2. digital
  3. 159217-149317

USB sucks

USB really isn‘t the right connection between DAC and Server: depending on cables used, you get very different sound quality if the server manages to recognise the DAC at all. Some time ago I replaced my highly tuned Mac Mini (by now-defunct Mach2mini, running Puremusic via USB) with an Innuos Zenith Mk3. For starters I couldn‘t get the DAC (Antelope Zodiac Gold) and server to recognise each other, transmission from the server under USB2.0 wasn‘t possible because the server is Linux based (mind, both alledgedly support the USB2.0 standard) and when I finally got them to talk to each other (by using Artisansilvercables (pure silver) the sound quality was ho-hum. While I understand the conceptual attraction to have the master clock near the converter under asynchronous USB, the connection‘s vagaries (need for exact 90 Ohms impedance, proneness to IFR interference, need to properly shield the 5v power line, short cable runs) makes one wonder, why one wouldn‘t do better to update I2S or S/PDIF or at the higher end use AES/EBU. After more than 20 years of digital playback, the wide variety of outcomes from minor changes seems unacceptable.

Since then and after a lot of playing around I have replaced the silver cables by Uptone USPCB rigid connectors, inserted an Intona Isolator 2.0 and Schiit EITR converting USB to S/PDIF. Connection to the DAC is via Acoustic Revive DSIX powered by a Kingrex LPS.

The amount of back and forth to make all this work is mindboggling, depending on choice of USB cables (with and without separate 5V connection, short, thick and God-knows what else) is hard to believe for something called a standard interface and the differences in sound quality make any review of USB products arbitrary verging on meaningless.

Obviously S/PDIF gives you no native PCM or DSD but, hey, most recordings still are redbook, anyway.
Conversely it is plug and play although quality of the cable still matters but finally it got me the sound quality I was looking for. It may not be the future but nor should USB, given all the shortcomings. Why is the industry promoting a standard that clearly isn‘t fit for purpose?

Finally, I invite the Bits-are-bits naysayers to go on a similar journey, it just might prove to be educational.
antigrunge2
herman
2,259 posts
 


Most USB audio/video devices use the bulk transport because real-time delivery of the data is not necessary.
This simply is not true if "most" includes the topic at hand... USB DACs? 

 As a programmer and electronic interface design engineer, you're not "locked" into using isochronous mode: You have bandwidth and buffers so if i can transfer 500 MBps+ (using SATA SSD = 4 Gbps+) of data without error (well, if there are errors, they are corrected), it should't be a problem to playback music!

It doesn't matter what could be done. It matters what is done, and since asynchronous is what is done, errors are not corrected. End of story.
herman
2,259 posts
 
@antigrunge2 

Since you like the Antelope DAC: may I suggest you try it on S/PDIF or AES/EBU?

fair enough, but how do you generate the signals? There are a few ways I know of, Ethernet to spdif with a

  • Raspberry Pi HifiBerry seems like a step back, maybe not
  •  DCS network bridge, $3500 , more than I paid for the Antelope
  • $20K+ Aurender W20, not an option for me

Of course there are USB to spdif but we are trying to eliminate USB. 

suggestions ??

redlenses03
94 posts
 
Far from having ‘dissolved itself‘ I sincerely hope that this thread might lead serious designers to reconsider whether rather than using a low end, convenience consumer interface with all its known foibles to transmit high quality audio, one might usefully revisit more appropriate formats (optical, I2S, AES/EBU) to improve on what is at best an unacceptably wide range of outcomes with USB; I also note with a degree of puzzlement that members of the ‘bits are bits’ school of sitting on your ears are alive and well

Respectfully, it kinda has.  Its' just another "I'm right you're wrong" (not directed at you).  Armchair experts everywhere.

Its fine to not like USB, or.......but keep in mind it's an individual use case.  This thread isn't going to change a designers mind to all of a sudden say, "hmm someone on the web doesn't like USB, I should probably use spdif"
The amount of info with issues, aka " with all its known foibles" on every interface is easily documented / found.  i2s, AES etc.. ALL have (potential) issues/shortcomings, given how its implemented in certain products.  It's either done right or not.  Again, implementation has been repeated ad nauseam.  That's the bottom line on how I see it.

I'm not trying to change anyone's mind, why would I care, whatever floats your boat.   Everyone's use case (which is pretty critical in the overall scheme of things) is different and It's really about having a mature discussion. 


audioman58's avatar
audioman58
4,168 posts
 
I beg to differ Schiit Audio New unison usb is even better then Bnc,or Spidif 
I compared several cables in the $500 range and even less the  Unison USB
card was clearly more resolved and natural sounding .this new card does take around 200 hours to fully runin .
but is an advancement over Xmos 
or others multi function processing models .this being proprietary and only does 1 function ,and does it well. 
dutchydog
56 posts
 
I just dropped my cartridge needle down onto my vinyl record or put my CD into my CD player and hit play and I get great music and nothing to worry about
More to discover