8/5.6MHz also includes noise shaping. I know people who really understand DACs would be horrified by my simplifications. But I think this is a reasonable? explanation without being too much of a distortion from the truth.
  8. Yes. @barrows is 100% correct. Chord DACs always upsample. That's why you buy the DAC and it's also why most people enjoy the sound because the upsampling filter is generally superior to other products (although obviously some people would disagree). @davide256 just likes to upsample in software on his computer himself but that's his perogative. Chord Qutest would upsample the same with optical & USB. Optical might sound better because there wouldn't be ground loop noise leaking from your PC to the Qutest via USB but Toslink is limited to 192kHz PCM and standard DSD over PCM if your PC supports it. For most Windows PC, the bigger problem is making sure Windows is sending your music or YouTube sound natively to Qutest. JRiver would always send music natively to Qutest if configured properly (or by default). But Windows Media Player and YouTube would send sound based on your Windows settings so you should manually set Windows sound to 44.1kHz when using Windows Media Player and switch it to 48kHz when watching YouTube. What I actually do with my Hugo2/Mojo via Toslink from PC is that Windows is always set to 48kHz so that when I watch YouTube, it's playing natively. When I'm listening to music, I always use Tidal/JRiver/Roon so those apps would automatically switch to the correct sample rate to ensure the DAC gets native signal. Unfortunately, my PC doesn't support DSD over PCM or >96kHz PCM so I do have to downsample the Toslink to 88kHz/96kHz if it's playing at a higher sample rate.
  9. I think different DACs have different designs so it is probably unfair to overly generalize, even though all DACs would run into some fundamental issues with streamers/computers. If your Mac Mini supports Toslink output (and I think most of them if not all of them do), you can buy a 3.5mm headphone jack to Toslink adaptor and the feed Qutest via Toslink. This would technically be more optimal than USB because you can still have subtle ground loop current noise leaking from the Mac Mini into the Qutest whereas you won't get that with Toslink. Qutest Pulse Array DAC design is different than other DAC designs so are significantly more jitter immune than other DACs (although almost all DACs are fairly jitter immune) so you can get away with Toslink's increased jitter. The downside is that you may not be able to feed DSD or >96kHz PCM audio into the Qutest via Toslink (even though Qutest accepts DSD over PCM & 192kHz PCM via Toslink but your source has to support it). The Chord DAC designer considers Toslink feed to be the reference sound (or laptop via USB running on battery, not plugged into mains/ground) if people want to hear what he intended as the DACs would then be free of ground loop noise. If testing via Toslink is not possible or too cumbersome, another thing you can try is to get the Audioquest Jitterbug as an addition to to your AQ USB cable. I suspect by adding that in, I'd give it that there's a 1/2 chance there will be no change the sound, 1/3 chance the sound will improve, 1/6 chance the sound will get worse. Of course all DACs are susceptible to ground loop noise, Qutest is not significantly more or less susceptible compared to others. Adding a streamer might or might not reduce it. As a customer, the Sonore products are great as I use an ultraRendu myself but in the end, I personally ended up switching back to a USB to Toslink converter (off the ultraRendu) to completely eliminate the ground loop noise. With all this said, I can tell you that if you're already getting great sound off the Mac Mini and AudioQuest Diamond USB, you're not likely to gain a whole lot more by tweaking your system further. It's best to just enjoy the sound of the Qutest. The more you listen, the more you'll enjoy it.
  10. Yes. Sounds like you really should give BDP3 a try then. I realized while I’m super happy with my UltraRendu, it is impossible to say that you won’t run into the same problem if you own an UltraRendu instead of the SoTM products. At least with a Bryston BDP3, if it’s a persistent problem, it’s your dealer’s problem. With the SoTM or UltraRendu, if it does become a problem, it becomes your problem and something you’ll have to sort out directly with SoTM or Sonore.
