[rb2013]

  Nice find!
 
I am quite interested in a modern R2R DAC that is cheaper than the TotalDAC.
 
The company is Soekris Engineering (www.soekris.com) located in Scotts Valley, California
Nothing on their webpage as of yet.
 
The funny thing is that is the same company that made one of my Embedded x86  Firewall Single Board Computers, this explains the nice layout of the board.

That TotalDAC is some machine - hand soldered individual resistors!  Audio-gd makes some nice DACs - like the 10.32 Ref
 
http://www.audio-gd.com/Pro/Headphoneamp/Reference10/RE10EN.htm

 

[rb2013]

Over on another thread - someone asked - Why not just run a spdif optical out from the PC -it sounds really good?  Why go for a separate UBS interface.
 
My response was this:
"Really, Optical in every implementation has sounded worse to me.  But Optical SPDIF are you running straight out of the PC card or laptop?
 
In that case the PC has to do three functions: 1)convert bits to a digital stream, like (WAVE, FLAC, DSD, MP3, etc).  (2) Then convert that stream to the appropriate output format for the DAC to lock onto - say PCM.  (3)Then convert that electrical signal to light pulses.  The DAC then has to reconvert those light pulses back into electrical signals and then convert those digital electrical signals into analogue wave forms to send to the pre-amp.  All in Realtime.  With USB Asyn 2.0 the digital output is kept in the OS digital domain, using different standards or protocols (for example in Windows) like ASIO, KS (Kernal Streaming), WASAPI, DS, etc.. The best like ASIO and KS bypass the Windows mixer and on chip sound processing, passing a 'pure' digital stream to the interface processor which then converts to PCM or DSD, here the interface can output this signal in either optical or electrical formats and transmit those over spdif, either optical or coaxial to the DAC. 
 
I've heard all the arguments about optical 'galvanic isolation' but the sound to me is closed in, almost muffled.  And I have tried some of the best optical chords, and it still sounded inferior.  The issue is the very inexpensive electro-optical/optical-electro converters on most MBs, cards, interfaces, or DACs.  But if you like optical, the Gustard has an optical output.  It comes down to clocking, jitter management, and ps filtering - all things the Gustard does extremely well.
 
Dedicated dual 0.1ppm Temperature Compensated Crystal Oscillator Clocks in the Gustard U12.  Rather using one clock and the realtime errors prone to converting the math, the Gustard uses a dedicated high speed clock for each frequency. 
 
"
 
I guess the issue is asking a lot of the PC - especially within a very electrically noisy environment.  The switching PS, fan motors, all feed back through the powers supply creating ps ripple and interference issues as well as the EMI/RFI of the CPU and associated components.
 
Any comments?  How does your Gustard compare to running straight from the PC?
 
Edit PS anybody directly compare the U12 to the Gen2 board on the Schiit Bifrost?  I thought someone mentioned that they had that setup

 

[rb2013]

Someone also asked about issues with the C-Media CM6631A
 
 
"This is based on the newest USB2 audio chip on the block, The C-Media chip is the CM6631A. This version in turn is the newer, the “A” version of the CM6631 chip which has been implemented in several recent products. The CM6631A differs from the more common (and older) CM6631 in that it supports 176.4KHz sample rate. All other features are the same as the CM6631."
 
 
"Since the board does not switch the clock lines, you can only select one of the clock lines to feed the ESS DAC. In this manner, with some of the sample frequencies the DAC will operate in synchronous mode and with other sample frequencies, in the normal asynchronous mode.
For example, if you chose to use the X45 line (45.1584 MHz) as the clock for the ESS DAC, then when playing 44.1K, 88.2K and 176.4K the DAC will operate in synchronous mode and when playing 48K, 96K and 192K, the DAC will operate in asynchronous mode.
You could manually switch the clock lines but this is not only impractical, but it could also upset the DAC requiring a reset."
 
 
 
 
https://hifiduino.wordpress.com/2013/04/03/c-media-cm6631a-based-usb-i2s-interface/

 

[rb2013]

Someone also posted this link to Jason of Schitt's comments about his discussions with Mike Moffat about USB audio:
 
http://www.head-fi.org/t/701900/schiit-happened-the-story-of-the-worlds-most-improbable-start-up/690#post_10441924
 

  When Mike Says USB Sucks, You Listen
 
Okay. Enough of the bragging. The fact is, I’m excited to have Mike Moffat as a partner, and I’m proud of his resume. He’s contributed quite a bit to the digital audio realm—just look at Sony’s original stance of “perfect sound forever,” and their current frank discussion of jitter-reducing measures in their audio products. Quite a turnaround.
 
But to get back on topic, let’s talk about DACs. Not Mike’s original idea for a DAC, the one he came up with shortly after we started the company, but Bifrost....
 

