MD x Airist x Sosolar: RDAC design mysteries

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by bimmer100, Jun 5, 2018.

  1. purr1n

    purr1n Desire for betterer is endless.

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    Last edited: Jun 5, 2018
  2. 9suns

    9suns [insert unearned title here]

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    @rshuck I think both (Airist & MD) are responsible.

    First, we have Airist, with all the PHD, nuclear stealth rubber dong bomber e-peening, whose only product is a headphone amp that, according to experienced members here sounds like crap and is built like crap, was released at 2k dollaroonies but dropped to 750$ (talk about value for the money!). IMO, there's no way these people can make something as complex as a R2R ladder DAC, let alone a good sounding one, and let alone a good sounding one at a low price, so they copied one from a chinese enthusiast that sells boards on Taobao.

    Then, we have Massdrop, who obviously didn't care about if the Airist board was a rip-off of something else, probably blinded by something like "uh, R2R DAC, 350$? Put it in a matching case to sell with the MassdropxCavalli amps"...of course is cheap, there're no R&D costs! (and the cheapest parts money can buy).

    Meh, after all this, paying a reputable DIYer for a Soekris based DAC makes a lot more sense, there's no BS like this to deal with.
     
  3. purr1n

    purr1n Desire for betterer is endless.

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    While it is common, or even standard practice for audio designers to take other designers' ideas and run with them, Sosolar's boards and the MD x Airist boards look essentially the same. An almost direct rip-off. We usually see this go the other direction. For example, the Matrix M-stage (Chinese amp) is a rip-off of a Lehmann Audio Linear amp, but with some minor tweaks.

    Unless Airist makes an unequivocal public statement that the RDAC was a 100% home grown product, I am inclined to give Sosolar 85-100% credit for the RDAC design. There is evidence on Chinese forums that the Sosolar boards were being used as early as 6/3/2016. That's two years ago.

    UPDATE: Also design notes on the board, iterative development, back to December 2015: http://bbs.hifidiy.net/thread-1149252-1-1.html

    Like Lehmann, Sosolar can do very little about this. I don't see copyrights, patents, or other documentation, and the dude is stuck in China. This was never a commercial product (until now). Bringing a legal case in the USA will cost money, and I'm not sure it will be worth it.

    Unless the situation can be clarified, this is bad juju (reputation-wise) for both Airist and Massdrop if they go forward.
     
    Last edited: Jun 5, 2018
  4. rshuck

    rshuck Friend

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    Yeah I'm not putting this one on MD, who at worst just turned their head the other way. I don't know about Airist's capabilities even in the slightest, so I can't even guess on if they were capable of designing this from the ground up. I'd like to know that they didn't steal the design so I'd feel better about buying one.
     
  5. Cspirou

    Cspirou They call me Sparky

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    Not only is it too close, it seems too too close.

    I'm somewhat more inclined to believe that the Sosolar guy worked with someone and they had a falling out and guy #2 just took the Gerbers with him. Someone actually reverse engineering this and creating a layout for it wouldn't really come up with a mirror image like the overlay shows.

    Even when monoprice copied Audioquest, the devices did not look the same despite using common components.

    Plus why even post internal pics if you knew you were ripping someone off. Seems pretty brazen.
     
  6. direstraitsfan98

    direstraitsfan98 D2Girls v2.0

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    Correct me if I'm wrong but isn't it common for factories in china making boards for someone to then sell their own version or a "knock off" I know of a case like this involving a polish guy who contracted a factory in china to make his boards for a retro video game romcart, he then sold those directly from his site. The designs wound up reaching hands of other places and now cheaper versions are being sold.

    One of the biggest differentiating factors between the knockoff and The real thing was that the real thing had support from the original creator, the software was significantly faster and better and had more features than the Chinese come.

    Anyway, maybe What we have here is a similar thing only this time it's airist/massdrop with the knockoff with the surpeior product, instead of the other way around.

    In any case I find the whole rabid expectation of drama and strife (people going -grabs popcorn- and shit) to be distasteful. What's more than likely To happen is everything will be handled professionally and maturely. @CEE TEE has always been an excellent ambassador and voice of the company. I'm sure everything is in good hands.

    That's my two cents, I wanted to post this morning but I was busy.
     
  7. purr1n

    purr1n Desire for betterer is endless.

