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Re: V9 output to audio card?

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  • R. R. Robson
    ... call the ... small value ... through ... there. If it ... cable then ... disconnected to ... gives the ... that to ... until they ... Ah, the brits and the
    Message 1 of 10 , Jan 2, 2009
      --- In softrock40@yahoogroups.com, "Alan" <g4zfq@...> wrote:
      >
      >
      > ----- Original Message -----
      > From: "Ken" >
      > > By "mains frequecy" you mean the 60 (or 50) cycles of the power line?
      >
      > Yes, I thought I was talking the wrong language! Over here we often
      call the
      > 50Hz main power supply line "the mains"
      >
      > > A "lowish" value (such as in the pF range?)
      >
      > That depends on the frequency and the line impedance. 10nF is a
      small value
      > at 50/60Hz so offers a considerably higher impedance than the direct
      > connection via the audio cable. Therefore little LF current flows
      through
      > the capacitor.
      >
      > > while allowing the "spiky" USB signal to pass....
      > > Is there any signals as such on the ground wire of the USB connection?
      >
      > The spiky USB signal has to return to ground, so yes, they are
      there. If it
      > is a good low-resistance ground connection they will not be noticed.
      >
      > > AND does the ground wire not need to be a DC ground that would be
      > > blocked by a capacitor?
      >
      > The DC ground is connected via the audio ground.
      >
      > > are you suggesting putting this "lowish" value capacitor on all the
      > > USB wires to isolate them to prevent any ground loops?
      >
      > If there is a good ground return to the USB by way of the audio
      cable then
      > this capacitor may not be needed. I leave the USB ground
      disconnected to
      > avoid a ground loop at low frequencies. The 10nF capacitor just
      gives the
      > spiky signal an alternative route.
      >
      > Again I stress that this is just the way I have done it. It seems
      that to
      > get the best results it may be necessary for people to experiment
      until they
      > are satisfied, their conclusions may differ from mine .
      >
      > 73 Alan G4ZFQ
      >
      Ah, the brits and the americans - two peoples separated by a common
      language!
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