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Chord Electronics - Hugo 2 - The Official Thread

Discussion in 'Portable Source Gear' started by ChordElectronics, Jan 5, 2017.
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  1. Rob Watts
    I promised that after Can-Jam Singapore I would publish my slides, so here goes. Apologies in advance if you find it too technical - but we are dealing with an immensely complex  subject, and I have tried my best to simplify it as much as possible.
    So the opening slide.
    So here I am talking about the WTA filter, and I have assumed that the reader is aware of the WTA filter and why the recovery of timing of transients is important - so I assume you know already that more taps gives better accuracy, and much better sound, and that moving from 8 FS (output at 352/384 kHz) to 16 FS (output at 705/768 kHz) is seen as a benefit in SQ due to the improved time resolution of the output.
    The FPGA is jam packed - I use all of the available DSP cores, all of the memory, and 99.8% of the logic too. The downside to all this is now the FPGA uses a lot of power, around 800 mW.
    The output from the WTA 1 is now passed to another WTA filter (WTA 2) that takes us from 16 FS to 256 FS (output at 11.289.6/12.288 MHz) so now the WTA is working to a resolution of 88 nS.
    The filter option is actually a big departure for me - I go for what is technically correct (assuming it sounds best), and don't give options. Now the HF filter is a technically correct option - as using the HF filter with HD files can reduce HF noise from the recording, which is not music but noise shaper ADC distortion and noise - if this gets into the analogue parts it can cause more noise floor modulation, so removing it will make it sound smoother. So having the HF filter is a technically valid option. But the 256 FS filter is always the more accurate option, and will recover the timing much more accurately than not using it. So why did I add this as an option?
    Several reasons. I thought it would be cool for people to actually hear the effect of the WTA going from 16 FS to 256 FS. Normally, I do lots of listening tests, and so build up knowledge to allow better designs and future improvements, so I thought it would be good for one to hear the effects of 16 FS to 256 FS. What you hear is an immediate change in the ability to perceive the starting and stopping of notes. This quality is very different to the usual WTA benefits (better timbre, pitch, instrument separation and focus etc) in that being able to perceive the starting edge of a signal (the initial pluck of a string or how the piano sounds when instantly hitting the key) all depends upon timing accuracy going from uS down to tens of nS  - so I thought it would be interesting to actually hear what I am talking about directly. Now this filter will be called the incisive option, as calling it Hugo is a bit confusing. Its incisive because you can now perceive the starting and stopping of notes much more clearly - and when the brain can't perceive the leading edges, then it becomes a blur and things sound soft.
    The second reason for the filter options is that the incisive revealing nature of the filter does make it sound brighter. Now it is absolutely technically more accurate; it only sounds brighter because the brain can now more accurately perceive the starting and stopping of notes, and the starting and stopping transients have a lot of high frequency energy. When the brain can't perceive something, it simply ignores it, so it then sounds unnaturally soft, in that this is not truly transparent. But sometimes when you have say a bad bright recording, or say hard headphones, having a filter that allows you to hear high frequency energy may be a bit too much. But for sure you are using an aberration to hide another problem. So my advice is this; if you use the 16FS option (orange or red) all the time, then consider getting a warmer set of headphones, or trying out EQ. Normally you should be using white or green - I run with green all the time as its useful with 192 recordings.
    So this is fairly straightforward, and with conventional DAC's you can easily measure noise floor modulation. I will be showing the measurements shortly.
    OK this is a quick summary of the difficulties involved an having a DAC that has no measurable noise floor modulation, and there is a great deal more besides, as noise floor modulation occurs from a myriad of problems within DAC's.
    So this is why I have to filter DSD sources - as without it we would get large amounts of noise floor modulation, and other problems - gurgle noise, distortion etc.
    With this filter I wanted top match the abilities of the DSD+ mode in Dave, and I believe I have - I know get that level of sound quality. But to do that I had to have incredible levels of filter attenuation - so with much better than 200 dB, I ensure that THD and noise from the analogue is entirely limited by the DSD 64 digital performance - there is no added THD or significant noise that is not present on the file.
    So this is employing the knowledge gained from Dave with noise shapers, so now I am getting much better perception of depth and detail resolution. Incidentally, I have now designed and listened to dozens of noise shapers and every time I got the same result as Dave - better noise shaper performance gives better depth, and the smallest small signal error is audible in terms of depth truncation.
    This is the same cross-feed on the original Hugo - indeed its the only piece of code coming from Hugo! But there was an interesting story with it. When developing products you go through many stages - and formal listening tests plays a major part. But then there is the part where you are listening for pleasure, and at these times it is valuable because you can see the scale of where the sound quality is, and its only by listening without consciously testing that one can asses musicality or the ability to get emotional with music. And that is the real reason to be doing all this.
    So last December one of the prototypes was ready for listening, and I took it on many flights. I was listening to music, and bells were being played - and the depth was so convincing I thought it was in the plane, and not on the recording. This was a major surprise, as getting headphones to portray good depth has been a major issue. It turned out that the cross-feed setting was crucial - with it off, the sound-stage collapsed, and with it on, I got decent depth from headphones. 
    Measurements are vitally important, as if you are concerned with making truly transparent devices - and that is the only way ultimately for musicality - then measurements plays a vital part. Now its true that a good sounding device can sound better than a better measured one; but for sure, when you improve the measurements, (now matter how small the measured change is) and with all other things being equal, you will perceive an improvement in SQ.
    Additionally - many manufacturers make bold claims - sometimes with the best of intentions (they genuinely believe it is better), sometimes with the intent to deceive at worst or at best to extract cash from you - and then from the measurements you can see that they are talking nonsense. Moreover, I can tell from a suite of measurements pretty much how something will sound, and moreover what is the intent and capability of the designer or design team. So although it is highly fashionable to talk about not caring about doing measurements, to me it is throwing out the baby with the bath water.
    So I made some claims about noise floor modulation, and here it proves it - absolutely none, and zero an-harmonic products too.
    Now I should add I often see so called measurements of my products on other threads using poor quality test equipment, and hence "proving" that xyz is not that good after all. So I should add that Hugo 2 outperforms test equipment easily. A measurement is not objective reality, it is just data subject to error done at a particular time with particular test equipment. And my DAC's require the absolute state of the art test gear - in this case the APX555. This is the only test equipment that is capable of measuring noise floor modulation, as ADC noise floor modulation is way bigger than Hugo 2 - and the APX 555 uses a special technique with 4 ADC's to overcome the ADC limitation.
    We can see also the extraordinary low THD - this is only beaten by Dave.
    Now one of the features I used was the second order analogue noise shaper OP stage that first appeared with Dave. The benefit of this technique is that it eliminates crossover distortion, as high frequency distortion does not significantly increase with a 33 ohm load. in the past adding a load of 33 ohms would harden up the sound - now it makes no difference whatsoever.
    This shows how isolated the DAC and amp is from the power supply and each channel.
    So proof again that is immune from jitter - no artifacts at all. The only thing you can see is a tiny residual at 11 and 13 kHz these are artifacts from my APX555.
    I am very happy with these measurements; I am confident that no other non Chord DAC at any price comes close to this level of performance.
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  2. jmills8
    Rob, Thanks and wondering if these slides can be put into a video on youtube. PS with a voice on it aswell.
    Peter Hyatt likes this.
  3. x RELIC x Contributor
    Remarkable measured performance, especially for a portable device. Well done @Rob Watts, very well done!

