Massdrop x Airist Audio R-2R DAC: A Discrete Resistor Ladder DAC For $350
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wushuliu

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Unless someone has a stake in MD or the RDAC (read: MD shareholders or sosolar), not sure why anyone would get so hot and bothered on this forum, especially over reviews. Seriously, go outside; go on a date. There's gotta be something more productive than venting over a product that you're not going to buy anyway. If fighting corruption and dishonesty is your thing, run for local office or something. Or you know, keep typing away furiously on HF, whatev...

Still interested in users sharing their knowledge and experiences with sound if any one still wants to discuss that.
TL'DR: So what if someone did something dishonest you should take a stand on. Go get a burger or something.

Lol, I don't even know where to begin with this statement. By all means please out yourselves as being on board with this...
 
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Raphael DeLaGhetto

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TL'DR: So what if someone did something dishonest you should take a stand on. Go get a burger or something.

Lol, I don't even know where to begin with this statement. By all means please out yourselves as being on board with this...
You're proving his point with a post like this. From what I can tell sosolar didn't protect himself because he neglected to file a patent in addition to putting his design into the public domain. Whether that makes Airist wrong for using it or you're upset that he didn't credit sosolar - virtue signaling & grandstanding on a message board will do absolutely nothing to fix this issue. None of you are moving the needle with this type of discourse. At all.

I'm so sick of getting alerts about this thread & it's another person wagging their fingers sneering tisk tisk at people who decided to buy it. Your judgments are irrelevant to the 200+ people who have already bought it. If you aren't going to, fine. If you are, fine. But this whole holier than thou mess has run its course. If it bothers you that much then go on MD & bombard them with emails. Stop filling this thread with this drivel. Put your headphones on, listen to music, and chill out with the rest of us.
 
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project86

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You said you are a paid reviewer. Why would a "paid reviewer" write negative about another product looked as "possible competition"? Simple answer is; to make the sponsor happy.
Professional reviewers aren't informative anymore and I dont blame you, Money Talks but losing objectivity is misinformative. :wink:
I still don't think you understand the way things work. A "paid reviewer" gets paid by the outlet they write for. In my case, InnerFidelity and Darko.Audio. So when I review, say, an Audio GD product on either site, I'm not paid by Audio GD. I'm paid by the owner of the site. See the difference there? It's an important distinction.

Those endeavors are completely separate from my reviews and general participation on this forum, from which I derive zero income. HeadFi itself has "sponsors" but I benefit as much from their sponsorship as you do, which is to say - not at all. I can say whatever I want in terms of loving or hating a product from any brand. Just like you can.


If you had a friend who got paid by his or her local newspaper to handle their movie review column, would you then discount any opinions s/he gave whilst discussing movies over lunch? Or how about someone who writes for a tech blog, covering phones and tablets etc.... if they also mentioned their thoughts elsewhere on, say, Reddit, would you discount them as being "paid reviewers" and therefore irrelevant?

I'd say no. Their opinion carries much, or little, weight based on the quality of their work and my history of agreeing/disagreeing with it. That's all.

In any case, I think Massdrop has an uphill battle on their hands unless they stop posturing and simply begin an honest dialogue with @sosolar. I respect @CEETEE and appreciate what he's done for the community within the scope of his job as Massdrop, but that doesn't make him infallible. Same goes for Will Bright and anyone else involved in the company. Can they legally continue with this drop? Very likely. But should they? That's the real question.
 
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Nickol

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Too bad you have no clue what you are talking about.
I think that I am not far from the truth. I do not care from whom you get money for reviews, but you get them in the end (not so important who is behind it). Therefore, it is difficult to say that you are objective.
 
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pietcux

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Can someone enlighten why I should, legal questions aside, prefer this dac over a Schiit Bifrost multibit?
 
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project86

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I think that I am not far from the truth. I do not care from whom you get money for reviews, but you get them in the end (not so important who is behind it). Therefore, it is difficult to say that you are objective.
Got it - in your world, a professional food/book/film/etc critic can never be objective, and their opinions are not to be trusted. Even while discussing their topic "off the clock" in another context or venue. So a friend who has driven and evaluated hundreds of cars for a magazine like Road & Track is NOT someone you would go to for advise on your next purchase. Because, you know, he gets paid to do that.

This all seems totally logical to me.

