Tír Na HiFi

Peter Stockwell wrote:

Peter Stockwell wrote: My question wasn't specific enough, I'd seen those two, and was considedering them, but in the end I'm trying this as a reference :

http://www.lindy.co.uk/cables-adapters- ... able-p6859

and I'm going to see if this A&B systems cable, with separate runs for data and DC, is better :

http://www.ebay.com/itm/A-B-SYSTEMS-Ter ... 3a83df5b7c

I didn't try pfm, because of the foo fighters. Thought I'd get a civilised answer here.

Rats, I think it is better! Now, how can that be possible ?

yes

cable sounds different usb, interconnects and speaker cable have similar effect too

if you tried 5 or 6 different usb cables its quite likely you'll find some of them sound different
copper vs solid silver is one of the blatantly obvious ones

Nige I cut the screen at the receiver end on my usb cable, thought it made a difference, also makes it comply with the usb spec.

sbgk wrote:Nige I cut the screen at the receiver end on my usb cable, thought it made a difference, also makes it comply with the usb spec.

Not sure i know what you mean is it this


i think all cables should be shielded and brought to an earth or drain point

its probably emi/rfi at work here

theres so many factors to tackle:(

Nige,
I think what SBGK means is that he disconnected the braid shield at one end of the cable so the braid is no longer continuous from one end of the cable to the other.
I don't pretend to know all the ramifications but I believe this is an overlooked area. Depending on how the braid shield is connected at the DAC end of the USB cable, it can actually bring noise into the DAC through this very connection & set up ground loops.

The USB spec is not too specific in this, I think but anyway I think we have to look at any implications for audio & ground loops & noise ingress would be the ones of concern that are affected by the braid screen connection.

It shouldn't make any difference with my DAC as I have addressed this internally but try disconnecting the braid & using the USB cable on another USB DAC or audio device.

Peter, yes you will probably hear a difference between USB cable if they are of sufficiently different designs. Separating out the 5V carrying wire form the signal carrying wires is an obvious first step to improving USB signalling. It probably introduces noise of various types on the USB signal wires.

Don't mind the PFM foo-fighters - they are so entrenched in their own myths that they can't see how what might be fine for digital communication isn't necessarily fine for digital AUDIO. They ignore the analogue step & claim that anything which has an effect at this step proves that the device is badly designed. What most other people are trying to do is find out what factors DO affect the final analogue output. And the open-minded ones don't limit this search to a single domain because of some misunderstanding about the mathematical perfection of digital - so the search continues into these factors whether in the "sacrosanct" digital domain or in the analogue domain.

John

Ok didn't notice that before that the rear ports are an actual ground (that ground the whole usb cable plugs and shielding if any) that will aid transport of the noise to and from the dac :(

i had hoped/thought it was isolated and that i could bring it to earth

will the like of copper shielding work if not connected to the plugs (isolated)?

shielding usb cable seemed to have good effect here

Just have the shield connected to ground at the PC end.
With the Ciunas, I don't have the shield connected to ground so a fully shielded cable should be fine but in some USB audio devices the shield is connected to ground usually through a cap & parallel resistor.

Yes, I believe that a shield connected to ground at one end (PC end) still shields the USB signal wires