    And not just any voice, but that of Morgan Freeman.

    Dancing caterpillars would be good, too, but hey, if you can't swing that, we understand.
    JimboDimbo and phonomat like this.
  5. SearchOfSub

    I remember when Mojo first came out people said it sounded as good as Hugo. Anyone who have heard both knows it was complete waste of time reading through those posts.
  6. Hooster
    These are fantastic measurements, many thanks for posting them. I hope that some day I will possess speakers and headphones that are good enough to let this shine through. Well done.
  7. tonyl59
    Many thanks, Rob, for sharing this with us. What shines through is the pride you have in Hugo 2. I was very interested to read more about the filters and crossfeed; it will be great to be able to to switch these in and out so easily and see what they're set to (vs original Hugo). I am really looking forward to getting mine (very soon, I hope!).
  8. Christer

    Maybe the people saying so  were playing  typical electronica pop rock music that was incapable of revealing any real audible differences between the two?
    Yesterday I went to the Adelphi in Singapore hoping to find HUGO 2 demo units having landed  at some shops there. But no one seemed to be expecting any demo units yet.
    At Jaben there was no Hugo 2 but a lady seated on a chair clenching a piece of plastic between her teeth while a shop assistant was busy sticking some plastic mould into her right ear.
    It turned out he was personalizing her iems.
    Among other things to do there,one shop was stocking the Focal Utopia which I will audition tomorrow. And I did get to hear a 150000 SGD speaker system being setup  in one shop there.
    The soundstage from those huge hornspeakers definitely had  both  realistic size and power. BUT as so many dealers do these days they played some low res rbcd res pop material which clearly showed how  completely inadequite low res digital is at resolving the human voice as it sounds live or via hi res digital  or even a good old LP.
    What a waste.
    If I had brought my laptop I could have offered them some much better material for setting up a highend system than what they used.
    It was really painful to hear how distorted and artificial the  female voice on that track sounded on a system that most probably is  able to reproduce well recorded  music  very realistically indeed.
    I walked away like so  many times  before, wondering why so few seem to realize that the more resolving a system is, the more obvious the limitations of low res digital  becomes.
    Some shops were  also stocking the  ML 15A .That is a speaker I would also  like to audition with suitable material  capable of sorting" the wheat from the chaff".
    And one that I might even be able to afford unlike the horns playing a  crap res recording in another store.
    With a bit of luck HUGO 2 will be on demo here when I return from Sabah in a couple of weeks though.
  9. jmonty
    Thanks for the explanations and mesurements!
    I note that you are comparing basically with Dave, so it implies that Hugo2 is (at least) tecnically better than Hugo TT?
    I like the USB input is better isolated from RF interferences despite it is not galvanically isolated. I hope the coaxial input will also work as well as the USB.
    I really like the filters you included to "fine tune" the sound with the headphones and amplifier/loudspeakers systems we have, as well as our preferences.
    I am wondering what kind of headphones would sound better in terms of dynamics, natural instruments and voices, deep, etc... paired with the H2.... a lower impedance or mid impedance? I am thinking in pairing it with a Fostex TH900 (25 ohm 100db). I like natural sound with "body" and stage for classical and jazz with instrument separation. I assume it depends on the timbre/sound preferences too. Sorry if this is a dummy question.
  10. halloweenman
    Wow, thank you Rob. The filters are a useful addition. Will be interesting to see which fits best in my system. I listen almost exclusively to 16/44 Apple lossless cd rips. Would i get any benefit therefore from using the green HF roll off as apposed to white filter or is this more for hi Res audio?