Can someone enlighten why I should, legal questions aside, prefer this dac over a Schiit Bifrost multibit?
I had a Bifrost Multibit in my system just prior to getting the RDAC in for evaluation. Unfortunately their paths did not cross to allow for direct comparison. From memory, I'd say the two were fairly close in terms general resolution. The RDAC strikes me as the more "pure" sounding component, and has what I'd say was more convincingly lifelike treble. The Schiit might do low-end kick a little better, but for me the treble seals the deal in favor of the RDAC. That said, I could easily build a system around the Bifrost MB where the RDAC would be a step down.
 
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gLer

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In any case, that's the model I (intensely) disliked, and I was not alone in that. I do have a hard time believing Kingwa has somehow transformed it into a vastly better product, with a headphone amp, for half the price. But I could be wrong as I've never heard the R2R-11.
Hi @project86. It was not my intention to offend, nor cast aspersions on your credibility, so if my comments did so in any way, I wholeheartedly apologise.

It was also wrong of me to assume you were referring to the R2R-11, although in my defense that’s the only Audio-Gd R2R dac/amp I was aware of at this price point. I’ve never used or heard the Singularity 19 so can’t comment. I have very much heard (and use) the R2R-11, which I consider the best dac I’ve heard to date at any price (admittedly not having heard too many $1000+ dacs. Still, no matter how much I like it, I accept others may not, so again if my defense of my favorite dac was over eager and crossed a line, my apologies.

In saying that I really do hope you track down and get to audition the R2R-11, for good or bad. I’d very much like your opinion on how it compares to Airist. And I dare say it’s going to surprise you! I think it’s great that MD is bringing R2R to the masses, controversy aside, and I think once people try it and like it, they’ll also appreciate what ridiculously good value the R2R-11 represents at the same price.
 
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pietcux

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Got it - in your world, a professional food/book/film/etc critic can never be objective, and their opinions are not to be trusted. Even while discussing their topic "off the clock" in another context or venue. So a friend who has driven and evaluated hundreds of cars for a magazine like Road & Track is NOT someone you would go to for advise on your next purchase. Because, you know, he gets paid to do that.

This all seems totally logical to me.



I had a Bifrost Multibit in my system just prior to getting the RDAC in for evaluation. Unfortunately their paths did not cross to allow for direct comparison. From memory, I'd say the two were fairly close in terms general resolution. The RDAC strikes me as the more "pure" sounding component, and has what I'd say was more convincingly lifelike treble. The Schiit might do low-end kick a little better, but for me the treble seals the deal in favor of the RDAC. That said, I could easily build a system around the Bifrost MB where the RDAC would be a step down.
Then all people here who have a problem with all those legal uncertainties could happily buy a Bifrost MB and call it a day, I guess. Me included. The stuff from Jason and Mike is legit, that's for sure. Just saying.
 
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MarkArtz

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Then all people here who have a problem with all those legal uncertainties could happily buy a Bifrost MB and call it a day, I guess. Me included. The stuff from Jason and Mike is legit, that's for sure. Just saying.
I do like Massdrop. The list of gear I bought from them is long, my Fostex Ebonies are one of my favorite hps. I have the Mimby and the Bifrost MB, hard to say one is better than the other. This whole legal situation makes the Bifrost MB a much better option. If anything goes negative against MD they won't be able to bring any support, if they get to ship the first batch, and thats in the best case scenario.
 
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Inorbit8

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In any case, I think Massdrop has an uphill battle on their hands unless they stop posturing and simply begin an honest dialogue with @sosolar. I respect @CEETEE and appreciate what he's done for the community within the scope of his job as Massdrop, but that doesn't make him infallible. Same goes for Will Bright and anyone else involved in the company. Can they legally continue with this drop? Very likely. But should they? That's the real question.
Couldn't have said it any better. Very disappointed at the actions that MD has taken so far.
 
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SamusAran

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TL'DR: So what if someone did something dishonest you should take a stand on. Go get a burger or something.

Lol, I don't even know where to begin with this statement. By all means please out yourselves as being on board with this...
Yeah, definitely "DR" or you would've known that I was responding to accusations against project86 for being dishonest or a sell out or whatever and not on the IP issue...
 
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WillBright

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Hey Friends,


I was hoping to avoid making another post on this topic, but given sosolar’s most recent posts, I feel it’s necessary to summarize and clarify the statements and claims made.


Sosolar surfaced in the Massdrop RDAC discussion at the beginning of the week, claiming the RDAC was a copy of his Hibiki project. A lot of people got excited by this, maybe not understanding all the details, but seeing the layouts of the PCBs looked the same, and accepting that as proof of sosolar’s claims.


