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NOS DACs

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by brencho, Jan 6, 2016.

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  1. Madaboutaudio

    Madaboutaudio Friend

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    NOS with rolled off treble? Nah, give me Schiit's Closed-form filter + 8x upsampling anytime.

    I have the audio-gd master 7 which can be configured for NOS operation. NOS although sounds very forgiving on bad recordings, doesn't have the bite when it comes to cymbals or high energy music. Although 4x upsampling does sound quite balanced(in between sharp and too forgiving)
     
    Madaboutaudio, Oct 16, 2016
    #41
  2. landroni

    landroni Friend

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    Strange, not sure what's going on. I wouldn't expect a consequence of aliasing distortion within the 2-3 kHz band. This sounds more like "intermodulation distortion", but not sure why it would be happening here.

    Maybe @ultrabike can chime in.
     
    landroni, Oct 16, 2016
    #42
  3. purr1n

    purr1n Desire for betterer is endless.

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    Yeah. Sounds like IMD, possibly from harmonics or even sub harmonics, likely 1/2, 1/4 of 44.1kHz. Really need at least a good sound card. Using a smartphone to measure does not cut it. Going to be rife with weird stuff. Even with better instrumentation, going to have weird stuff. Lots of care is needed with these types of measurements.

    Aliasing is only a problem during sampling, not reconstruction. Think about it. But could be a problem of smartphone's sampling.
     
    Last edited: Oct 16, 2016
    purr1n, Oct 16, 2016
    #43
  4. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Not all NOS DACs do this. Depends on chip, DAC design overall, specs on paper, etc. On the Metrums, it's usually minimized if the treble signals are lower than 0dB, which they are usually noticeably lower in music (I believe). Upsampling is going to help remove aliasing and suppress images that cause distortion in the audible band. First gen Metrums already had somewhat high levels of harmonic distortion, so it's really just a perfect storm of stuff to make high frequency, high level signals sound really weird.

    I could be wrong...just speaking from my own Metrum experiences and what I learned about the topic then.
     
    Hands, Oct 16, 2016
    #44
  5. pedalhead

    pedalhead Friend

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    Thanks chaps. To the ear the distortion sounds like a solid tone (I was just using the smartphone to show the rough frequency of the distortion tone so I could articulate it). I'm really surprised at just how significant the issue is, but I suppose this is why people tend to recommend sending an over/upsampled signal to these NOS dacs.
     
    pedalhead, Oct 16, 2016
    #45
  6. bazelio

    bazelio Friend

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    I believe it to be a common problem with NOS DACs, and I observed something similar with an AD1865N-K NOS, filterless DAC that I had for a while. These "ghost tones" (great way to describe it) are almost certainly distortion products; just look at a sine wave out of many implementations. The step function is very clear to see. So it just seems like an intuitive conclusion, though I'm no DSP engineer.
     
    bazelio, Oct 16, 2016
    #46
  7. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Eventually I stopped worrying about it. It's not like I sit down and load up my 15KHz, 0dB sine wave and listen to that on my NOS DAC(s). I just wasn't hearing it as something that affected music. And, again, some NOS DACs don't do it and put out a pure sounding tone, for whatever reason. Just like some NOS DACs gloss over details and some are quite resolving. If it sounds good with music, that's all that matters. Worrying about test tones will ultimately drive you mad.
     
    Hands, Oct 16, 2016
    #47
  8. pedalhead

    pedalhead Friend

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    Wise words...it hasn't turned me off my Hex. I know it's not meant to be the dogs bollocks or anything, but fed with an upsampled signal I'm rather fond of it :)
     
    pedalhead, Oct 16, 2016
    #48
  9. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Yeah, one way to look at NOS DACs is that they're a clean slate with which to use your own software upsampler of choice. Personally, I prefer the non-oversampled sound having long experimented with various software upsamplers. If I'm going to upsample/oversample, I'd rather just go with Schiit's implementation.
     
