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mansr

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  1. Here's a quick analysis. To start with, look at the spectrum of the DXD source: Just above 22.05 kHz there is a very small amount of analogue noise. This is followed by a fairly flat noise floor up to 44.1 kHz. Beyond this, we have increasingly strong modulator noise from the ADC, reaching -100 dB/Hz at top end. It is safe to say that this music would have been captured perfectly at 88.2 kHz. Dropping the sample rate to 44.1 kHz loses nothing of value. Now add the spectrum of the 16/44.1 source file along with 16-bit TPDF dither for reference: The curves are clearly diverging above the centre, the 16/44.1 version being higher in level. Plotting the power ratio shows this more clearly: Moving on to the captures, their spectra show the same diverging trend, albeit to a smaller extent: And the power ratio of the two captures: Finally, the power ratio of (what I assume is) the DXD capture to the source: The bulk of the music content is about 0.2 dB lower in the capture, while at high frequencies the noise is much stronger. The only anomalous thing here is the discrepancy between the DXD original and the 16/44.1 version. A plain downsample shouldn't differ that much. I wonder if perhaps they intentionally boosted the highs by a few dB for some reason. As for the captures, the ADC has possibly been a limiting factor here. I would have used a 24-bit ADC at a higher sample rate to make certain nothing was missed.
  2. Just FYI, your sarcasm detector appears to be broken.
  3. mansr

    Some commonsense

    I understand you want to compare something between a DSD256 file and a downsampled version of it. You also mentioned spectrograms. Starting with a DSD256 file from a NativeDSD sampler (track 5 from this album) I happened to have handy, here's what I've done: Downsample to 44.1 kHz. Upsample to DSD256 rate, keeping 24-bit sample precision. Subtract the original DSD samples (as ±1 values). Plot spectrogram of difference up to 44.1 kHz. Above 21 kHz, we see a little high-frequency content from the recording that was lost in the 44.1 kHz conversion. Below that, nothing. The level of the difference in the 0-20 kHz range is -170 dB RMS, -155 dB peak. This is too small to be representable in 24-bit precision. Is this anything like what you were looking for?
  4. mansr

    Some commonsense

    Well, there's https://www.native-instruments.com/en/specials/stems/. Only four tracks though, and releases are limited to club/dance music.
  5. mansr

    Some commonsense

    You have yet to specify "the exercise."
  6. mansr

    Some commonsense

    I mean typical as in the bloody dictionary definition of the word.
  7. mansr

    Some commonsense

    Well, obviously any frequencies higher than half the new sample rate are lost. This should not be news to you. Besides that, imperfections in the decimation filters will have a few minor effects: Very slight passband ripple. Some drop-off a little before fs/2. Aliasing of residual high-frequency content due to finite stopband attenuation. The details can be found in the ADC data sheet.
  8. mansr

    Some commonsense

    I have never listened to a Lady Gaga track. I understood Jud's "typical" to mean representative of music production in general, not whatever any one individual chooses to listen to.
  9. mansr

    Some commonsense

    The modulator is whatever the chip designers at TI, AKM, or wherever concocted. I'm still struggling to understand what exactly you're looking to achieve. We already know that the noise level in a 24-bit recording is determined by microphone preamp, not the ADC. What does it matter if a couple of the lowest bits are altered by the decimation filter?
  10. I just got a UPS delivery, so I asked the driver about their trucks. He said the fleet is currently being converted from diesel to hybrid electric. This is the local delivery trucks, not the long-distance haulers. He didn't mention those.
  11. Someone should bring a remote control jammer to one of those demos.
  12. mansr

    Some commonsense

    Most ADCs use a multi-bit sigma-delta A/D converter. The data it produces is then digitally processed on-chip to produce PCM or DSD output. The 1-bit modulator providing the DSD output may well cause at least as much "damage" as the decimation filters used for PCM.
  13. mansr

    Some commonsense

    It's not about what I or you want. Jud specifically said he was interested in "typical" recordings. In a typical music release, the final master is not intended to sound the same as the microphone feed. That's just how it is, like it or not.
  14. mansr

    Some commonsense

    Right. Assuming you can indeed hear a difference, this is as likely as any.
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