Seeing that post, we (Massdrop) were surprised to see the similarities as well. We were unfamiliar with the hibiki DAC, and we didn’t play a role in the development of that top PCB, so we reached out to William at Airist. He let us know he wasn’t familiar with the project either, and was reaching out to his engineering manager to get more information (thus the post from William explaining reference designs and saying he was unfamiliar with the hibiki DAC).


At this stage, we needed to get details from the engineering manager and the contract engineers he hired to work on this project. The layouts looked the same as the RDAC, but the arrangement of some parts was different, and the spacing between parts was also different. That’s all we knew at the time. Sosolar continued to feed the discussion, making further claims, and posting details of his project on various discussion boards, talking about releasing a product and gathering feedback. At this point, I had already provided my contact information as a direct response to his comment on our discussion, and received no response.


While this was happening, we were able to speak with the engineering manager from Airist and his contract engineer. The engineer explained his process; initially he was provided with a set of specifications, a mandate for a ladder arrangement that would meet the specs of William’s overall design (the top PCB represents ~25% of the overall RDAC design). Given that mandate, he began searching for reference material, and discovered this reference design posted for free use (says that on the post) in 2014: http://bbs.hifidiy.net/forum.php?mod=viewthread&tid=994769


From the basis of this reference design, he looked for examples of layouts that could provide a good baseline, while allowing him to build the underlying structure to serve the purpose of William’s design. Important note here, PCBs have multiple layers, the top board of the RDAC has four. The top layer is where components are positioned, but the content of the other layers determine how those components interact.


At this point, the engineer found the Hibiki DAC, and while the same configuration of parts wouldn’t yield the desired result, the general layout would work for this project, so he used it as a reference and creating the RDAC top PCB layout. This is why it looks the same, and why we subsequently posted as much in our discussion. My wording could have been more direct, but it’s not an exact copy, so “inspired by” seemed like the best option, but ultimately it was more confusing than clarifying. The position of parts is nearly the same, but sosolar continued to post, accusing Airist’s team of reverse engineering the board, which isn’t the case.


From there, still having received no contact from sosolar, I reached out to the email address associated with his Massdrop account, explaining that I’d like to understand exactly what he’s saying, and to understand more about the Hibiki project in general. Now I want to pause here, and make clear an important understanding in professional communication. Emails are intended for the specified recipients, and it’s bad form to break that trust. I won’t be posting screenshots or exact wording from his message, but following sosolar’s most recent posts I feel it’s important to share some of the general themes in our communication.


He responded to my messaging with a development timeline for the Hibiki DAC, starting in June 2015 and ending in July 2016, and demanded that we post a comparable timeline for RDAC development. His timeline had great detail, with lots of links to posts and things of that nature, which makes sense given the Hibiki was developed publicly, with sosolar sharing details with the hifidiy.net community. It’d be nice if posting a timeline would answer the questions at hand, but the RDAC development was private, there are no public posts to verify the statement. Given the many responses from people saying they didn’t believe our previous statements, I didn’t think an unverifiable timeline would answer questions for anybody.


The most important part of Sosolar’s response, was around some parts in the design he said were unnecessary, essentially saying they were stylistic choices on his part, that wouldn’t exist on another board unless the functionality was being copied through a reverse engineering service.


All of these parts which are unnecessary for the HIbiki, but are critical to the function of the RDAC. We answered all of Sosolar’s questions directly, here is the explanation we provided for each of the sections sosolar called out:


For the op amps:


The op amps on the RDAC top board are not just buffers, they are necessary for the operation of a sign-magnitude ladder. The output from a network of so many resistors is very weak, so we have to bring that signal strength up or else further processing will drown it in noise. These op amps do that amplifying, merge the outputs from the positive and negative ladders into one output waveform, and filter out the switching artifacts.


For the large transistors:


Because the R-2R ladder is basically a 48 resistor network on each side, you need a fair amount of current to actually drive the whole thing, not to mention extra overhead.


For the logic switches:


These are the same switches used in the open source schematic posted in 2014, and that is how the engineer picked this part.


Sosolar’s response to this message said that he was waiting for us to post the timeline, followed by a sentence that I think was trying to suggest he wasn’t accusing Airist of reverse engineering and copying the DAC design, but the layout alone (not trying to knock his english, I don’t write a character of chinese, but I couldn’t understand his wording) which would be a change from his previous statements, but I can’t be sure. Hopefully we can talk about this on the phone where mandarin/cantonese speaking team members can remove the language barrier in this technical discussion.