    Hands, Oct 16, 2016
    #49
  10. pedalhead

    pedalhead Friend

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    Yeah, if I were starting over I'd probably just go with an Yggdrasil. Had one for a few weeks and I liked it a lot. There's always something else to consume my spare cash though!
     
    pedalhead, Oct 16, 2016
    #50
  11. Madaboutaudio

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    Audio-gd is tuning their NOS dac's DSP algorithms along with their DSP for their oversampling dacs:
    http://www.audio-gd.com/En audio-gd.htm
     
    Madaboutaudio, Oct 16, 2016
    #51
  12. Armaegis

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    Armaegis, Oct 18, 2016
    #52
  13. landroni

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    landroni, Oct 18, 2016
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  14. Torq

    Torq MOT: Headphone.com

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    Currently listening to a Holo Audio "Spring DAC" (Level 3, Kitsune-Tuned Edition) ... in NOS mode, and finding it to be a most engaging experience.
     
    Torq, Oct 20, 2016
    #54
  15. jexby

    jexby Posole Prince

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    Exit stage left....
    am going to listen to @Hands Spring Level 3 on Saturday and if it's "that engaging" I'll be sure to divorce from Yggdrasil first.
    but am not leaning as such, color me chi-fi skeptical.
     
    jexby, Oct 20, 2016
    #55
  16. Torq

    Torq MOT: Headphone.com

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    I generally share your Chi-Fi skepticism; to date it's been lots of hype and not much delivery. Stuff like the Gustard X20u was a total bust. And I just unloaded the Vega I had. It just hasn't worked out well so far. Most of it is raw, reference/data-sheet nonsense anyway, and I can build that myself while still having time to "read" on the can.

    Yggdrasil has proven very tough competition in my long-running major-DAC evaluations (soon to resume, no doubt here).

    So far I'm encouraged with the Spring DAC, as long as we stay away from USB as an input (even from a microRendu or big-boy Aries). What I'm hearing at this point favors I2S followed by AES. Even fully isolated USB into the Spring is a good way behind either of those options.

    (As a total aside, Sonore's web-based configuration tool completely shits the bed if you have more than one of their devices on your local network).

    Vastly preferring NOS mode to the oversampling modes on the Spring. HQ Player in various OS modes will be up next. No drop-outs with multi-rate DSD from OS X/mac OS ... unlike certain (ALL) Chord DACs I've tried.
     
    Torq, Oct 20, 2016
    #56
  17. Torq

    Torq MOT: Headphone.com

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    Just a quick teaser picture; you'll have to excuse the lame cell-phone photography - far too lazy to grab the Leica and tripod (maybe tomorrow):

    Basics.jpg

    Let's see ...

    Woo Audio WA5-LE Mk2 w/ all parts upgrades. Normally I run Takatsuki 274B and 300B w/ Sylvania 6SN7GT tubes; I've swapped those back out and have Sophia Electric Princess 274B and 300B w/ RCA signal tubes installed while I am showing the house (too many excited children/adults with sticky/over-zealous paws).

    Ragnarok and Yggdrasil are obvious.

    Spring DAC is connected here via AES/EBU XLR out of the full-spec Aries with one of my own "special"* cables and in NOS mode. Proper DAC pictures will follow once I get a bit more time listening.

    Feed is Red Book PCM from Roon.

    Abyss, HD800S and LCD-4 on show. Utopia is at the other house at the moment, along with the not-long-for-this-world RedNet 3 (no change in AOIP allegiance, just switching to the D16 AES).

    Odd unit on the side is a Tascam DR-100Mk3, which gets used for my needle-drops.
     
    Torq, Oct 20, 2016
    #57
  18. lukeap69

    lukeap69 Pinoy Panther

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    Perhaps it's time to start a Holo Spring DAC thread on its own so @Torq and @Hands can provide more detailed impressions?
     
    lukeap69, Oct 21, 2016
    #58
  19. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    I call dibs on starting the Spring thread! ;) Just waiting on tomorrow to do head-to-head comparisons with other DACs. I want to make sure it has a solid start. Maybe @Torq and I can collaborate before posting, or anyone else that has heard/owns one.
     
    Hands, Oct 21, 2016
    #59
  20. Torq

    Torq MOT: Headphone.com

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    Works for me!

    I took the day off to be self-indulgent and just sit and listen and do some first-pass comparisons with Yggdrasil.
     
    Torq, Oct 21, 2016
    #60
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