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

Discussion in 'High-end Audio Forum' started by Currawong, Jun 30, 2017.
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  1. FredA
    In the long run, the audio-gd dacs (I would the same about my M1) are really enjoyable. My M7 gave me more enjoyable playback hours than i could ever have dreamed of and for this, i will alway be grateful to Kingwa and audio-gd.
     
    Last edited: Dec 30, 2017
    HoloSpice likes this.
  2. Wynnytsky
    You can earn this kind of wisdom from a long expensive journey in DAC procurement
    or you can pluck it from pg53 of the r2r7 thread
     
  3. Wynnytsky
    for a while my friends have been putting these 35cent pads under everything (speakers included)...
    http://www.parksupplyofamerica.com/product.php?id=DIVMP2C&fam=PZLFZCU4A8RF&addons=y

    I tried them under my amp and the sound was immediately worse. I assumed this would be something that I'd be lucky to discern over time, so the immediate effect was a shocker and I had to add/remove them a couple times before I felt comfortable telling the story.

    The other day my friend put them under his PSAudio Direct Stream and it was immediately a must-try. So last night I slid 4 under the R2R7 and it's like I got a double dose of the smooth firmware with nice tails and extension. The 2" thick maple in my rack makes it very heavy and everything has a very strong connection to the floor -- not sure if that makes the pads more effective? Also, I doubt a light weight DAC would be effected by pads this much. After a week of this I'll want to hear how the accurate firmware sounds with pads.

    4 of them cost $1.40 (+$5 for shipping). You'd have to order 26 of these pads ($9) before the cost of the product caught up to the shipping.
     
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  4. FredA
    I am back with the accurate fw, but with jumpers on att0 and att1 (only). I wanted my dac to sound more like my old m7 as signature goes. Mission accomplished. First I had the accurate re-installed and found it not forgiving and not laidback enough. Then i had the idea of adding the secret setting's jumpers used in 6 moon (att0 and att1 jumpers on). Bingo! Piano and bass are fabulous and you get better rythm as the attacks are sharper. I use no sw upsampling right now.
     
    Last edited: Dec 31, 2017
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  5. FredA
    Now to emulate the sound of the M7 even better, the r2r 7 would have to sound more tubby, which would be a great plus to me given how neutral my setup is. But make no mistake. The r2r 7 is a cleaner, tighter and more resolving DAC. The old M7 has a magic touch that makes it so visceral. It's so emotional.

    To be fair however, the last time i listened to the m7, two days ago, i used the di2014. With the M7, transports do change the sound significantly. The euphonic attributes i pointed with it could be the result of jitter. It's crazy how different jitter charcteristics impact the sound. They can change the balance drastically. But not very significantly with the r2r 7 because of the very effective reclocking it does. As a matter of facts, it sounds almost the same from the amanero input compared to the singxer f-1 through i2s. Only the bass changes, going a little lower and being a little tighter with the f-1. Same with the optical input from my oppo blueray. This tells you how good the singularity board is.

    Maybe introducing jitter in a controlled mathematical way would be effective in producing different signatures on purpose. For instance, the jitter at the output of the M7 could be characterized and mathematically emulated. At this level of conversion accuracy, my current view on things is that jitter is what determines how a dac sounds (besides the output stage, which is made as neutral as possible, or tubby sometimes on purpose).
     
    Last edited: Dec 31, 2017
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  6. astrostar59
    To make matters even more complicated, Steve Nugent of Empirical Audio (off-ramp convertors) who had spent a lot of R&D time on these types of issues and convertors, has recently come up with a new Jitter measuring process. Before all Jitter specs was taken as a 'sound bite' a small capture and a measurement of the accuracy (or not). He has now shown Jitter measured over the entire duration of (for example) an eight minute track has hot spots where is drift more in clusters. So not constant and varies over time. Thus any Jitter reduction capabilities has to be able to cope with the ebb and flow of Jitter as it overshoots or undershoots. It is not just about a set amount and that is it.

    A powerful reclocker in the DAC is probably (in my mind) going to work best. As that at the end point of Jitter (timing inaccuracies), and in theory at that end point it gets fed to the DAC chip before further Jitter can be introduced.
    There is also digital noise to consider. The amount of isolation in the connection device to the DAC will affect the final sound as well. And as said above, this level of Jitter and noise rejection will be different in various DACs. I would say the level of Jitter and noise rejection will probably affect the final sound quality more than the conversion method used. Then taking this further, it is interesting how many modern DACs still don't take such things seriously enough, lets face it IMO 90% at least of DACs will now be fed by a streamer or PC based source, not an old school CDP.