I responded to his message early this morning, hoping to catch him still awake so we could have a call, and in that email I proposed a solution that would give clarity to the community. We could both provide our gerber files to an unbiased third party (I suggested the new editor of IF, guy has no skin in this, and I’ve been asking folks for his contact info today in an effort to reach out and see if he could do this), they can examine the files and tell the community if the RDAC top pcb is a copy of the Hibiki pcb. I haven’t received a response from sosolar, but it’ll be morning in China soon, so hopefully sosolar is game for what seems like a pretty amenable situation.


TL;DR


Overall the layout of parts on the hibiki DAC and the top board of the RDAC are nearly the same. Neither Massdrop or William Tse of Airist was aware of the Hibiki DAC before sosolar’s post on Massdrop. The layout is not 1:1, but it’s clearly close enough where folks feel it’s essentially 1:1. We’ve explained how the hibiki layout was used by Airist’s contract engineer, and hats off to sosolar for creating a layout that works for the RDAC’s execution needs. If he had interest in compensation for this, he has plenty of avenues available to express that, as it stands, it seems he’s more interested in posting about the balanced hibiki he’s releasing this August. The similarities end at that top layer, and we’re glad to provide RDAC files for verification by an unbiased third party.


We’re doing everything we can to resolve this amicably, and we’ll keep trying, hopefully sosolar will engage with us.
 
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While this was happening, we were able to speak with the engineering manager from Airist and his contract engineer. The engineer explained his process; initially he was provided with a set of specifications, a mandate for a ladder arrangement that would meet the specs of William’s overall design (the top PCB represents ~25% of the overall RDAC design). Given that mandate, he began searching for reference material, and discovered this reference design posted for free use (says that on the post) in 2014: http://bbs.hifidiy.net/forum.php?mod=viewthread&tid=994769

From the basis of this reference design, he looked for examples of layouts that could provide a good baseline, while allowing him to build the underlying structure to serve the purpose of William’s design. Important note here, PCBs have multiple layers, the top board of the RDAC has four. The top layer is where components are positioned, but the content of the other layers determine how those components interact.

At this point, the engineer found the Hibiki DAC, and while the same configuration of parts wouldn’t yield the desired result, the general layout would work for this project, so he used it as a reference and creating the RDAC top PCB layout. This is why it looks the same, and why we subsequently posted as much in our discussion. My wording could have been more direct, but it’s not an exact copy, so “inspired by” seemed like the best option, but ultimately it was more confusing than clarifying. The position of parts is nearly the same, but sosolar continued to post, accusing Airist’s team of reverse engineering the board, which isn’t the case.
Thank you for researching and publishing this! To me, this seems plausible and believable (though I'm not an electrical engineer, I should add). I could imagine that there's still some room for tuning in that layout for someone talented, so it's a bit sad that there was no drive to make this part of it more unique simply by improving on it, but it sounds like both DACs have some shared history anyway. Maybe @sosolar can comment on whether he was aware of the reference material on hifidiy.net that you mentioned.

We could both provide our gerber files to an unbiased third party (I suggested the new editor of IF, guy has no skin in this, and I’ve been asking folks for his contact info today in an effort to reach out and see if he could do this), they can examine the files and tell the community if the RDAC top pcb is a copy of the Hibiki pcb. I haven’t received a response from sosolar, but it’ll be morning in China soon, so hopefully sosolar is game for what seems like a pretty amenable situation.
While I'm inclined to believe you, this would be a very welcome step to resolve this as far as I am concerned.

Overall the layout of parts on the hibiki DAC and the top board of the RDAC are nearly the same. Neither Massdrop or William Tse of Airist was aware of the Hibiki DAC before sosolar’s post on Massdrop. The layout is not 1:1, but it’s clearly close enough where folks feel it’s essentially 1:1. We’ve explained how the hibiki layout was used by Airist’s contract engineer, and hats off to sosolar for creating a layout that works for the RDAC’s execution needs. If he had interest in compensation for this, he has plenty of avenues available to express that, as it stands, it seems he’s more interested in posting about the balanced hibiki he’s releasing this August. The similarities end at that top layer, and we’re glad to provide RDAC files for verification by an unbiased third party.
Maybe there could be a collaboration between Massdrop and sosolar on that one, especially given how many Massdrop members expressed disappointment about the RDAC being single ended. I imagine that would be advantageous to both parties, and a nice outcome of this debacle.
 
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Ricey20

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Thanks for the response Will. MassDrop should have been more transparent about this since the beginning, instead of the responses that seemed like they were side stepping the issue or dismissing it completely. It all makes sense though and it seems to be the fault of Airist's contract engineer. They should have detailed to their superior or project manager about using existing designs and influences and asked for permission to proceed. It would be great if MassDrop/Airist bring on sosolar as a contract engineer for a balanced version later.
 
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