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New Audio-gd R7 (R2R 7) & R8 Flagship Resistor Ladder DACs

Discussion in 'High-end Audio Forum' started by Currawong, Jun 30, 2017.
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  1. JaMo
  2. christianvogel
    Hi @FredA, I may be wrong but what I remember from Jos from Magna Hifi, the FPGA is always in play.
  3. Wynnytsky
    where can I find docs [or a blurb] on what the different combinations of ATT jumpers are purportedly accomplishing? (and all the jumpers for that matter)?

    I take it NOS can be accomplished by jumping IPS0 & 1, or jumping S2?
  4. christianvogel
    S2 switches to NOS, ATT0 and ATT1 switch NOS mode and IPS0 and IPS1 switch the OS mode.
    See halfway down the page here: http://www.audio-gd.com/R2R/R2R7/R2R7EN_Use.htm

    As for what each NOS mode does, I saw it somewhere described that:

    - NOS1: direct and most compatible NOS mode
    - NOS2: using FIFO (I assume FIFO buffering)
    - NOS3: accurate mode (preferred by mr Kingwa but not selected by default because it is more critical)
    Last edited: Nov 2, 2017
  5. FredA
    That's what Kingwa seemed to imply as well in an email exchange. I guess then mode 2 preserves the timing of the source better for whatever reason. I will give it a try.

  6. Wynnytsky
    From this I gather NOS3 is the least smooth ...
    and from this I gather NOS3 is the most smooth ...
    Regardless of which one is right, does NOS2 split the difference (or is this not a linear scale)
    And once I know which NOS is most accurate (least smooth), I'd like to know which of the available OS modes that best resembles (2x, 4x, or 8x)?

    I read tech docs a lot, and to me when I read those two tables (S2 OFF vs ON) it's not clear why I can't engage NOS with S2/IPS0/IPS1 => 0/1/1
  7. christianvogel
    Hi @Wynnytsky,

    I know it sounds counter intuitive, I said mode 3 is more accurate as I read from mr Kingwa that it is the most accurately compensated. However, mode 2 uses FIFO mode, which may have benefits in suppressing jitter or noise. When I hear mode 3, it has a more smooth sound, and is a bit less dynamic and sounds (to me) more coloured, but also very pleasant.

    I suspect is that mode 2 and 3 do more than one thing differently. In mode 3 I hear more harmonic distortion (a little like when I connect my tube amp), and mode 2 to me sounds cleaner and things have more impact, which could mean more inharmonic distortion.

    Hope that makes sense, and of
    course it is just what I hear, which of course tends to be highly subjective :)
  8. christianvogel
    I agree that doc is not too clear.

    To activate NOS, you simply need to put a DIP on S2. Once you have done that, you must use ATT0 and ATT1 to select the NOS mode (IPS0 and IPS1 are only used for OS mode):

    - no dip on either ATT0 or ATT1: NOS3 mode
    - dips on both ATT0 and ATT1: NOS1 mode
    - a dip on only ATT1 (not ATT0): NOS2 mode

    Also, in case you do not like NOS and prefer OS mode, you can also see how you like dithering by putting a dip on DITH. This theoretically should give you more dynamic range in OS mode.

    PS: based on that you said you prefer a more neutral and accurate sound, I suspect your preference will be either OSx8 or NOS2. Both sound very clean (NOS2 only with a good I2S source, OS is more lenient on the source).
    Last edited: Nov 2, 2017
  9. Wynnytsky
    I take it NOS2+PLL would offer the best jitter rejection/suppression but also be the most fragile lock. I look forward to testing that via USB and I2S.

    and while I have your attention...
    To engage NOS I'm jumping S2 and then ignoring the top table - Right?
    The bottom table says IPS0/IPS1 are "Reserved" so I can ignore those jumpers entirely - Right? (or am I wrong and I must still jump IPS0/IPS1)
  10. FredA
    Listening to NOS2 now.

    The attacks are not as sharp but the soundstage is a little better. More depth as well and the sound is more laid back. Overall, it's more relaxed, smoother. Better bass presence but maybe not as defined. It's quite different, that's for sure.

    I will try software oversampling with it and see.
  11. christianvogel
    Sir you are correct. The top table is only for OS, the bottom table is only for NOS. You need no jumpers for IPS0/IPS1.
  12. christianvogel
    @FredA I tried OS through Roon with the R2R-7 in NOS, and I like Kingwa's OS a lot better. Curious how you will experience it.
  13. FredA
    These are only first impressions but i like what i hear with nos2 and 2x overampling in audirvana. It's like a mix of both. The bass goes lower, lower than with the os mode as well, the attacks are sharper than with only nos. Still the sound is smoother than with the nos OS. The attacks are not as sharp still as with the os mode. The soundstage is similar to nos2 without software oversampling.

    I will give 4 time oversampling a try now.
  14. FredA
    I use the Izotope upsampler built in audirvana with the sharpest slope, max phase linearity, max anti-aliasing, cut-off freq. at 1.02 Nyquist, and a 1000000 sample window to compute the output. The latter makes a significant improvement from the standard izotope settings. You get better definition in short.

    With 4x oversampling by izotope in nos2, i think i have a sound i like more than the os mode. It's more accurate. And smoother. And more laid back. I am gonna keep this configuration for a while and see. So far i like it a lot.
    Currawong likes this.
  15. Wynnytsky
    And if I stay on the top table (not jumping S2), what could I expect from this combination?

    if not NOS, then perhaps it's an easter egg that loops a MOD/MIDI track of the Chinese national anthem buried in the FPGA
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