    On another related subject, the sound you get can be affected by how aggressive the digital fllter is. I am still not convinced true R-2R actually needs a filter, it seems to create more problems than it fixes.
     
    Last edited: Dec 31, 2017
  7. FredA
    At the output of the reclocker, to carry the signal the dac modules, twister pairs would be best, like in an rj45 cable, leading to differential inputs, thus minimizing cross talk and contamination overall. DACs are really tricky. They are also sensitive to high-frequency noise (in addition to low-frequency noise) in a way that is very insidious. Sunddenly, your dac sounds lifeless and you just can't figure what wrong. You pick up noise through the grid or it's airborn.
     
  8. Wynnytsky
    airborne noise is real!
    This week I finally found the source of the faint buzz that sometime effected my left speaker (while no speaker connects attached!)
    It wasn't charged coils in my xover, it was the fluorescent bulbs in an upstairs bedroom. I solved the same problem a year ago (but on a much bigger scale) when there were 4 of those bulbs in an upstairs bathroom.
    Because this only effected one speaker, I'm guessing those bulbs inject noise or DC back into the AC line, and that line is probably running down the plaster wall that the left corner horn is creating a seal with.
    I know that line is the really old cotton wrapped copper, so that probably doesn't help.

    Did a weeks worth of listening in a day, then flashed accurate and went with the 6moons settings as well (PLL on though). Definitely more inviting than what I remember w/o the cork footers.

    If you mean USB reclocker/filter (not interface) then I agree. My USB cables which are more dynamic seem to behave better with an Intona or W4S recovery in play. I have one short USB cable a friend made that seems to have just enough dynamics w/o wanting a reclocker. And yeah, tone/pitch aside, I hear more information when there are fewer terminals for the signal to pass through.
     
  9. astrostar59
    No, I was referring to the digital filter. I am not sure, but I believe some R-2R DACs (non upsampling) still apply a digital filter to 'remove' the aliasing or copies of the wave form further up the spectrum. I understand that logic in DS designs, but the NOS R-2R DACs I have heard and seem to prefer (Zanden, Audio Note) have no filter. Certainly my spare AMR DP-777 has a filter.
     
  10. FredA
    I think audio-gd applies a digital filter in nos mode. The main reason is otherwise the highs would be rolled off. Digital signal processing notions, quite hard to explain without getting into mathematics. Another reason is non linearities can bring the high freq noise back in the audio band. Audio-gd sure uses digital processing in nos cause there in no roll off in the response.
     
    Last edited: Dec 31, 2017
  11. FredA
    Airborn stuff: static electricity on blankets makes my ddc pop..

    I also am with the six moons config except i let the dac do the oversampling (8-time). I tried adding 2x in audirvana. I prefer letting the dac do it all. More dynamic.

    With this new config, i really like how sharp the attacks are and deep the bass is. Piano is just so much better. It's listening to the M7 that initiated all. Such a great dac. In the long term , the r2r 7 will get much better, but the M7 is such a tough act to follow and not far behind, and i could conceive that someone could prefer it. Add some tubbiness to the r2r 7, and it's game over for the M7 however in my opinion.
     
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  12. FredA
    Another point on the accurate firmware. Since it basically increases the driving capacity of the i2s output to the dac modules, i would be inclined to think there will a break-in phase since more current goes the i2s occ wires. What makes me say that is i had a better sound right after flashing the new firmware. Now, it's a bit compressed/lifeless in comparison. But slowly getting better it seems. Or i am just hallucinating. I doubt it cause on Friday, with my friend who was to pick up the M7, we noticed something strange in the sound going from the i2s input to the bnc one, using a silversonics cable. I thought, i must have inverted the cable's direction, as a matter of fact. I switched it and everything came back to normal.
     
  13. mocenigo
    Completely understandable. You should know that inverting the cable's direction makes the DAC try to send bit toward the source, making it much more difficult for the music to flow effortlessly!!! :wink:

    Happy new year!

    Roberto

     
  14. FredA
    Happy New Year. Enjoy a good Ripasso in good company!
     
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  15. Currawong Contributor
    Tempting that it is to go through a number of messages and demolish the nonsense, I'm just going to pick on one small error.

    You need to remove the "(non upsampling)" from that sentence. The way I first read it made me think that you were saying that a NOS DAC can have a filter and still be NOS. Up-sampling and over-sampling are the same thing. :)
     
    bunkbail likes this.
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