USB DAC input filter

Nikitas

Member
2011-11-11 9:13 am
I'd like to tinker with the USB input of my dac (PC source),
specifically "clean up" power and ground,something like the jitterbug/iUSB/wyrd.

Has anybody done anything similar? any advice where to start?
Filter types, values, what to be careful with or tips?

Cheers!
 

Nikitas

Member
2011-11-11 9:13 am
Is it possible to completely cut off 5v and ground?
And leave connected only D+ and D-? Would that work?
D+ and D- are a differential signal or two independent signals?

i can't find any detailed info about what's going on inside that USB connector
from wurth....
 

wwenze

Member
2008-03-07 12:46 pm
Is it possible to completely cut off 5v and ground?
And leave connected only D+ and D-? Would that work?
D+ and D- are a differential signal or two independent signals?

i can't find any detailed info about what's going on inside that USB connector
from wurth....

Both yes and no, you need at least the ground.

D+ D- is differential. However they cannot be left floating, otherwise when the voltage of both D+ and D- rise too far from the load's ground it will not work.

And a lot of noise comes from having the ground connected.

That is where the isolator comes in handy. Or get SPDIF.

The issue with isolators - transformer or electronic or otherwise - is that they tend to have an upper limit on supported signal frequencies, unless you're willing to pay lots.
 
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I use a ferrite & 4 USB cable loops. The solution (see the photo) provides great sound improvement in bass definition, spacial positioning, speed & timing. Amazing really...
 

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The problem with most of the available isolators is they don't actually isolate the computer noise, the Jitterbug being a perfect example. most noise from the computer is high frequency (I would like to see some figures of how much noise is getting down the USB) the Jitterbug is not laid out with any consideration to this noise and the coupling mechanisms of the noise, so its useless as I believe measurement's on the WEB (and from stereophile I believe) have shown.
I second a ferrite it will do as much if not more than some of the dubious offering....
 

Nikitas

Member
2011-11-11 9:13 am
Boky, thank you!

Marce, thanks for joining! I was actually looking forward to your reply
because in another forum I read a reply of yours (I think computer audiophile)
and it was very interesting.
Could you maybe offer your opinion on the below post:
"ok, I'm having trouble understanding something:
I aim for a (third order?) filter for the data lines, common mode type.
What frequency(ies) do I target? should it be high pass or band pass?"
I can't find a source clearly stating which is the bandwidth of data transmitted/received.

Have you tried something like that? Do you think it would offer a better result comparing
to ferrites?