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6347Re: [softrock40] Re: Big signal at 0 Hz even with SR40 is off

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  • Cecil Bayona
    Oct 1, 2006
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      Alberto I2PHD wrote:
      > Marco IK1ODO wrote:
      >> There would be also a peak at 0Hz due to DC
      >> imbalance of the ADC inputs, but the ADCs used in
      >> 24bit souncards have an internal high pass filter
      >> cutting under 1 or 2Hz, suppressing that.
      > Marco is quite right, as demonstrated by these two screen captures. The
      > first is the digitizing process carried on by Adobe Audition, using the
      > onboard AC'97 chipset, with the card input left open. As you can easily
      > see, there is a substantial DC offset produced by the ADC.
      > The same chipset produced this strong zero frequency peak, entirely
      > caused by the DC offset :
      > 73 Alberto I2PHD
      The picture of the single stand alone spike is what one of PC's has, the
      other four have the typical spike with noise going out quite a ways
      slowly and meeting the noise floor about 2-3 KHz away.

      On most PC's that is a rare item most people don't have that kind of


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