Yet another r2r dac

[randytsuch]

Massdrop is offering an R2R dac

https://www.massdrop.com/buy/massdrop-x ... o-r-2r-dac
https://www.head-fi.org/threads/massdro ... 50.881315/

Normally, I would not have mentioned it.
But if you search in the massdrop comments, and the head fi thread for posts by sosolar, you'll find that it appears the massdrop company that developed this dac (airtist) copied the layout from sosolar. It has made this drop more interesting than usual, and is probably killing alot of interest.

I'm hoping sosolar starts to offer his dac somewhere other than taobao, or we can order some boards from taobao and give them a try?
https://world.taobao.com/item/525195615 ... 3.2.4SmcUz

Randy

[nige2000]

whats the story in regards digital filters and oversampling?
is this another sign magnitude dac?
the massdrop seems decent value
6 month wait is quite a while
certainly looks like a very moddable dac

[randytsuch]

Copied from head fi thread, by sosolar
Hi there, I am original author of hibiki r2r.
We have done so much version of that board, and sell them on taobao. There is no question why they get our board.
The point is, we spent 3 years on developing on r2r, and finally got that verion.
The first one is not sign-magnitude architecture showed on Wenzhou small exhibition.
The second verison is still non sign-magnitude, but uograded sulzer-like regulator(i.e. ref+op+buf), that sound quite good already, showed on Shenzhen small hifi-show.
The third version is a huge change that import true sign-magnitude arch, with splited ground plane(i.e. left and right when decoding, and join them at next stage which can prevent some high freq noise) and even more auiet power supply(we tested it is well below -110db@100hz, -140db@1k and further).
The fourth version is just adding the led to show working condition.

In analog LPF part, there are variant version of combination, very interesting.
Version1 is 5534 for buffer, impedence is much lower that wont affect the performance(freq cornor) of next lpf stage. The second stage is NJM2114 for two channel's filtering. Finally, a LT1128 for signal combining(because sign-magnitude has a hugh problem that its output is containing DC of 1/2 VCC, we must get rid of it) and also act as a lpf. All two stage of lpf is bessel-like LPF with 40k cut-off. This is the version for sell.
Version2 is BUF634 + NJM2114 + AD797 with 80k cut-off. (Please believe your eye, 80k sounds 3 way better than that with 20k bandwidth)
Version3 is my favourite version NJM5534 + NJM2114 + AD8597 with 80k cut-off. Accurate, fast, emotional.

In my original design, we use silmic2 for 'board power tank', as it produces quite nice sound stage.

Feel free ask me more detail about this arch including phase splitter as well as CPLD decoding part. Because I dont think they will provide any more detail than me.



Later post by sosolar
Some of my customer have done so much expriment on it, says Li-on power supply, direct transformer output bypassing opamps, insanely pricy silver foils capacitor, metal-can OpAmps, LPF alterations, reclokings, better isolations....so much creative ideas. All of them are enjoying DIY.
That exactly is the scene we want to see.



That's pretty much all I know about it
Randy

[nige2000]

i seem to have read the headfi thread and missed that
well its no digital filter if there using lpf
is it the sign magnitude (last)version there selling on taobao?
yea it could be interesting

[randytsuch]

Yeah, I'm pretty certain its the sign mag version that is sold on taobao.

Sosolar actually posted that people should wait though, he's coming out with a balanced version soon.

Hopefully we can get his attention over here, and then you can ask him questions directly.

I was interested in the massdrop dac when I first read about it, but after seeing how they copied the pwb layout, and their responses when it was pointed out, I'm probably going to pass on it.

Randy

[abraxalito]

Very interesting story for sure, I've been following along as its unfolded.

What I notice is different from the way Soekris does it is that they're not using *8 drivers for the resistors (like HC595, can't recall which particular device he's using), but individual (SOT23-6) devices, presumably one per resistor driven. This reminds me rather of dCS who in one upgrade to their series of DACs went from using chips with multiple drivers per device, to individual drivers.

I agree with Randy, the responses of the founder of Airist left a none-too-pleasant taste in my mouth. Last time I looked he still couldn't bring himself to admit his hired contractor had reverse-engineered sosolar's board.

[nige2000]

id doubt this design copying will stop the masses from buying from massdrop
diyers will be more empathetic with the original designer but theyll be in the minority

its pricey enough just for the board compared to soekris 1021?

[randytsuch]

id doubt this design copying will stop the masses from buying from massdrop
diyers will be more empathetic with the original designer but theyll be in the minority

its pricey enough just for the board compared to soekris 1021?

Yen and Yuan use the same symbol, and I was confused about the price.
At 2000 Yuan, price is too high for this board to make sense.

Well, I guess I'll just watch the ongoing massdrop soap opera lol.

Randy

[jkeny]

id doubt this design copying will stop the masses from buying from massdrop
diyers will be more empathetic with the original designer but theyll be in the minority

its pricey enough just for the board compared to soekris 1021?

Yea, compared to Soekris, it doesn't seem to make sense for any reason either financial or technical or am I missing something?

[randytsuch]

Yea, compared to Soekris, it doesn't seem to make sense for any reason either financial or technical or am I missing something?

Conversion mistake on my part, moving a decimal just a little makes a difference. ;)

On another forum, sosolar was talking about something like $1500 for a balanced version, seems high but we shall see.

Randy