  Mike grumbled something under his breath, then spat out: “But USB sucks. It just sucks. It was never meant for audio. It’s an all-purpose, packet-based grab-bag that might be fine for printers or hard drives, but it’s just crap for streaming. You can recover the clock from the packet clock, barf, or you can have the computer and DAC do some negotiating and guess at the clock, barf, or you can turn the whole car around and drive it from the back seat with the computer providing the clock, barf.”
 
Note: the above, for the more technical, is Mike’s take on isosynchronus, adaptive, and asynchronous USB implementations.
 

Well I've had some really good cd spinners, dedicated transports, and a very expensive near sota analog system.  And I don't remember getting the quality of sound as I'm hearing now with the Gustard.  

 

[ThurstonX]

  Someone also asked about issues with the C-Media CM6631A
 
"This is based on the newest USB2 audio chip on the block, The C-Media chip is the CM6631A. This version in turn is the newer, the “A” version of the CM6631 chip which has been implemented in several recent products. The CM6631A differs from the more common (and older) CM6631 in that it supports 176.4KHz sample rate. All other features are the same as the CM6631."
 
"Since the board does not switch the clock lines, you can only select one of the clock lines to feed the ESS DAC. In this manner, with some of the sample frequencies the DAC will operate in synchronous mode and with other sample frequencies, in the normal asynchronous mode.
For example, if you chose to use the X45 line (45.1584 MHz) as the clock for the ESS DAC, then when playing 44.1K, 88.2K and 176.4K the DAC will operate in synchronous mode and when playing 48K, 96K and 192K, the DAC will operate in asynchronous mode.
You could manually switch the clock lines but this is not only impractical, but it could also upset the DAC requiring a reset."
https://hifiduino.wordpress.com/2013/04/03/c-media-cm6631a-based-usb-i2s-interface/

 
If I'm not mistaken, those comments refer to the specific board in question (i.e., implementation of the C-Media CM6631A).  It would be interesting to put those issues to Jason and/or Mike to see if they apply to the Gen 2 USB module in the Bifrost.  In reading Jason's story of the Bifrost's development, he mentions the "click" associated with a reset that takes place when switching between bit depth/sample rate in order to keep everything bitperfect (i.e., no upsampling).
 
The following come from  http://www.head-fi.org/t/701900/schiit-happened-the-story-of-the-worlds-most-improbable-start-up/690#post_10441924
 
“No, I’m not gonna tell you that,” I said. “But what are we talking about here? How hard is it to keep everything bitperfect?”
 
“It’s a pain in the ass,” Mike said. “We’ll need a microprocessor to switch the clocks, we have to reset the DAC when sample rates change, we’ll need a hard relay mute, stuff like that.”
 
...[and later]...
 
Rewards of doing what everyone else was doing:
 
...

1. Easier support: no explanations about why the DAC has to be reset, resulting in the famous “clicking)

 
 
Who knows, maybe $155 dollars will fall into my lap (or I'll just get way too curious), and I'll get to compare the Gustard U12 to the Gen 2 USB Bifrost.
Thanks for all the posts, Bob 

 

[rb2013]

ThurstonX  Didn't know if you saw these posts:

  I have also ordered a Gustard U12, arrived 3 days ago from China
It sounds brilliant, bass became somewhat more elemental while the mids and highs are now more detailed
I can only recommend it!
 
notes: I have replaced a CM6631A based USB powered Chinese board (which also sounded way better than the on-board SPDIF out of my PC) with the Gustard
IMHO both the CM6631A and the Gustard U12 sound much better than the Nuforce U192S (I had that one before the CM6631A)

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1. sandab
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Got my Gustard U12 today, and it sounds excellent.  Much better device than the Peachtree X1.  The X1 by itself sounded pretty harsh with distorted highs and was unlistenable to me without a Wyrd.  Clearly the USB +5V noise was beyond it and affected its PLL badly.  Swapping out the X1 for the U12 helped smooth out and clean up the sound substantially, and although I can tell on any recording it's most noticeable on really bad ones (think Amy Winehouse / Back in Black).  When I have time I'm going to try it with only the U12 and no Wyrd.  But between the X1 and U12 there's no question which is better spent money...

 

 

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Mine arrived today and the smile cannot be wiped from my face. I always had my skepticism about reclockers but 0.1PPM made me sit up and take notice.

No bloom, No glare, smooth passage into the ear canal without any harsh ringing.

My recommendation is to buy it now before the price sky rockets and buy shares in Gustard!

