USB audio transmission isn’t bit true

[beerandmusic]

51 minutes ago, barrows said:

Wait a minute Alex?  Really, I mean there's the typical country pop stuff, and then there is country, like Patsy Cline, some of Shelby Lynne's stuff, and that of her sister, Johnny Cash might be considered country, right?  I know there might be a it of a distinction between what we might call "Americana" these days, but a lot of it is really country, and then there is the cross over with bluegrass folks like Allison Krauss, etc...

 

i don't like much country, but there are probably 100 or so exceptions....

 

 

[beerandmusic]

10 hours ago, Superdad said:

 

 

On 6/12/2020 at 3:19 PM, OAudio said:

 

 

may be of interest::::

 

https://news.ycombinator.com/item?id=7065091

[beerandmusic]

6 hours ago, OAudio said:

Thanks its a very interesting read,

 

 

Timing,

Signal integrity (inc transmission, detection and cable effects),

PSU influence,

Onward processing, and

USB transfer & error handling,

 

all hotly debated :-).

 

I think the excellent white papers @Superdadlinked above pull these into a broad and cohesive picture.

 

OAudio

 

I never saw your response to superdad about your profession and am curious myself?

[beerandmusic]

3 hours ago, barrows said:

  There are certainly well engineered DACs available which pay attention to all of these details.

 

What is lowest price DAC that you are aware of that does "pay attention to all of these details"?

[beerandmusic]

1 hour ago, barrows said:

 i have no idea, I have not examined all DACs on the market!  Typically, it is more expensive to incorporate good isolation, i have not seen such in low price DACs (like Topping, etc).

You have ask manufacturers about this yourself if your shipping for DACs if they do not specify how their USB input is implemented.

you stated there are many dacs that do this...i wasn't asking which are inexpensive...i just asked of the dacs that you are aware of, which is the least expensive one that you are familiar with?

I believe the schiit dacs do this with their "unison" usb, but Miska said the bifrost didn't measure well, so am looking at other options, and would prefer DSD if possible, but not necessary.

Even of the "many" you suggest, none are inexpensive, I still want to know which is the least expensive one you are familiar with as a "starting point"

[beerandmusic]

1 hour ago, OAudio said:

 

 This has meant a lot of work in the audio server to ensure good USB timing and power (clocks and PSUs are to my own designs). The work has helped promote a well timed USB stream and good USB SI from the server.

 

I don't know if I understood another person correctly or not, but I thought I understood them to say that almost all DACs use their own clock in modern day dacs, so why would the pc source clocks matter regarding timing?

[beerandmusic]

2 hours ago, barrows said:

The current version of the Holo Audio Spring I guess counts as a relatively inexpensive DAC, with a good, isolated, USB interface.

 

Thanks for sharing..this is the type of information i am looking for.

 

In your statement:: Such isolation requires that the DAC re-clock the I2S lines before conversion, hopefully via a masterclock and flip flop located very close to the final conversion stage.  Of course an isolated USB receiver needs a dedicated power supply, this can be provided very well by the USB 5 VDC supply, if one is sure their USB source has a clean/low impedance 5 VDC supply, and that the USB cable keeps this supply clean/low impedance.  

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

Can you clarify. 

1.  Does the Holo re-clock in the manner which you suggest above?

2. Does the holo provide it's own 5v or does it use the usb 5v? 

 

[beerandmusic]

3 hours ago, Superdad said:

Understanding this stuff is hard enough for those non-engineers (like myself) who are steeped in it (I consider myself lucky to be very "engineer-adjacent" via my close relation with John Swenson). I think it is going to be difficult for you to choose based on informal discussion of many technical factors. 

 

That may be true, but how is it possible for anyone to make a decision then on which ones to try?

They can't base it solely on measurements, and they can't base it on debatable technologies.

THat is the problem with the hobby.  Sure you can say base it on your own hearing...I have already tried that as well trying a multitude of them.  No one can seem to offer "logical" reasoning for the layman.  By definition of function of the dac, all dacs should sound exactly the same, and I have yet to find one usb dac that sounds as good as other interfaces.  I am very close to giving up on the endeavor again to find a usb dac that sounds any better than playing from a smart phone or streaming through a cheap avr...  Even the objectivists on the "other site" suggest that all dacs with good measurements will sound the same...so that I guess is where this will end...i guess I just had higher hopes.  I know davide256 suggest the mojo is the answer, where one person over there (that is presumably well respected there), has the mojo and suggests it sounds exactly the same as any other dac that isn't "trash".  Then when you question people (whether they believe all dacs sound the same or you have to have the best pc, the best power supply, the best isolation, and even then it won't be good enough), they belittle you and just say "just believe us", even though they are on totally different belief systems.    One side suggests spend whatever you want they will all sound the same, and the other side suggests you have to spend a fortune, and there are so many improvements....I personally believe that it has to be somewhere in between the two extremes, so I have to use something to guide me....sure i can just buy another 15 dacs and resell them again, and let my own ears decide....and i will probably still be of the same mindset after all that effort, that all these improvements haven't really amounted to anything and that streaming DSD through my marantz still sounds better....and that's not necessarily a bad thing...it actually sounds pretty damn good....i just would prefer to have it sound this good through usb....yawn.

[beerandmusic]

4 hours ago, Superdad said:

 

Anyway, i liked your first response better, that i believe, if i understand correctly, is that all dacs "regenerate" (term used loosely) to indicate it goes through some processor, and no dac literally isolates the usb 5v reference....so we are back at square one...do dacs compensate for usb noise sufficiently or not....one side will say they do and that usb noise cannot make a difference and they will all sound the same, and the other side will say you have to spend a lot of money and they still will not compensate enough.......which is why i would like a dac that does isolate as best as possible since it is "debatable" that audio engineers cannot agree on.

 

That said, i guess, I can simplify my desires in my next usb dac to just be galvanically isolated that measures well and I can skip the part about having it's own 5v reference voltage or one that reclocks....not sure there would be anything else to look for in making a decision.

[beerandmusic]

2 hours ago, mocenigo said:

 

I can perhaps provide an example (not exactly "cheap" of course)

 

The Soekris DAC1541 User Manual states "The dac1541 R-2R DAC circuit is fully isolated from the noisy computer USB interface and the SPDIF inputs are also all transformer isolated" (the also implying that the isolation of the USB init is also via transformer) and in fact on the board there are three little SMD PCB DA101MC transformers.

 

I think any new dac i buy will specifically market galvanic isolation, and if that isn't really necessary, then the topping d90 is looking better all the time...but i still don't think it will sound any better than just streaming with my marantz, as that has been my experience after trying about 15 different dacs.