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Chord Electronics - Hugo 2 - The Official Thread

Discussion in 'Portable Source Gear' started by ChordElectronics, Jan 5, 2017.
  1. Luvdac
    @Rob Watts. Hi, I've got an Intel 8th gen i7 server running audiolinux with roon and hqplayer. I cant get linux to send out native dsd to the hugo 2. Only upto dsd256 over dop. I would like to use the hugo's native dsd512 capability without having to resort to a windows machine. Has Chord a driver for linux that would enable native dsd? If not, it would be a great service to hugo dac owners who are running linux based servers to stream music if Chord could provide one.
    Most music servers and bridges are running some form of linux and this is quite a large market out there.
    If there already exists a linux driver, please do let me know where to download it. Thanks!
    Last edited: May 17, 2019
    111MilesToGo likes this.
  2. Rob Watts
    @Currawong replied well about this, but to reinforce that reply there are three reasons why it must be converted to PCM. Firstly, DSD is not a transparent conversion process; every time you re-run a DSD modulator you get more THD and noise, and losses in small signal resolution. PCM can be made completely transparent (I say can as actually it's not easy even with PCM!) so we can add volume and crossfeed without degrading transparency. Secondly, DSD needs to be converted to PCM so that the pulse array DAC can convert to analogue without significantly degrading the output - it's impossible to convert regular DSD to analogue without adding significant THD, noise floor modulation and small signal degradation. Using pulse array, I can recover the DSD64 signal so that the THD and noise and small signal resolution is format limited, not conversion limited - so you will be limited by DSD innately not the analogue conversion. The third and final reason is DSD has huge amounts of HF and RF noise - and this must be filtered out. It's much more transparent to do the essential filtering digitally than using complex analogue filters.

    I don't design the USB hardware, firmware or drivers - but Chord are aware of the issue. Of course DSD512 support on linux is pretty niche (have you seen the size of DSD512 files!) and with only a few actual music tracks available... The irony is a 44.1 track via M scaler will actually sound better (all other things being equal of course), and of course will have file sizes that actually allows you to listen on the go!
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  3. Currawong Contributor
    Buying DSD512 files I reckon is crazy. I have a streamer from a manufacturer here that, when I asked why it doesn't do above DSD128, the engineer said because the electronics would have worse performance at higher rates. Also, who knows what high-frequency ADC noise has been dumped in them from the recording process. I also wouldn't be surprised if the processing of 1GB DSD512 files don't contribute increased noise in the electronics processing them. That is something I've been curious about.
    Last edited: May 18, 2019
  4. 111MilesToGo
    @Luvdac: I‘d like to second your request. In fact, I had been asking for the same, and got the same answer. My knowledge for sure is incomplete, but I figure it takes contributing a piece of code to the Linux Kernel. Please do a search of this thread here for ”quirks.c“. You will get referenced to three posts of mine last year, plus web references therein.
  5. Hifi2jungle
    Great! Thanks Rob. I will order the TT2 and will concentrate on PCM in the future. Will try to convert dsd files to PCM before sending in to the TT2 and listen to the results. According to my understanding this would make even more sense. What do you think?
    miketlse likes this.
  6. AndrewH13
    Keep meaning to try converting my DSD to PCM. I expect dbPoweramp will do it. Will conversion be lossless?
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  7. Hifi2jungle
    Lossless yes but it can happen that the original character of the dsd file is getting lost. Would be keen to hear what rob says: converting dsd files to pcm on a pc or let tt2 do the job?
    514077 and AndrewH13 like this.
  8. AndrewH13
    If it’s the slightly softer character of DSD that gets lost, that’s good by me :)
  9. GreenBow
    I honestly don't think you can go wrong with the TT2. I bought one, have had it just over a month. (I am a little concerned about how warm it gets, but then all Class A gets warm. It's normal really.) It could make stacking an issue though, depending on what you stack with. Chord show the Ttoby, TT2 and HMS, all stacked. The TT2 and HMS both produce heat. I think I would build a stand if I had those products; one that allowed for spacing and heat distribution.

    At normal room temperature though, the TT2 stays only warm. Just when it gets hotter than 25'C, the TT2 gets a bit hotter. If I recall correct though the Hugo 2 would get a bit warm in a hot room anyway. When I had it on my desk, I would have wooden slats under the feet, to give it desk clearance.

    The TT2 only really get warm after being on long, and on hot days though.

    EDIT: TT2 has been on for ten hours today. In room temp 22'C, it is still barely warm on top.
    Last edited: May 19, 2019
  10. Rob Watts
    In a word no. Lossless normally applies to compression, when you are trying to recover the original data perfectly - and a DSD to PCM filter won't do that - you are on purpose trying to filter out the RF noise and distortion from the DSD modulator in order to improve the sound quality - that is making it more faithful to the original analogue signal from the mic.

    The filters built into DAC chips are very simple moving average filters and offer something like 60 dB attenuation, or not much. The filters used in PCs used for DSD to PCM are not published performance, and are probably simple ones - nothing like the better than 200dB rejection at 88.2 kHz and above I get with the filter that is in Hugo 2, TT2 or the M scaler. And this crazy level of performance is important subjectively. Moreover, the other benefit of the filter within is that the bit depth conversion is much more accurate - I can guarantee -301 dB performance with my 11th order truncation noise shapers.

    So keep the conversion within the DAC if possible.

    No I am afraid that's not possible - once information is lost by the DSD modulators, it can't be recovered! And DSD modulators have amplitude related timing errors, (that causes the softness) and small signals are not perfectly reproduced (that gives you the flatter depth perception). And sadly it's impossible to correct for these errors.
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  11. AndrewH13
    Thanks Rob, very informative!
  12. paulgc
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  13. Peter Hyatt
  14. musickid
    Thanks for the link Paul will make interesting reading.:book:

    Were you using hugo2/mscaler and how is it or was that someone else?
    Last edited: May 20, 2019
  15. paulgc
    Just H2 for me. Other mobile is Poly/Mojo/Continental V5.

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