USB Cable with No Power


I have an externally powered QuteHD DAC and so I was thinking why would I need the power from my pc to the DAC?

Would it be a good thing to get a USB cable with the power leg disabled?

Is this even possible and would it still be USB 2 capable?
photonman
Elijah audio make one that's really nice. They also make one that has a separate battery supply for the USB 5v
If the receiving device does not use the power then it will not be sucking power via the cable.
Just like your household outlets are wired to provide power.. if they are not in use then they just do not have power flowing through them.
So no need for a special cable.
hmmm...okay, that makes sense. Thanks.

Gosh, talk about over thinking things.
[shaking my head at myself]
To follow Elisabeth.

You have a few options if you MUST go this way.

First you must understand that desire not to use PC power is the desire not to carry ground noise to your DAC, so:

1 Use dedicated server where this problem (and, hopefully, many others) is solved

2 Use USB Cable with interface like iFi where you can use iFi power (it will work even better if no power will come from PC to your USB port). Its also not cheap as you need to buy iFi as well as two quality USB Cable (to and from iFI). iFi supplies terrible quality USB cable which, IMO, negate advantages of iFi

3 Use USB Cable where noise is "grounded" .

From my past experimentations with our Musica Pristina servers the last solution is the best.

All The Best

Simon
Musica Pristina
Simon,

Who makes such a cable?
"Who makes such a cable? "

- Entreq. They developed USB cable(s) for $100k dCS and we work with them.

Simon
Musica Pristina
"First you must understand that desire not to use PC power is the desire not to carry ground noise to your DAC"

Not true. Even the USB cable with no power wire in it still needs a ground wire in it or it will not work.

Revelation makes an unpowered cable. You can purchase it on:
http://www.empiricalaudio.com/products/off-ramp-converter

The only way to reduce ground-noise with this type of cable is a common-mode filter, like this:
http://www.empiricalaudio.com/products/short-block

Steve N.
Empirical Audio
"Even the USB cable with no power wire in it still needs a ground wire in it or it will not work "

Exactly. This why Entreq USB cables I recommend have a ground wire(Eartha) as well as the grounding box (Maxumus).

Simon
Musica Pristina
lol @ Photoman's comment,"Gosh, talk about over thinking things."

I do like honest, keeps it real in here...heheh