    The USB tests are a relief in that with my new generation battery powered macbook i need not worry about galvanic isolation or jitter.

    I'm fully expecting the sound of Hugo 2 to be somewhere between my now sold hugo TT and Dave. Can't wait. I did demo Dave at home twice previously and didn't take to it, I suspect due to brain break in (perhaps we are not used to listening to music at home with such accuracy with so little noise and distortion) and to speaker \ room issues rather than Dave itself. I've ended up downsizing speaker (from ATC SCM40A to SCM19A) to reduce bass energy and installed decorative acoustic panels on reflection points. Dave magnified the room issues with bass boom/low frequency standing waves and high frequency room reflections.
  11. phonomat

    In this case I would not recommend the TH-900. Using it with the original Hugo, I did not like the pairing at all, and "body" was exactly what it missed. Perhaps the warmer filters might help with that, but I wouldn't buy the TH-900 a second time, as the recessed mids make it sound way too lean for my liking. Of course, YMMV.
  12. jmonty
    Thanks. Wich headphones would you recommend tor the Hugo ?
    Here somebody paired Hugo+TH900 and he is happy with them:    http://www.head-fi.org/t/748410/hugo-with-fostex-th900-silverdragon-vs-hugo-with-mcintosh-mhp1000
  13. flyte3333
    Thanks so much Rob. You're making me upgrade from a Mojo to Hugo 2 ! I've just put my pre-order in :)
    Is the white setting essentially the raw 'no filter' setting?
    And why do you prefer green with 192 recordings in particular, over the white setting? Of course this is a personal preference but technically speaking, what is the green setting doing differently to the white setting for 192 recordings?
    And just for clarification regarding "But the 256 FS filter is always the more accurate option, and will recover the timing much more accurately than not using it" is this only referring to the white filter setting, or includes the green filter setting?
    Many thanks in advance
    Peter Hyatt likes this.
  14. flyte3333
    Yes indeed ! I have been using the Mojo for both desktop and main DAC in my listening room and it's been doing an insane job.
    My desktop setup: Surface Pro 4 > iFi iDefender 3.0 + iFi iPower 5V> Curious Link > iFi USB Purifier2 > Curious Mojo Link> Mojo charged by iFi iPower 5V > Mojo > Sennheiser HD800S
    Main HiFi setup: same chain > Mojo > Analysis Plus Silver Oval iPod Cable > PrimaLuna Dialogue Premium HP Integrated > GoldenEar Triton Ones
    I would love to have the PrimaLuna HP amp at my desk to power the HD800S but it's too far from the listening room and weighs about 35kg. Too heavy to carry back and forth.
    I need more high frequency action though - at least the option for it - hence I need the Hugo 2. I'll be selling the Mojo because I need more HF action with both my cans and speakers. I loved using the Mojo in both setups.
    For ultra critical listening I like running the Mojo (and next the Hugo 2) from the battery, which is why I'm going for the Hugo 2 as opposed to a cheaper but just as good 2Qute. But also having the filter options and the very latest FPGA code from Rob and almost Dave level measurements are more reasons I'm going with the Hugo as opposed a 2Qute.
    My local seller mentioned he'd have stock end of March but a friend in Singapore said release is early April.
    Can't wait !
  15. Rob Watts
    No the white is with the WTA filter 2 engaged - so we have the WTA working at 256 FS, so timing is more accurate.
    The green makes a very big difference with 96 and 192 - its easy to hear - but it is very much smaller with 44.1 as there is almost no noise to filter out.. 
    This is simply due to the much larger levels of noise coming from HD sources - and this noise is artificial, as it is ADC noise shaper noise. Needless to say, one of the things that Davina will do is not have increasing noise shaper noise within the 768 kHz sampling rate, but standard ADC's have large amounts of this noise. The HF filter is second order, and has a -3dB at 40 kHz, so noise above this is prevented from causing noise floor modulation in the analogue parts of the DAC.
    No noise floor modulation means a smoother and warmer sound, exactly as I hear.
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