Why do different USB ports sound different?

[Count Arthur]

My twopence.

Anecdotally, on a previous PC, I had an issue with the DAC connected to the PC where I would hear noise, a sort of high pitched whine, when I moved the mouse. Connecting the DAC to a different port on a USB PCIE expansion board fixed the issue.

The USB ports on the outside of a PC case are not all connected and implemented the same way within the PC. Ports on the front of the case will be connected via a header cable, whereas those on the back plate, are connected directly to the motherboard - a possible source of noise?

On the motherboard itself, different ports are connected in different ways to the CPU, some directly, some via the chipset.

Exactly how this is implemented, varies with different CPU and chipset brands and models:

All this is to say, that not all the USB ports in a PC are completely identical. What the specific issue is, I couldn't say, but given that some ports are connected/implemented in a different way suggest that there is a mechanism for there to be issues with some ports and not others.

 

[somebodyelse]

Unless galvanic isolation becomes the standard (as Eversolo does with its new streamer) this will be an ongoing issue,no matter how nicely a DAC measures in isolation or how well is made.

Or people switch to properly implemented balanced interconnects so that ground noise doesn't get mixed into the audio signal.

 

[somebodyelse]

All this is to say, that not all the USB ports in a PC are completely identical. What the specific issue is, I couldn't say, but given that some ports are connected/implemented in a different way suggest that there is a mechanism for there to be issues with some ports and not others.

Ground routing, and what else shares the same ground route as your USB port. If it's something with variable current consumption that variation will modulate the ground voltage at your USB port.

 

[Sokel]

Or people switch to properly implemented balanced interconnects so that ground noise doesn't get mixed into the audio signal.

We have seen the issue with balanced connections too (more rare though),usually to active/powered speakers.
There,we have a whole different mix of classes and ground points as these speakers are often connected to different ground points (obviously if they are 3 meters apart)

 

[EJ3]

Yep, will happen but does not change the sound. It could only add some unwanted noise(s) in a poor performing DAC.
As can be seen the mains leakage adds 60Hz (+ harmonics) at inaudible low levels to the signal in the AB cable but nothing changes to the sound signature.
It is also very clear that the harmonic distortion (nor will FR) change in the slightest way.
The 'added noise' in the wireworld cable is also an 'added' signal (at inaudible levels) but adds no significant mains leakage.

How this pans out on any other DAC in a totally different situation using different gear cannot be shown in these graphs so it cannot serve as evidence.
In any case ... neither cable changes the sound quality nor 'tone' and it simply can't.

The only thing that might happen is added 'unwanted' crap that will not be related to music.

And to those who don't have the technical way of describing things that we do: to them: It simply means that it sounds "different".

 

[LongKick64]

Ordered Topping HS02.

 

[Crosstalk]

People are free to do a lot of counter-productive things, which are not worth doing.

Probably are worth for them.

 

[Saponetto]

Final freedom is via optical, I'd finally see the light.