Computer Audio Asylum

Posted by pryamomimo (A) on February 23, 2008 at 19:28:36

In Reply to: RE: USB isolation hub (Gordon, audioengr, John - input wanted) posted by DHT 4 ME on February 23, 2008 at 14:56:46

AFAIK, most of USB chips (at least the ones involved here) need both the differential data pair, AND the power lines for device identification, even if running in self-powered mode.

I think it is Gordon who uses a different TI USB chip at the DAC end that needs just the differential data pair. I guess your suggestion might work in this case.

• RE: Removing power pin - John Swenson 12:12:29 02/25/08 (0)
  In Reply to: RE: Removing power pin posted by pryamomimo on February 23, 2008 at 19:28:36

  Actually even the 2706/7 can run fine without the actual +5 volt wire on the cable in most circumstances.
  
  You HAVE to have the ground wire though. You still need a voltage reference (ie ground) for the differential pair. As I said before putting chokes etc in line with the ground is a bad thing to do as well. Some designs do that to try and meet EMI specs, but all it can do is mess up the quality of the data transmission.
  
  John S.
  
  

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