 

[sandab]

Received my balanced 110ohm AES/EBU balanced coax (Canare cable, Neutrik XLR connectors, nothing fancy here) the other day and today did a little bit of swapping back-and-forth with a 75ohm RCA coax, and I don't think there's any obvious difference.  Possibly some very slight difference in the high mid quality; it might be slightly cleaner but I wouldn't sign off on this.  I tested mostly with the new Bennet-Gaga release in 96/24 and think Gaga's vocals might be a little cleaner.  This is between a U12 and a Yulong Sabre D18; I think the DAC is a pretty significant factor here - it's in fact the DAC that doesn't benefit significantly from the balanced digital input.  Regardless, I like XLR connectors better than RCA so it's a keeper if for no other reason.

 

[Jamiee]

I use both AES and SPDIF COAX outs on the U12.
 
The AES feeds an April Music DAC, which in turn feeds two headphone amps.
The SPDIF COAX feeds a KRK ERGO controller, which in turn feeds a pair of Focal studio monitors and sub.

 

[NinjaHamster]

How much power does the Gustard require ?  Is it a 12V input, and how may mAh ? I'm just trying to figure out if my linear power supply could run it.  Thankyou.

 

[Jamiee]

The U12 has a 115v or 220V IEC socket for power.  This is switchable inside the unit.

 

[rb2013]

  How much power does the Gustard require ?  Is it a 12V input, and how may mAh ? I'm just trying to figure out if my linear power supply could run it.  Thankyou.

Yes this is one of the few USB interfaces that run on regular AC - not DC.  
 
Just ordered this cable for it: Venom 3s C13 Powersnakes Shielded Power Cable - 1.75m
 
http://www.hideflifestyle.com/venom-3s-powersnakes-shielded-power-cable-1-75m.html
 
Such a fine unit deserves to be well fed. 

 

[rb2013]

 
The independent power supply helps a lot because it is no longer dependent on the weak and noisy USB 5V supply, which can only supply up to 500mA of current, that can drop to 100mA in some cases.
 
If you are interested in a better power supply consider replacing the power transformer, I have a similar unit based on the previous generation XMOS and it came with the green Bingzi transformer. I wanted something that was UL rated and replaced it with an Amgis/Alfamag, the bonus was it ran much cooler and the Alfamag was about 10% heavier (more copper in the windings)
Outside of the US, Talema is easier to find and a little cheaper.
 
I also installed ultra low jitter crystal XOs replacing the "Precision 0.1ppm" ones that it came with.
The Gustard looks like it has separate regulators for the XOs so it is probably worthwhile to put in a low jitter unit.
 
The last part is to replace some of the caps with Panasonic OSCONs and Nichicon FP Polymer caps.
The main rectifier filters  I used the Chemicon KZN. The KZN has 2x lower ESR than the supposedly Panasonic PX caps
(I think the PX are fakes)
 
Pictures of my unit.

 

Just ordered the Alfamag transformer - $17.68 from Digikey it looks like a drop in replacement - thanks for the info!
 
Edit: Do you think the pinouts are the same on both the stock and Amgis trannys?  It [size=13.3333330154419px]appears so except sideways.[/size]  The Amgis is  115VAC on the top - 7VDC on the bottom.  Looking down neg on the left - pos on the right. The stock is looking down 115V on the left - but looks like 9V on the right.  Is that Neg to the left on the DC - the AC to the right?  Wondering if I might need a 9V version?
 
It looks like these might be better in this unit - both 9V http://www.digikey.com/product-detail/en/L01-6341/TE2245-ND/2137075
http://www.digikey.com/product-detail/en/70041K/1295-1041-ND/3881432   The Amgis is $19 and the Talema is $22.
 

 
Also the caps to the right of the FCs the metal cans look like 16V 330uf (C55 & C56) - what do you think?  Will replace with Oscons. The stock ones have a little black box SMD on the bottom, those are the polymers?  
Digikey has the through the hole Nichicon FP's http://www.digikey.com/product-detail/en/RHT1C331MDN1/493-3739-ND/2207349 
 

 

[Jamiee]

 
Just ordered this cable for it: Venom 3s C13 Powersnakes Shielded Power Cable - 1.75m
 
http://www.hideflifestyle.com/venom-3s-powersnakes-shielded-power-cable-1-75m.html
 
Such a fine unit deserves to be well fed. 

 
Yeah I'm running mine with a PS Audio AC-5 PC.
Overkill?... Yeah probably, but what the heck!  

 

 

[rb2013]

   
Yeah I'm running mine with a PS Audio AC-5 PC.
Overkill?... Yeah probably, but what the heck!  

 

+1  Did it make a difference?

 

[Jamiee]

Couldn't tell you with the U12 as I was already using the AC5 with the U10 and just swapped it with the 12 when it arrived.
 
That said, I haven't met a single piece of equipment yet that hasn't been improved with the use of a good quality PC.
99% of my system is powered through PS Audio AC12's, 10's, or 5's.