Kij - Async USB is quite immune to jitter from the USB signals, however it is not immune to jitter caused from noise on the ground or the power wires in the cable.
This is why USB cable common-mode filters like the Short-Block are so effective:
http://www.empiricalaudio.com/products/short-block
I also now have a USB filter and power supply combo called the Power-Block. If your USB interface needs the 5V power, such as the Berkeley converter and others that have galvanic isolation, the Power Block can make a big difference in SQ:
http://www.audiocircle.com/index.php?topic=128620.0
The cable is still important in either the case of the cable-powered or device-powered USB interface.
Steve N.
Empirical Audio |
As I understand it, asynchronous USB uses internal DAC's clock
for the D/A converter. This clock is independent
(asynchronous) to USB data rate. For that reason data has to
be buffered. DAC has to request different number of samples
each frame to keep data buffer between underflow and overflow.
Since D/A converter uses data from the buffer (memory) with
internal clock, then quality of the cable lies only in good
shielding to prevent electrical noise contamination of the
DAC. In synchronous USB D/A converter clock comes from the
computer. Usually D/A converter runs from internal clock that
is synchronized with incoming USB clock by PLL (Phase Lock
Loop) but it is less than perfect. This scheme is used in
pretty much every CDP, except here incoming USB clock can be
very jittery. |
Dtc,
I have learned a lesson here and thanks for your last thread, which make me feel better now. |
Sorry I was a bit harsh. I am constantly surprised how many people never try to bring their treads to closure. You at least did, although in a different thread. I found the discussion helpful, so thank you for that. Good luck with the never ending hunt for better cables. |
Dtc,
If you follow my thread, I have asked a question to the Audiogon community and besides Cerrot's comment, I did not get a clear answer to my question. So I decided to get the answer by myself by purchasing the Furutech cable and do the evaluation all by myself!
So in the interrest of the Gon community, I have created a new thread with a punchy title. However I must concede that you score a point about following up on the topic and I apoligize for the frustration generated. |
Hate to say, but a completely different thread in a different forum is not very good follow-up. I would never have linked the two topics. A comment with a link would have been nice. People gave you advise and never heard back and probably never found the other thread. Sorry, but that just happens too often in this forum. Sorry to be a bit ornery, but I would like to see OPs seek closure on threads. Too ofter it does not happen. Not just you. Dismount soapbox. |
Dtc and Mceljo,
Please view my follow-up thread titled 'USB printer cable VS USB audiophile grade cable?'. Yes, there was a clear positive difference.
Mceljo, I did get intermittent sibilance/background noise while using the printer cable, which I did not understand where it was coming from. I initially tougth that it was coming from noise on the AC line or intermittent problem with my DAC, but none of this occuring while using the Furutech cable.
However, it could be a little too soon to conclude definitively on this, since I only had the Furutech for 5 days. |
If you could not tell a difference between optical and USB then I would suggest that EMI / RFI may not be a significant factor as the optical connection is immune to it. Is it expected that the USB connection be superior so EMI / RFI would be the reason it wasn't superior? |
So, do you hear a difference? |
Mceljo,
I was referring to potential EMI/RFI interference on the 12ft. USB cable. The printer USB cable construction quality is far behind the Furutech cable design. |
What is the connection between EMI / RFI and the digital signal in the USB cable? You have already said that you couldn't hear a difference between Toslink and your printer USB cable. Can we all agree that EMI / RFI have no effect on the optical Toslink connection. |
I bet you a dollar you will hear a very nice improvement. |
I just ordered the Furutech GT2 Pro USB cable from PartsConnexion and should get it next week. I will keep you posted on my listening sessions.
My gut feeling is that there will be no changes in audio quality, but will have a better quality build than my printer cable. The Furutech should be immune to RFI and EMI which is all good to me. If I get better sound, it will be a bonus :-) |
Doggiehowser,
Thanks for your reply. Agreed that room acoustics is an oversigth by many audiophiles but already have this covered.
Coming back to the USB cable issue, I'm not worried that much by jitter, but stuff like EMI, quality of mechanical contact, cable impedance mismatch/reflections between PC and DAC,etc. Being curious about this subject, I may bite the bullet and purchase the Furutech USB cable. Worse comes to worse, I may not hear any difference but will be secured by the fact that Furutech builds top notch cables/connectors. |
There was this aspect of testing that always bugged me.
I have tested components and cables in most dealers' setups where there were always noticeable improvements/changes when we swapped some things out.
But at home, the differences were always much more subtle.
Recently I have been helping a friend set up a demo room for his speakers and I think I might have figured out why this was the case. Room acoustics.
My rooms had none/little. I had carpets/shelves and furniture in the room which reduced the amount of echoing but I have never treated the room with foam etc.
In my friend's shop, my friend used some simple foam/bass traps on the side walls, front/rear walls and ceilings. And suddenly, the changes we made became very noticeable.
All this is a very longwinded way of answering your question - would the Furutech cable make a difference? It depends.
Take the room out of the equation and what I've noticed it is that changes upstream in your system becomes much more noticeable. |
