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Re: Audiophile 192 Characterization

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  • Duane - N9DG
    ... ... While I can t explain the behavior I can confirm the results of these tests. Just this last week I ran the PowerSDR program with the 192 setup
    Message 1 of 1 , Sep 26, 2006
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      --- "Marco" ik1odo@... Wrote:

      <snip>

      > The A-192 declares a flat frequency response up to 80kHz
      > while
      > sampling at 192kHz, 24 bits.
      > The measured response is flat up to over 90dB. The
      > antialiasing
      > filter starts cutting here, so not to see aliasing signals
      > in band I suggest that it is useable up to 86kHz.
      >
      > Unfortunately, the noise floor is not flat. From 0 to 3kHz
      > it
      > decreases approx like 1/f, then it's flat up to 25kHz. From
      > there up
      > it increases by approx 5dB per 10kHz, rising by 30dB at
      > 85kHz. I have
      > no idea of the reason for this noise increment; the two
      > channels are
      > different, the R being approx 3dB less noisy than L. Anyone
      > may explain this noise behaviour?

      While I can't explain the behavior I can confirm the results
      of these tests. Just this last week I ran the PowerSDR
      program with the 192 setup for 192 kHz sampling. I was using
      the SDR-1000 for the signal source. I too noted the very
      steep rise in noise as it goes higher in frequency. I didn't
      precisely measure the rise in noise as Marco has done but do
      recall seeing the ~30dB differential in noise floor from the
      high end of the frequency range vs. the the lower
      frequencies. So the claimed 80 kHz upper frequency limit of
      the Audiophile 192 is not really usable from what I can tell.
      This is really too bad because I do like the card otherwise.

      Duane
      N9DG



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