USB SQ, what can one expect

Cerrot - there are too many folks using USB with great results to make your claims credible. Give it up.

Steve N.
Empirical Audio

Cerrot - some might say - you are talking out of your USB port :-)

Perhaps you are correct if you are referring to USB 1.0 ports in both computer and DAC, but with asynchronous USB 2.0 in both - it's a whole different ball game.

Especially if the DAC is designed specifically to handle asynch USB 2.0 data transfers

Is it the best method? - who knows - but it is now so much better than it used to be and if you are that persnickety you'll take another approach.

Once ripped with DBPoweramp - I think anyone will be able to see just how good asynch USB 2.0 can be.

Regards...

Willie, it has gotten better but no where near an spdif implementation.

Cerrot - please don't interprit this post as me being argumentative, since I am all about getting to the bottom of things and the USB vs S/PDIF debate has been ongoing for some time.

I just did some surfing on the web and found this article, which seems to indicate USB is quite capable of quite high resolution playback. It appears to take a little more "scientific" approach, rather than the "personal observations" posted on many forums, which can be "coloured" by many other factors in any given audio system

http://thewelltemperedcomputer.com/Intro/SQ/USB_SPDIF.htm

EXA's post on this forum supports the above

USB to DAC vs. USB to SPDIF then DAC

But then he made this comment...

Asynchronous USB interfaces are not sensitive to the quality of the USB cable.

I have personally experienced better USB cables do make a discernible difference i.e. in my system!

Since I'm no expert in this field it's always useful to get the opinion of others, so if you could take time to read it and provide some feedback, I for one would appreciate it.

If you know of other counter arguments on the web it would be most helpful

I tend NOT to believe everything I read on the web on first read, so feedback from others is crucial in order to arrive at a more informed conclusion.

If anyone else has "scientific proof" one way or the other, your feedback would also be appreciated - by me at least :-)

Many Thanks in advance

Willie wrote:

"Asynchronous USB interfaces are not sensitive to the quality of the USB cable.

I have personally experienced better USB cables do make a discernible difference i.e. in my system!"

It is true that Async eliminates the problem of jitter from the computer getting into the master clock of the Async interface, however there are other mechanisms that can still cause jitter due to the USB computer interface and the USB cable.

The main mechanism is common-mode noise. The USB interface is differential, so in theory all that matters in the signal is the difference between the two signal wires. However, in practice any noise on both signals (common-mode noise) is not rejected completely by the Async receiver. Because this noise is not completely rejected, it adds to jitter in the Async interface.

There are a couple of ways to eliminate or reduce this noise:

1) filter the USB interface
2) use a galvanically isolated USB interface

I have solutions for both of these:
1 Short Block
http://www.empiricalaudio.com/products/short-block

2 Power Block
http://www.audiocircle.com/index.php?topic=128620.0

Another mechanism that can cause USB cables to differ is the error rate. It is best to get a high-quality USB cable. Same for S/PDIF coax. Use a high-quality cable there too.

Steve N.
Empirical Audio