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    LOL. I like the last two conspriacy theories: 1) One Chinaman getting pissed off at his Chinaman partner, thereby selling the secret plans to the highest bidder, or just leaking the secret plans to spite the other guy. 2) Unscrupulous China factories (or unscrupulous employees) leaking clients' designs.

    For all we know, Airist could have been just as much as victim. As for @CEE TEE, he wouldn't do this shit if he knew. And who knew? I sure didn't. I thought the prototype I saw was a Soekris board, until I saw "Airist" silkscreened on it. Not many read Chinese audio DIY forums here on a daily basis.
     
  8. roscoeiii

    roscoeiii Acquaintance

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    CEE TEE has posted that they are preparing a response...
     
  9. Bill-P

    Bill-P Level 42 Mad Wizard

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    Woke up a short while ago, texted @CEE TEE to see if I could come over and crash his peace, then found out this thread already did that. LOL

    Anyway, I'd give CEE TEE and Massdrop the benefit of the doubt here as I know him very well and it's very uncharacteristic of him to proceed with something like this if he knew better. Let's wait for his response.

    As an aside, I heard this thing in person already, will post some impressions on it.

    ---------------

    Edit: as an aside, makes me wonder how the "original" DAC from 2016 never caught on despite the positive feedback the RDAC has gotten. Hm........ some food for thought there.
     
    Last edited: Jun 5, 2018
  10. willsw

    willsw Friend

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    I had heard of it a while ago when it was mentioned on Head-Case and added it to my alert list. Surprisingly, there are no listings recorded by hifishark of anyone ever selling a board or a completed DAC on any of the websites it monitors.

    Maybe Sosolar just didn't push it and it never made it out of those couple Chinese forum threads.

    Maybe it really needed those two resistors Airist added.
     
  11. Cspirou

    Cspirou They call me Sparky

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    That's the sort of behavior you hear from patent trolls. Sit on something until it gets big and then extract your pound of flesh.
     
  12. soekris

    soekris MOT - Soekris Engineering

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    Nothing to do with patent trolls, they never have anything real to show.... More like it's a big step from prototypes / diy boards to full products, especially for a single guy, I know that very well....
     
  13. Dissentia

    Dissentia Rando

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    https://www.massdrop.com/buy/massdrop-x-airist-audio-r-2r-dac/talk/2099406

    From William Tse, founder of Airist Audio:

    "@sosolar I was not aware of your project until you posted here. We have been working on the R-2R DAC for a few years, and we demonstrated one when we had our first show, a New York area head-fi meetup in 2015. I have spoken to my team and they assure me that they did not copy your design.

    Our DAC is a sign-magnitude R-2R ladder, and both of these are well established and standard concepts. While other designs have implemented interesting methods such as auxiliary ladders and other compensation techniques, we stuck with the basic R-2R structure. This leads to the four resistor ladders followed by current amplifiers for each ladder and differential amplifiers to merge the positive and negative halves of each channel and apply some filtering to further mitigate the high frequency switching artifacts. None of these are novel or proprietary art. As several comments have pointed out, there are only so many ways to optimize the layout of a resistor ladder, hence the similarity between many different products. I've attached an image to illustrate those similarities:
    [​IMG]
    From left to right: RDAC, Soekris, Hibiki, Denafrips, Rockna

    Though the chips may appear similar, programmable logic devices are simply vessels and it is the code they contain that defines their operation. The control logic for the ladder is code I wrote myself based on the concept of sign-magnitude conversion. Once flashed into the chip, the code cannot be retrieved.

    By the nature of R-2R ladders, the performance of the DAC is significantly affected by the stability of the reference voltage. The two circuit blocks next to our logic device are linear series voltage regulators, using an LT6656 precision voltage reference.

    For anyone interested, here is a quick read on this type of regulator with diagrams: https://www.eetimes.com/document.asp?doc_id=1272466

    And one with a little more detail and background: http://www.onmyphd.com/?p=voltage.regulators.linear.series

    Although it is the most visible, the top board is not the only part of the RDAC. DACs using the same delta-sigma chip are not all the same, nor are DACs using the same basic R-2R topology the same. From the side angle photos of the RDAC you can see some of the circuitry underneath for handling the power, digital input selection and decoding, as well as our digital signal processing and clocking mechanisms, etc. These circuits define the RDAC as much if not more than the top board, both in terms of sound signature and design time and effort."
     
  14. purr1n

    purr1n Desire for betterer is endless.