  11. Sure. My local dealer had BDP3 and it sounds good. But I haven’t heard Lumin U1 or SOTM 200 Ultra. What is really confusing to me is why do you want to change streamers? Because it’s weird to switch from one state of the art network streamer to another that may or may not be SOTA. I read your posts from last year and it sounds like your issues with SoTM were: 1) microSD card gets corrupted all the time 2) you don’t like turning the sPS-500 on and off at the back But to me, the solutions to those problems are: 1) buy a new good quality microSD card and use that for the SoTM 200 Ultra (all microSD card can potentially eventually get corrupted with time. Unless you’ve tried multiple new microSD cards and they all got corrupted in which case, maybe there is something wrong with your SoTM unit which would then require SoTM repair) 2) just leave the sPS-500 on all the time. You can turn on and off the SoTM 200 Ultra whenever you want. Most power supplies are meant to be left on. I mean, at the end of the day, it’s your money and your gear. You should use them in whatever way that make you happy. But whenever you switch gear, there is always a chance that it’ll be a sonic downgrade because of system synergy. So unless you have a Bryston dealer who would loan you a BDP3 demo or you’re willing to pay for a BDP3 and then return it with the restocking fee, it’s always hard to know whether it’s a good move switch to BDP3. But yes, the BDP3 is a good product.
  12. I think we’re talking about the same thing. Rob Watts the designer says Qutest is not grounded. So as you pointed out the grounding path would go from the Zen mini through the Qutest into the Rogue. but I think the noise is not coming from Qutest as not being grounded. I think the noise is coming from a ground loop leakage current that John Swenson likes to talk about running from the Zen Mini through the Qutest into the Rogue. I may be wrong. But plugging the Zen Mini, Qutest and Rogue into the same power bar and if the problem resolved, that’s probably the answer?
  13. It is not DC offset because Qutest uses digital DC servo to get DC offset to <100uV Qutest does run hot as with most Chord DACs. Sometimes I wonder if they’re using too small a box. Kind of like those Uptone products... But both companies say their products don’t overheat because there is a thermal breaker. But I’d leave the Qutest in a well-ventilated place. I suspect your problem is a grounding issue. Qutest is not grounded. So if there is a long ground loop between your Zen Mini and Rogue Sphinx, you can get this static thing. I think there are two potential solutions: 1) Ground the Qutest and see if it goes away. You would have to use the digital coax input to ground the device I think. If you don’t know how to make a wire, you can always buy this: https://ifi-audio.com/products/groundhog/. But there is no guarantee this would work. It’s just a hunch. 2) Just make sure the ground loop between Rogue Sphinx and Zen Mini is as short as possible so that the leakage current is minimal. You can do that by making sure the Rogue Sphinx and Zen Mini power plugs are next to each other on your power bar (preferably) or power conditioner. That should reduce the ground loop impedance and not let the noise leak from the Zen Mini into the Rogue Sphinx into the speakers. I would try #2 first. I’m assuming here you don’t have other stuff plugged into the Rogue Sphinx as the more complicated the connections, the more likely you’re going to get some funny ground loop somewhere.
  14. I think if you look at the Yamaha CD player offerings, they all output at 2V so I think setting Qutest to 2V output is the safest bet for not clipping. That said, I think @Middy a good point about using 1V output too. Sometimes some amplifiers with their volume control would be more linear at specific volume settings. Meaning that you can listen to Qutest at 1V where say the S2100 volume is set at 12 o’clock to you can listen to Qutest at 2V where say the S2100 volume is set at 10 o’clock. Well, if your amplifier’s volume control is more linear and transparent at 12 o’clock than 10 o’clock, then Qutest would sound better at 1V than 2V. The original reason for having the 1V/2V/3V settings was that people were pairing the old 2Qute 3V output with amplifiers that were clipping which would obviously distort the sound. My take is that 1V or 2V should be fine and people should just set it to whatever sounds best to them. I usually think that people should use the highest voltage without clipping. But I’m beginning to understand that because of component synergies, this may not be the best choice for everyone.
  15. Just saw this today. 3V theoretically has better SNR than 1V/2V. However the reason why 1V/2V are available is because many preamplifiers and receivers clips at 3V. I would say that’s one of the major reasons why the old 2Qute had widely varying reviews because it always give out 3V. That’s why Chord added the 1V/2V option. In fact, a friend recently told me he thought his Qutest shipped at 1V/2V. He paired his old 2Qute with his receiver and it was clearly clipping to my ear but he didn’t realize it and thought that’s just the sound of the DAC. He is much happier at 2V Qutest output with his receiver. Clearly, your Elise is compatible with 3V.
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