USB audio transmission isn’t bit true

[barrows]

1 bit error every few hours or so, and there are likely much less than that, especially with good USB sources, are not going to have any effect on sound quality at all.  This is certainly a non issue for sound quality, especially with dedicated USB sources.

 

I have both direct ethernet input DACs and USB input DACs being fed from Ethernet Renderers with USB output.  The latter produces the best sound quality.  When done well, there is nothing wrong with USB audio, as with any interface, analog or digital, it does need to be done well if the best sound quality is desired.

[barrows]

There is nothing fundamentally "wrong" with USB audio, period.  Bit errors do not cause subtle degradation in sound quality, period.  With a good USB source and a good USB receiver, very high levels of audio (DSD 512 for example) can be transmitted without any significant errors.  Perhaps, maybe there might be a single error every once in awhile (as in once every few hours): there is no way that such causes any sound quality degradation.

Just like any transport medium, the quality of the source device and the quality of the receiver device matters.

Same is true for Ethernet.

 

There is no inherent problem with USB audio period.

[barrows]

58 minutes ago, Superdad said:

 

There ought to be, but then again I don't know a lot of audiophiles who listen to much country music. 

[Where are you Garth?!]

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...

[barrows]

As an addition to this discussion, I would add what I think the Lush USB cable "does" to make it sound different.  PeterSt. has kind of hinted at this, but has never directly admitted it to my knowledge.  PeterSt does admit that the Lush USB does not conform to the USB impedance specifications, purposefully.  He seems to claim the cable is slower: ie what we would call poor signal integrity, with more slope in its rise and fall.  What he appears to be saying that this does is that the slower transition edges hit the receiver more "softly", and then he suggests (again, I am reading a bit between the lines of what he says, PeterSt is often a bit obtuse, perhaps on purpose to not give away his "secrets") that this softer hit, gives rise to less RF/noise generation in the receiver.  I am not aware if anyone has ever actually measured this, it should be measurable by an RF lab at the very least.

 

I can say that the Lush (my experience was with the original version) does exhibit a "softer" "warmer" , even a bit "fuzzy" presentation from a subjective perspective (it was not for me in my system).

I would say that how the USB "system" interacts is going to matter, as is true for most signal transmission "systems"

 

For me, given a good USB source (dedicated, not a commercial computer which is multi tasking while playing music, and no shared devices on the USB bus) and good USB receiver in the DAC, I am certain that data errors are not an issue for sound quality.

 

For me, that leaves only the various forms of noise.  Including noise generated by the receiving device.  The noise on the receiving chip may change with signal integrity, and power supply impedance/noise.

 

I have always found good isolation of the USB receiver section in a DAC to help matters, but we must understand that such isolation s not a panacea: it helps, but cannot fix all issues.  This is likely because some noise can capacitively couple across a 4 mm "moat" on a PCB.  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.  For the USB power supply in the source, as an example, Sonore opticalRendu pays specific attention to the quality of the USB 5 VDC supply, with a dedicated LT 3045 regulator a few mms from the USB output.  One can also use devices like the IsoRegen to inject a clean 5 VDC supply.  Good layout inside the DAC in terms of airborne RF interference from the USB receiver is a good idea as well and perhaps some shielding/damping as well.   There are certainly well engineered DACs available which pay attention to all of these details.

[barrows]

3 hours ago, beerandmusic said:

 

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

 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.

[barrows]

34 minutes ago, beerandmusic said:

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"

The current version of the Holo Audio Spring I guess counts as a relatively inexpensive DAC, with a good, isolated, USB interface.  Like i said, i am not aware or every dAC available, and the technical details of all.  So to be fair to DAC manufacturers I really do not want to make a list.

Anyway, if you are shopping for DACs, perhaps you could do some of your own research on this instead just asking for other's to do it for you.  Ultimately, to decide on any DAC purchase, a listening test at home in your system is the only way to go, as not everyone is gong to agree on which s "best' and different system contexts matter as well.

[barrows]

10 hours ago, beerandmusic said:

I have yet to find one usb dac that sounds as good as other interfaces

The above suggests to me that your USB source is the problem, not the DACs you have tried.  If you are just plugging in a commercial computer to evaluate the DACs, that is a mistake:  The USB source matters, there is a reason that custom servers with dedicated USB output cards exist; there is a reason that Ethernet Renderers with carefully designed USB outputs exist.

 

Even something as simple and affordable as the Sonore microRendu has a much, much better USB output than any commercial computer.

 

Add Chord Qutest to your list of affordable DACs with an isolated USB input receiver.

 

BTW, measurements have shown for quite some time that the USB input on many DACs is at worst equal to the SPDIF input, and the USB input on many DACs often measures better than the SPDIF input-check out the jitter measurements of the different inputs done by John Atkinson over at stereophile.com.  Note that those measurements were mostly done with a MacBook Pro directly connected to the DAC, and even still, the USB input often performs better than the SPDIF inout.