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    It's true. None of this stuff is novel or priorietary. I guess the exact same layout on board 1 and board 3 (left to right) is due to pure coincidence.

    P.S. I'm buying the RDAC anyway when it hits production. Don't have time to sort out mysteries between Chinese people. Nothing against Chinese people most of my own DNA is "Han" Chinese. Just know how it gets with this stuff. Life is too short. Just going to enjoy the RDAC.
     
    Last edited: Jun 5, 2018
  15. JustAnotherRando

    JustAnotherRando My other bike is a Ferrari

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    The response from Airist is completely disingenuous and sidesteps the boards not sharing "similarity" but being fully transposable.

    William Tse is credited as being the designer of this board, yet he has to check with his "design team" that the design wasn't copied from somewhere else? On top of this, the company having no prior record of DAC design, a 'board'' that has no audio design in their bios, and releasing a first product as a 2000k amp that was rapidly shifted down below 1000 (even before turning up on Massdrop with economy of scale reasons) was not a credible starting position.

    If Massdrop goes ahead with this, I will be deeply disappointed with them.



    Edit: He's not credited as designer, rather as the founder of Airist. My mistake. I can't figure out how to do strike through text to correct the above.
     
    Last edited: Jun 5, 2018
  16. purr1n

    purr1n Desire for betterer is endless.

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    My crystal ball says that Airist outsourced a part of this design to some dudes in China. These dudes in China then ripped off Sosolar. Seriously, there are outfits in China that will reverse engineer shit and then make it for you. Some are quite good at it. It's all 100% legal if Sosolar had no IP or patents on his design.

    I'm inclined to believe Mr. Tse if he says he has never heard of Sosolar before. It's just a super unfortunate situation and rather embarrassing for him.

    I'm buying the production RDAC anyway. Many other people are going to buy it too. All this drama has brought more attention to the product. It's cheap, it sounds good, it's R2R. Sosolar indicated on the Chinese boards a few years ago that THD wouldn't be better than -80db anyway, so fine, it measures good enough.
     
  17. JustAnotherRando

    JustAnotherRando My other bike is a Ferrari

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    In this case, "part of this design" seems to be the essential heart. We're not talking interchangeable power supplies or casing. Which means that even if Airist is unknowingly copying someone else, they are still presenting themselves as something they are not (audio designers rather than a marketing shell). This company seems to combine some of the worst aspects of Chinese copycat culture and Western business school fluff.

    I live close to the centre of copycat culture, and usually find it amusing. I buy fake Lego, and own a fake Dyson fan*, bought for curiosity and laughs, and because real Dyson fans cost some insane amount of money that I would never pay for a fan. Personally though, a DAC is not something that will impact the well being of my family, and to me higher end audio gear is a non-necessary luxury that combines geeky curiosity with hedonistic reward. I'd been intending to join the drop for similar reasons (not much money, it's R2R and new) but I'd prefer to support companies run by people genuinely passionate about developing audio rather than people more concerned with regurgitating their completely irrelevant Ivy League** bios.

    But Airist to me is more the entertaining sideshow here. I am much more interested in how Massdrop responds to this.



    * It's more a semi-fake, it uses the same aerofoil tech but doesn't look anything like a Dyson

    ** Nothing wrong with Ivy League bios, half my American in-laws have them. Weird multi-tiered tertiary education system over in the US though.
     
    Last edited: Jun 5, 2018
  18. soekris

    soekris MOT - Soekris Engineering

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    One thing is patents, nothing is really covered by non expired patents in a basic Sign Magnitude discrete R-2R DAC.
    But another thing is copyright, I would say that the designer / thief of the Airist DAC violate copyright by that direct rip off, no way can they be that close by coincidence.... I would be pissed too if somebody copied one of my designs.
     
  19. purr1n

    purr1n Desire for betterer is endless.

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    You mean the Google-Fu on linear series voltage regulator parts didn't convince you?
     
  20. monacelli

    monacelli Friend

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    Compelling as this product may be, there isn't a snowball's chance in hell I would buy one if the goofballs from "Airist Audio" are going to be receiving a cut of the earnings. If I were Massdrop, I'd drop the Airist team like a hot rock and forget I ever knew them. Maybe they could work with Sosolar and release a Massdrop Hibiki DAC? It would probably sound better anyway since he actually has some idea what the fuck he's doing. I was just kind of warming up to the Massdrop business model (the Plus looks great), but if they're cool with doing business like this, I'm not interested in being a customer.
     

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